Strength of soil-lime mixtures

Engineering has been defined as the art of organizing and directing men, and of controlling forces end materials of nature for the benefit of the human race, I*.an has been able to control some forces and has found new materials, like concrete, steel and brick, which he is using for his benefit, but soil is the oldest and probably the noat used of engineering materials, and yet working knowledge of the structural properties of this material Is meager as compared with the knowledge of the newer ones. The word soil carries different meanings with different engineers, according to the use to which it is put. The geologist, concerned with the study of soils as part of the earth as a whole, is interested in the formation of individual soil materials from the parent rock and the methods whereby these materials were mixed and deposited in the layers of the earth's surface. The agronomist, interested in th,i properties of soil influencing plant growth and the methods by which natural soils may be improved from the agricultural 1 standpoint, looks at it from quite a different point of view. The industrial chemist, using it for the manufacture of cement, glass, ceramic materials and other products, studies its onemical properties and defines it accordingly. The civil engineer stadias it as another construction material, bis every structure, whether a building, dam, bridge or a highway, rests on soil, which shows the importance of tnis material to him. Though man's experience with soil has oeen long, the properties tuat concern the civil engineer have been completely crystallized ana put together only during the last twenty-fice or thirty years.

STRENGTH OF SOIL-LIME MIXTURES by Anand Singh Bishnoi A thesis submitted to the faculty of the University of Utah in partial fulfillment of the degree of Master of Science. Approved; Chairiuan^ ihesiu 'Co^sftt^e Bead ^.via .1 or Je/EartnantHT c l.___________________________ ______________________ he'&nV G-r&^ate^Sho^/ ~ University of Utah 1949 ACKNOWLEDGMENTS The author acknowledges with pleasure the help received from and expresses grateful appreciation to: Associate Professor K, L* £loaae, for his con­stant heij, anu guidance throughout the ccurse of this investigation* IJrofessor A, Diefendorf, Head of the Department of Civil Engineering, for hie gener 1 auviee; A: ecciat® Professor G, Littlefield one -r, P, D, Linford for the use of the materials laboratory and the concrete laboratory for conducting tome of the tests. ii TABLE OF CONTENTS Page ACKNOWLEDGMMT ........................... 11 LIST OF TABLES....... .................... iv LIST OF ILLUSTRATIONS.................. v I. INTRODUCTION Soil.......... ................. . 1 Classification ......................... 2 II. STABILIZATION, GENERAL ...*...... . 6 III. LIME IN SOIL STABILIZATION......... ...... 19 IV. HISTORY AND DEVELOPMENT OF SOIL-LIME MIXTURES ....................... 22 Road Construction with Lime ............. 32 Construction Methods for Soil- Lime Road ....... .............. . 37 V. PRESENT INVESTIGATION Problem......... *..................... 39 Tests ........... *..... ............... 41 VI. RESULTS AND DISCUSSION ................. . 50 Conclusions ............................ 70 VII. APPENDIXES Appendix I Classification and Compaction Data ........... 73 Appendix II Experimental Test Data ..... 89 Appendix III American Association of State Highway Officials . Test T 99-38 for Moisture .. Density Relation ..........106 Appendix IV Apparatus for Capillary- Wetting of Specimens..... 112 Appendix V List of References..... . 115 iii Table Page 1 . Hesults of a Test Performed on a very Plastic Gumbo Clay ................ 27 2. Effect of Lime on Plastic Gumbo Clay ..... 27 3. Hesults of Tests on a Medium Clay...... ... 28 4. Effect of Lime on fcedium Clay .............. 28 5. Effect of Lime on a very Plastic Clay .... 32 b. Optimum Moisture and Maximum Dry Density for Haw Soil.......... ........ 51 7. Optimum Moisture and Maximum Dry Density for Soil-Lim3 Mix .............. 51 8 . Unconfined Compressive Strength Test Data for Soil-Lime Mixture...... 54 9. Capillary Moisture Data for Soil-Lime Mixtures ..... ............. 54 10. Moisture Content of Haw Soil Specimens after Capillary Wetting ................ 64 LIST OF TABLES iv LIST 01* ILLUSTRATIONS Figure Page 1 . Colloidal Particle la Free Water ........ 11 2. Samples in Moist Cabinet on Wetting Device 46 3 . Testing Specimens in Compression Machine ....... ......... . 47 4. Samples Failed in Unconfined Com­pression ‘Test .... ................. . 49 5. Compressive Strength of So11-Lime Mixtures .............................. 55 6. Capillary Moisture in So11-Lime Lixtures ....................... ...... 56 7. Capillary Moisture for Sand and Lime 57 8 . Capillary Absorption Curve for Kaw Soil Specimens ........ .............. 65 9. Haw Soil Sample after Capillary Wetting of 28 Days ................... . 67 10. Soil-Llme Mixture Specimens after 28 Days ........ ................ 68 11. Moisture Density Curve for Raw Soil ...... 81 12. Moisture Density Curve for Sand ......... 83 13. Lioisture Density Curve for So 11-Lime Mix . 87 14. Density Cylinder...................... Ill 15. Apparatus for Capillary 'wetting ......... 114 v INTRODUCTION tioil,- Engineering has been defined as the art of organizing and directing men, and of controlling forces end materials of nature for the benefit of the human race, I*.an has been able to control some forces and has found new materials, like concrete, steel and brick, which he is using for his benefit, but soil is the oldest and probably the noat used of engineering materials, and yet working knowledge of the structural properties of this material Is meager as compared with the knowledge of the newer ones. The word soil carries different meanings with different engineers, according to the use to which it is put. The geologist, concerned with the study of soils as part of the earth as a whole, is interested in the formation of individual soil materials from the parent rock and the methods whereby these materials were mixed and deposited in the layers of the earth's surface. The agronomist, interested in th,i properties of soil influencing plant growth and the methods by which natural soils may be improved from the agricultural 1 standpoint, looks at it from quite a different point of view. The industrial chemist, using it for the manu­facture of cement, glass, ceramic materials and other products, studies its onemical properties and defines it accordingly. The civil engineer stadias it as another con­struction material, bis every structure, whether a build­ing, dam, bridge or a highway, rests on soil, which shows the importance of tnis material to him. Though man's experience with soil has oeen long, the properties tuat concern the civil engineer have been completely crystallized ana put together only during the last twenty-fice or thirty years. Jlussifioatlon of -oil.- The material that constitutes whe earth's crust can ~© divided into two broad catagories, -oil and Hock; where soil means a natural aggregate of mineral grains that can be separated by such gentle mechanical means as agitation in water, rock on the other hand is a natural aggregate of minerals connected by strong and permanent cohesive forces. Of course the boundary between soil and rock is quite an arbitrary one. during t is work we are concerned with the material, soil, only as defined above,. Keeping in view the fact that the properties of 2 soil vary widely from place to place, further classifi­cation became essential as more and more properties were studied. Moreover, classification helped the engineers to understand each other while discussing soils from various sources* Various systems of classification developed and the most wicisly used ones are: 1 1 . The vJ.3, Bureau of Soils Classification 2. The Public AoacA: Administration System 3. The A sa^ranae Classification for Air­field Projects 4* Civil aeronautics Administration Classi­fication l) The U.S. bureau of boils of the department of .agriculture has classified soils on the basis of the mechanical analysis, and hence is a textural classifi­cation. It has adopted the following definitions of soil coigona.-ts: For classification purposes everything above 0.05 mm. is loosely grouped as sand ana the silt and clay fractions . ^m-tide in mm. Pine Gravel {grit) Coarse Sand medium hand 2 to 1 1 to 0*5 0.5 to 0.2> 0.25 to 0.1 0.10 to 0.05 0.05 to 0.005 0.005 oiid below Fine Sand Very Pine Sand Silt Clay 1 ■ A . 31 o a no, ai&jjxas, Ear. (jjepartmon versity of Utah, 1949 /• are defined as above. After finding tiie proportion of these materials the proper descriptive term for the soil is found by the use of the b. S. Bureau of Soils Textural Classification Chart. As is quite obvious this classification does not take into account other physical properties of the soil and so will not help in knowing the soil-behaviour in the field. This classification will, however, indicate what supplementary tests must be run on the soil in the labora­tory, which will help to classify it on one of the follow­ing three systems, 2) The Public Hoads Administration System. - The Public Roads Administration has classified aubgrade soils into eight groups based upon the presence of soil constitu­ents, physical properties, and performance. The eight groups are designated from Al, A2, to AS. Their properties are given briefly below. Group Well graded, coarse, fine and binder; or ideal sand, silt end clay. Stable in wet and dry weather. High internal friction, high cohesion, no detri­mental shrinkage, expansion, capillarity, or elasticity. Group A-2 Similar to A-l but has too much or too active binder (soft and unstable) cr too little or inactive binder (dusty), A poorly graded mixture. Group A-3 Coarse material with no binder - a 4 clean sand - may be sta ilized with bituminous material or portland cement, . Group A-4 Silty soil with a minimum of coarse material or plastic clay. Absorbs water and looses sta­bility. Subject to frost heave. Found in glaciated regions. Group A-5 Similar to A-4 but is highly elastic* Contains mica or elastic organic material. Low stability -when wet. Subject to frost heave. Group A-6 Compressible clay soil without coarse material. Group A-7 -lastic clay soil without coarse material. (Hebounding clays) Drainable. To be used with care. Group A- 8 Similar to A-5 but has organic material such as peat or muck. Unsuitable for subgrades or embank­ments. High natural water content. Low internal friction, low cohesion, with detrimental capillarity and elasticity. Incapable of supporting a road surface without settle­ment . These groups h^ve been further subdivided. 3) Casastrande Classification. - In Casagrande chart there are fifteen group symbols, each having refer­ence to a specific basic type of earth material, The first letter of each symbol is either C (clay), 0 (gravel), 0 {organic silt, silt-city, or clay), S (sand, sandy-soil), or Pt (peat, highly organic fibrous soil). The second letter refers to gradation and other physical properties, and may be F (fines, material less than 0,1 mu), K (high compressibility), L (relatively low to medium compres­sibility), P (poorly graded), or W (well graded). The first soil types GW, GC, OP, GF, SW, SC, SP, and dF are rated from "fair" to "excellent" as foundation materials, The remaining seven, ML, CL, OL, MH, CH, and Pt are rated from "fair to poor" to "extremely poor" as foundation materials. The first eight soil types have a greater quantity of cohesionless material tban cohesive material, while the last seven types are predominantly fine-graded plastic materials. The first eight soil groups are relatively stable, low in volume change and non-plastic. The remaining seven groups are relatively unstable, high in volume change and plastic. The first eight correspond to the Public Roads Administration group classification included in groups A-l, A-2 and A»3, The remaining seven correspond to Public Hoads administration groups A-4 to A-8 inclusive. The Gasagrenae Classification is preferable to the oicer Public Hoads Administration classification since the latter is based almost entirely on laboratory tests, whereas, the former is based on performance in the field as well as laboratory testa. 4) Civil aeronautics Administration Classi­fication. - The Civil Aeronautics Administration Classi­fication is based upon essentially the same physical properties of the soil as the Ihiblic Roads Administration system with the important difference that a great deal of emphasis is placed on the drainage and climatic con­ditions existing in the field where the soil is found. These two factors are of primary importance in airport design. Here Soils are divided into classification groups ranging from i£-l to 1-1 1 , and a number of supplementary sub-grade and sub-base classifications are given based on the two factors mentioned above. Soil classification is determined by Mechanical Analysis, the iitterberg limits, Capillary potential, and the California Bearing Eatio. Thus, it can be seen that the soil can be classi­fied according to one of the above systems, depending on the use to which it is to be put. These classifications further indicate the wide range of soil types and the di­versity in their properties, necessitating in most cases individual studies for complete knowledge of the field behaviour of the soil. 7 8 STABILIZATION SJLncs the day man started to usa the vehicular form of transportation, he has tried to make better routes for his vehicles. He wants roads which will be usable under all weather conditions. The next problem arises when the weights of vehicles are considered. More and more heavy loads are being moved on our highways and highway subgrades must be built to withstand these loads. The foregoing classification system for soil show that all of the soils will not be suitable for highway subgrades because they fail to meet the above require­ments of weather and load. It is in dealing with such soils that we enter the field of soil stabilization. Soil stabilization has been defined in different ways by different engineers at different times, anc this term has been used loosely. But now it generally covers the entire field from consolidation of soils at optimum moisture without admixture to the latest developments in using soil-cement, soil-bitumen, soll-lime, and all the other admixtures. The definition of soil stabilization as given by C. A. Bogentogler of the United States Bureau of Public Roads is as follows: The purpose of soil stabilization is to provide road soils with enough abrasive resistance and shear strength to accomodate traffic under prevalent weather conditions without detrimental deformations. Thus the problem of soil stabilization resolves itself into a process of increasing the shear resistance of the soil, and also making it weatherproof. Increased shear resistance means greater cohesion between the con­stituent particles. This cohesion may be due to molecular attraction between particles or due to mechanical inter­locking between them. The former is achieved by using admixtures to provide adhesive films between particles. For weatherproofing the main factor faced is water. **ater, once it gets inside a soil mass, plays such an important role in its subsequent behaviour that its stuay has become fundamental, and soil stabilization may be said to be moisture control of the soil. Water in the soil may exist in two forms - adsorbed or free - with regard to its adhesion to soil particles. It may be gravitational, capillary, cohesive, or solidi­fied depending on the performance of the water or the properties it Imparts to the soil mass. 2 2C. A. Hogentogler and 3. A. Willis, "Stabilized Soil Roads", jublic Roads -.■■a&azlne. Vol. XVII (1936) ppf 45-64. Let us consider the water adhered to the particles i; a soil mass, Adsorption is the phenomenon that causes all solids to tend to absorb or condense on their surfaces any jases or vapors with. which they are in contact, .'.hen absorption irvolves reactions that are essentially chemical or ionic in character it is termed base exchange. These phenomena depend upon electrical attractions. The power that plastic clays possess of retaining their plasticity when mixed with sand or other non-plastic materials is caused by the absorption of one solid by another. The clay is not distributed uniformly through the pores or interstices of the coarser particles but most of it forras a coating on the non-plastic material and many of the pores remain unoccupied even though there is more than sufficient clay to fill them. The smaller the particle size the thinner are the adsorbed films of water around them. In a colloidal suspension the soil particle may be considered as encased in a film of electrically adsorbed water, or water of hydration, and suspended In a body of free water (see Fig. 1). The properties of free water differ considerably from ttose of adsorbed water. Free water has all the properties of ordinary w ter, while adsorbed films have higher boiling points, lower freezing points, greater 10 surface tension, and arc more viscous than free viator. 11 iigure 1 It may be considered that the properties of the outermost layer of adsorbed films of water are sore nearly llice those of free water, and that the properties of the innermost layer are more nearly like those of solidified water or ice. within the thickness of the film all the properties from those of free water to ice would then exist. The extent to which the performance of soil will be influenced by free water and film water depends upon the moisture content of the soil and the surface area of the soil particles. The lower the moisture content at equal grain size and the finer the soil at equal moisture content, the greater will be the influence of adsorbed water. Gravitational water is free water that percolates into the soil by gravity during rains and thaws, while capillary water is free moisture drawn up through the pores of the soil mass from the water table by capillary forea. Capillary rise depends on the adhesive attraction Letweon soiJ and water, the surface tension of water and the size of pores in the soil. For ecpual adhesive at­traction, the height of capillary rise increases as the diameter of the ports decreases. It may also be noted that rat# of rise of capillary water depends on pore size wafet>g, and so in granular soils, which have larger pores, the height of capillary rise will be lower but will be attained earlier tinn in the case of clay-soils, where pore size being smaller the ultimate height reached by capillary water will be much higher but will take a longer time. To illustrate how changes in the amount of water affect the performance of a soil, let us start with a small amount of soil shaken up thoroughly in water so that the soil particles are aispereed throughout the water. If the soil suspension is set aside for some time, the soil particles will Settle down to form a sediment which will be very high in moisture content. The sediment will have all the properties of a fluid inasmuch as it will deform ana acquire the shape of any vessel in which it is placed and its density may be measured with a hydrometer. Thus In this state the ratio of free water to adhesive water around the soil-particles is so great that the performance of the mixture is domin­ated by the properties of free water. As the moisture content of the soil is reduced, the consistency becomes that of slips and slurries and although it will still deform under its own weight and adopt the shape of the vessel in which it is placed its density cannot be measured by a hydrometer. Thus the soil is in a viscous state. The minimum moisture content of the soil in this state is the true liquid limit of the soil. The liquid limit as defined by iitterberg, is some­what less because to determine this test constant force is required bo move the soil which does not flow under its own weight. When the moisture is reduced further the con­sistency of plastic soils is so changed that they become pastes which require the application of some external pressure in order to change their shape. The ratio of free or lubricating moisture to adhesive moisture, while decreasing, is still sufficiently great to cause the lubricating water to dominate the properties of the soil. Upon further reduction of moisture, a moisture content is reached at which the properties of the soil are altered abruptly from those of a plastic paste to those of 13 a semi-rigid material -with a corresponding considerable increase in its bearing value. This results from tiie fact that the r tlo of lubricating to adhesive moisture becomes so reduced that the adhesive moisture abruptly becomes the dominating influence on the performance of the soil. Oil continued evaporation a stage is reaches such that any further loss of moisture doss not cause any re­duction in the volume of the soil mass. The moisture con­tent at this point is culled the shrinkage limit of the soil. Continued evaporation below the shrinkage limit causes the mobile moisture to recede in the pores leaving only the very thin more-or-less solid films, which may have thicknesses of only a few millionths of an inch. When all of the pore moisture is finally evaporated the adhesive films are reduced to a solidified state with molecular thicknesses. Such films are really ice since at the enormous pressures (estimated greater than 20,000 at­mospheres) under which they exist the melting point of ice 3 is according to Smithsonian ihysical Tables , in excess of 76 deg. 0, or 168 deg. F. It is because of these solidified water films that thoroughly dry plastic soils form cakes and clods instead of dust. 3 Smithsonian Institute, 1933 ^mlthaoniaa -tiffsloal Tables, 8th revised edition, Washington, D. G. 14 Tims, generally speaking, stability in o soil can be acc0ffi.p4.isnea by either of the following two methods: a) by providing the soil with coarse and fins materials of the proportion and character required to produce stabil­ity, if necessary, supplementing this treatment by cfeomical admixtures to maintain the stability thus produced; b) by incorporating water insoluble bi.-ders in fine grained or poorly graued soils and consolidating the soli ir. a parti­cular manner to provide structural stability* The sur­face may then be covered v.ith thin we rirq courses to furnish resistance to abrasion. The control of moisture during compaction in both the above cases is, however, quite essential. The methods of aoil-stabilizetion, and kind of admixtures useu are: A) 'uy mechanical means This involves use of mineral aggregates ead soil constituents of the character and sizes required to make graded mixtures stable. This is & means of providing better Mecha.r,lcel interlock among the particles. Let us see how granular particles and binders are affected by traffic. The vehicle wheel will sink into surfaces of either pure dry sand or soft sticky clay. But the granular particles will tend to compact, whereas the clay a will never loose the tendency to displace under 15 traffic and form rate. How if a email amount of clay i(? mixed with, granular materials the affect of the vehicle will be tc force the sand grains cloBer together and the clay will help to bind them together and thus the road may, under /roper conditions of maintenance, develop a very dense surface under traffic alone, f-uch a surface would serve well If moist, but if it is dry, the binder becomes powdered under traffic and not only forms dust but also parasite raveling of the surface which leads to surface roughness and eventually to complete disintegration. B) By chemical means a) Use of moisture retentive chemicals such as calcium chloride and common salt to provide soil binders 'with enough moisture to facilitate the compaction of graded mixtures by traffic. Thus surfaces, which can be maintained in demp or slightly moist state will become compacted into very hard road sur­faces because the binder will prevent the separation of the granular particles and the shocks and blows produced by vehicle wheels then become effective in wedging the granular fragments into close association. / The importance of maintaining the proper amount of moisture cannot be over3tressed. While the absence of moisture from soil road surfaces causes dust and ravel­ing, too much moisture causes rutting. Iso, the drier the road surfaces become between rains, the >tter they 16 become during rains. This is because extreme dryness causes the development of small cracks in the binder through which the rain water has access to the interior of the mass and thus causes the softening of the road surfaces. No such fissures would be formed in damp surfaces of properly graded soils, and so rain water will be shed from them without injurious effects. It is the function of the deliquescent chemicals to help maintain moisture in the top surface. a) isolations of electrolytes, such as calcium chloride, sodium chloride, sodium hyposulphite, etc., to reauce the thickness of adhesive moisture films on soil particles and thus proviue stabilised mixtures with greater density. b) Primes and fillers such as soaps, stone dust, and slag to increase the adhesion between mineral constitu­ents and the chemical and bituminous admixtures, and thus assist In retaining the benefits the admixtures were ex­pected to furnish. c) Neutralizes such as limestone dust, slag, hydrated lime, etc,, that serve to alkaline acid soils and thus prevent the loss of stabilizing chemicals caused by detrimental base exchange. 0 ) stabilization »xth c^ementln^ materials In this method water insoluble binders such us Portland cement and bituminous materials are useu. These f.u. r■» ni*s h" ■ * ■f* ilms 17 more substantial than those of moisture alone, and by coating the particles they help to make the mass less susceptible to moisture effects. Also they permanently destroy the colloidal properties responsible for detri­mental volume change in soil mixtures. Thus the use of insoluble adhesives is not expected or intended to render the soil sufficiently hara or tough to resist the abrasive action of traffic, but simply to render the soil resistant to water and thus retain the same bearing strength that the soil possesses when in a dry compacted condition. 18 Lr:s lu soil 2t.,b: isation i?rom tlie previous discussion on soil stabilization it is 3een that lime can be used for stabilization of soils. What does lime do when it is raixed with soil? There are varied opinions regarding the action that takes place be­tween lime and the soil vhen the two are mixed together. Some explain it by base exchange theory, which can be put down as follows: A colloid that holds hydrogen adsorbed on its surface is termed a hydrogen ionized or H-eolIoid. One with calcium adsorbed on its surface is termed a calcium ionized or Ga-colloid. If a substance like hydrated lime Ca(0K)o Is leached through soil conui^ing E-colloids, the calcium replaces the hydrogen to form Ca-colloids and the hydrogen thus released combines with the released (OH) to form water. Thus a base exchange has taken place. 2 The acidity or alkalinity of any solution is measured by its pH value. The pH value, which is used to indicate the concentration of hydrogen ions, equals the reciprocal of the logarithm of the grams of ionized hydrogen per liter of solution or suspension. Thus the total ionized hydrogen in grams per liter equals 10^% 19 and so the greater the pH value the less the hydrogen. concentration and less tho acidity of the solution. Distilled water has a pH value of 7. The lower the pH value below 7*0, the greater is the acidity of a liquid and the higher the pK value above 7 > the greater the alkalinity. The more acid the soil the greater its base ex­change capacity and consequently its corrosive properties. Clays high in silica termed "podzols" are acidic and con­sist principally of the highly water adsorbent scale-like particles that have high plasticity and shrinkage values, Soils high in iron and alumina, termed "latarites" are alkaline and consist more of the bulky or spherical particles. The best way to insure that detrimental exchange will not occur is to have the soil mixture alkaline, Limestone dust and granulated slag see;* admirably suited for use as pre-treatments or with other admixtures to neutralize acid soils and thus prevent detrimental base exchange. if Research in base exchange by Joseph and Oakley has shown that generally plasticity and shrinkage were 4 A. ?, Joseph and h, 3. Oakley, :'The Properties of Heavy Alkaline Soils," Journal of Agricultural Science. XL:: (1929), pp. 121-1 3 1. 20 21 greatest in soils aturuted with lithium ions, and as the kind of adsorbed ion was changed successively to sodium, magnesium, calcium, potassium, ammonium, and hydrogen ions, plasticity was gradually reducedj and the shrinkage was graduslly reduced as the kind of adsorbed ions were changed successively to sodium, magnesium, calcium, hydrogen, ammonium and potassium ions. This may help to explain the action of lime in reducing the shrinkage value and plasticity of soils. However, the opinions of Dr, Richard Bradfield and Dr, M. B, Kussell of the Department of Agronomy, Cornell University, are as below: It would appear that the most likely explanation of the effects of lime on road soil would lie in the fomation of ''natural cements" composed of calcium-alumlno- silicate complexes. The base exchange effect is probably negligible as the amounts of Ca{OH)o added 5/- by weight are greatly in excess of those required by the base exchange reaction. The high pH caused by Ca(GH)2 would favor the breakdown of many alumina complexes and clay minerals, t us in­creasing the amount of material from which the natural cement could be formed. Whether the effects are principally due to breakaown that is produced by the high pH or to the nature of the resulting ealclum-alumino-silicate that is formed could be , established by studying the effects of other alkalies, 5 Thus it is evident that no definite picture of the reaction between soil and lime can be drawn. 5 "Report of Lime-Boil stabilization GoMaittesM, Paper presented 45th Annual Convention of American Road TTu.ilj6i-t; - .i'UOtitT'tlnnv'^-rxrr^Tio" T^asiiihgibh: American iioad "Bullaers' ASS6cl?i'ti6fi, July, 194S). KISTOHT AIID DBT3L0P14I2TT OF GOXL-LBfJ MIXTURES Line hap been used oe construction material for buildings for centuries, and the Romans are known to have used quicklime for base construction in their road works. The August, 1945* issue of "American Highways" describes briefly the road construction methods and materials used in building the famous "Appian Way" in the most advanced stages of its construction, and from this article, it appears that lime was used In three of the five layers of the road which still remains one of Italy*s principal highway arteries today. The current usage of lima for road construction is a new development and the studies in this direction have not been carried very far. In the United states of America for the past fifty years lime has been used to a limited extant In cement concrete mixes in addition to Portland cement. Also hydrated lime has been used as a filler in bituminous mixtures and in small amounts of less than 1 in asphalt emulsions and cutbacks in order to improve the adherence of the asphalt to the aggregate in bituminous paved roads. 22 For the first time, the use of lime iit base con­struction was studied at the University of Missouri in 1924 under a fcatlGaal Lime Association fellowship. This reset*. oh was a ire 0 ted by .>e&n ii, J, iieCaustlaad, Director, ^ngijaeeriag Experiment station. The research project largely consisted of field tests, in which test sections treated with various percentages of hydrated lime v«ere established near £t« Joseph, ciouth Cedar City, Columbia 6 and Jefferson City, . isaourl, Results of these experiments proved that the addition of from three to six percent hydrated lime made cl«y roads containing assail amounts of aggregate reason­ably stable for one or two years. In addition, lime changed the physical property of the soil frao plastic to a relatively friable state which greatly facilitated completion. Also, lime had a tendency to reduce the fomatloa of xaud and ruts end to prevent surface stickiness under the wheels, iiaintensnoe could be ©ore easily accomplished because thare was no formation of a hard crust on the sur­face before the road was dry enough for dragging. It seemed that the dust nuisance was not by any aeans reduced 3. - cCaustlaad, "Lltae in h'irt iioads*, Pro­ceedings ^.tluiiul ^ix,xe ccmyeatioa. 1925. 23 in some cases it might have been increased. Treat go depth of six Indies was recommended, although no marked differ­ence appeared in the results brought about by the various depths of incorporation. In 1925j Croldbeoh reported the results of labora­tory experiments which show eel that additions of five per­cent of hydrated lime and Port lend cement have the effect of decreasing the volumetric change caused by variations in moisture content tied likewise of Increasing the bear­ing value of plastic soils that contain up to their limit 7 of capillary moisture. In India and Burma where molasses has been used as a soil stabilising agent, it has been claimed that the incorporation of Hue would prevent the washing off of molasses during the rainsf Molasses being soluble in water, any water percolating through the soil carries it away in solution. Molasses has a great hygroscopic property to keep moist and an adhesive quality to act as a good binder, while the chemical action of lime with molasses produces tricalcium suorate, a chemical that is insoluble in water. Investigations on stabilization by lime in the 7 'A. T. Goldbeck, "Research on the Structural Design of Highway by the U, S. Bureau of Public Roads", Trans­actions A,B.C.S., Vol. XXCVII1 (1925) pp. 264-300. SLi Mo Chih, "Research on Soil Stabilization", Proceedings highway Res.arch Board, Vol. XXIII (1940) p. 413. 24 National Tslang Hua University were aade on silty soils preveiling in the North-Western. part of China, Artifi­cial silty soils were ± repared from tv.o different local soils in the vicinity of Kunming, Cement was used as a stabilizer for comparison and wetting and drying tests (eight cycles) were run. It was concluded that cs-ent was a better stabilizer, particularly in email proportions, end the amount of incorporation of lump line with silty soils should be well over ten percent In the Unit:d 'tates after the work at Fissoari (page 23), nothing much was heard about llae until 193S, when the Texas Highway Department became Interested end started extensive laboratory tests on different south­western soils with different percentages of lime, A chemist, F-henscn D. Losesne, carried out the work, both 10 in the laboratory and in the field. The tests ware run only on clay soils, and his inves11gat1on indieat ed that the use of hydrated lime for stabilizing heavy or sticky clays Is better than uay other stabilising agent, end it lo the only inexpensive stabilization agent which is capable of producing such desirable changes in clay soils when used in small quantities of from one to five pere ent. 25 %>lo Ohih Li, "Research on Soil Stabilization*, Proceed.inas highway Aeseareh Hoard. Vol. XXIII (1940) p, 413. ^Sherman 0, Lesesne, Pamphlet "Stabilization of Clay Roaabeds with Lime", National Lime Association Publication, i;LIbid. In these tests eighty-three different clays were used, *r:,u ti;.e soils tested were from Oklahoma, Louisiana, Mississippi and Texas. One hundred and fifty pilot specimens of '-•lay a-ere prepared and aixed with various percentages of nydrated line and moisture. Oven dried clay samples, sieved through a somber 10 sieve-;, were used. Optimum moisture content for various percentages of line-cl ay mixture "rr: -^armined by the American Association of 8ta* - '"\ghway Officials Standard Compaction Test. The test samples ware then molded at these optimum riois I ; *. - truants in stendard noli in two layers, one and one-half laches thick, subjecting each layer to twenty-five blows. The molded samples were suhjwotod to capillarity In tr.;:., for twelve I m k , after which they were placed on moist filter paper* After one, sevan, 'twenty , .<:r1 thirty days the samples were tested for stability by pm'tohiap on the :oici slue with a blunt needle, having one-twentieth of a squars in oh surface, . and the pressure required to cause the needle to penetrate one-quarter of an inch into the specimen vtnz noted. The following results in a gumbo cloy with a plasticity index of 45.3 were obtained: TABLE i RU3ULTS OF T ^ cT J PERlfO&iiSD Oil A 7SRT PL..1SVIC GU130 SLaY Llzae Days in Penetration Value Percent Capillary Tgaji lbs. par sq. in, 5 1 2,000 5 7 4,000 5 20 4,400 5 30 4,400 0 7 20 5* 7 150 •Dried immediately after molding and placed in the capil­lary tank. The in physical pi*op<sri*iea of tnis gumbo clay are givon balow. TA5L& 2 L/F3CT OP Ott P L .ijii 1 0 GUMBO CLAx Physical Constant Untreated Olay with Olay 5% Lime Liquid Limit 74 43 Plasticity Xn&ex 45 5 Pleld Moisture Equivalent 45 43 Centrifuge Moisture Equivalent 4& 31 Shrinkage Limit 12 31 Shrinkage Ratio 2.uQ 1.46 Linear Shrinkage 23.6 5.2 Soil Binder Present 97.3 - Results of another medium Texas clay with a plastic index of 1 1 .4 are shown in the following tables. This is typical of the behaviour of clay with a plastic index in this range. 28 TABLE 3 RESULTS OF T 13TG OH A MEDIUM CLAY Lime Days in Penetration Value Percent Capillary Tank lbs. per aq, in. 5 7 3,200 5 7 4,500 0 7 190 *Dried Litwediatelj aftor molding and placed in the capil­lary tank. The ukaraotejL of thi- vie.,* changed by the audition of the lime shown in the following table: TABLE 4 EFFECT Of LIME Oil MEDIUM CLAY Physical Constants Untreated Clay 5% Lime I<iquiu ijiikxt 31.9 3o*0 Plastic Limit 20.5 32.0 Plasticity Index 11*4 4.0 Field Moisture Equivalent 25.9 32.1 Percentage Soil Binder 31,6 ----------- Shrinkage Limit 15*3 26.4 Volume Snrrnkage 23. ^ 10*1 Shrinkage Ratio 1.87 1.52 Linear Shrinkage 8,5 3 .4- Centrifuge Moisture Equivalent 23.6 20.6 In each caae, one of the specimens was dried be­fore placing in the capillary tank. The bearing value was greatly reduced, indicating tl? ,.t it is deairable to moist-cure mixtures of lime and soil in order to develop a maximum stability. Mr. Lesesne recommended the following procedure for stabilizing clay fox- roadbeds vjitli tiie use of hydrated lime: first, the clay should be mixed intimately with about 2 to lOp of hydrated lime (dry weight basis), and with the optimum percentage of moisture present, the road­bed should be thoroughly rolled; second, the roadbed should be covered with the asphaltic topping as soon as possible to prevent evaporation of the water and thus atop the exchange adsorption between the lime and the clay. The topping will retain permanently the moisture in the lime-treeted clay roadbed. The theory advanced by Lesesne for vhe reaction between lime and clay is that when these two substances are mixed together there is a tendency for the adsorption of lime on the surface of clay particles. Bvit this ad­sorption can take piece only if moisture is present. Thus water is essential for the completion of this re­action and any surface made up of soil-lime mixture should not be allowed to dry out. Further, this adsorbed lime on the clay particles also affects the thickness of moisture films covering the particles of clay, It keeps these films very thin. These thin films of moisture are very viscous and act as a binder for the clay particles. This is another reason why surfaces of soil-lime mixture should not be allowed to dry out even after the adsorption reaction is complete, Mr. Chester McDowell, Senior -Soil Engineer, Texas Highway Department worked on lime stabilized mixtures and adopted the triaxial compression test for determining the stability of such, mixtures. In his tests, the mixtures are compacted in a standard molu to densities comparable to those obtained by rolling in the field. After mold­ing specimens are weighed, measured for height, removed from mold, moist cured seven days, and dried for one day in an oven at 140 degrees I'ahreln&eit. Than ceils are placed around the specimens, which are then subjected to capillary wetting for ten days, and finally tested in compression in a triaxial compression machine at various lateral pressures, From the test data, on average, good quality flexible base materials, stress-strain curves and Mohr's diagram are plotted. The rupture envelope is then drawn to these Mohr's diagrt is. For satisfactory soil-lime mixtures the results should give a plot above the rupture envelope for average, good quality base material,^ McDowell's explanation for the action between lime and soil is as follows: 12 Chester Lcl/owell, ''Progress Report on Develop­ment and Use of Strength Tests for Subgrade Soils and Flexible Ease Materials," rrocoedin/.-s Highway Research Board, XXVI (1946), p. 4S4. 30 Many natural soil materials contain pozzolanic sub­stances which react with lime solutions at ordinary temperatures to form stable, oementitious compounds. Pozzolanas have been described as high siliceous sub­stances, often of volcanic origin, Dlatomaceous earths or shales and many clays, notably bentonite, must be in­cluded. They may be composed of silica, silicates, alumino-silicates, or a mixture of these, in an amor­phous, glassy state. Combination with lime forms stable gels, whose stability is not impaired by leaching...the reaction between lime and pozzolanic soils continues over a long period of time. The clay has, in some in­stances, been burned with the stone to produce a lime. In other cases, clay and regular hydrated lime have been aaded to granular materials to form this mixture desired. The strength of such mixtures appears to be considerably in excess of that of ordinary lime-sand mortars made without the addition of Portland cement.... the firm samples consist of lime ana pozzolanic soil whereas the weak, crumbly specimens consist of lime and sand. Thus it Is seen that lime does not have any action with sand to improve the xaixture. mockery and Manigault reported reduction in plasti­city index and lineal shrinkage accomplished by admixtures of lime to soil and base course materials. Three percent of lime was sufficient to improve otherwise unsatisfactory base materials to the extent that they conformed to base 14 ' course specifications. A black clay soil treated v,i«h 8.5$ of lime had a plasticity index of 7 as compared with 41 for the raw soil. According to maaig&ult, ‘'This day after treatment no longer looks or acts like clay, but resembles a soft fine-grained 31 13Ibid. 14-W, D. Dockery and i). iS. H. Manlgault, "Lime Stabilization and Low Dost Road Construction", Hoad and Streets Laaazine. Vol. XC (1947) pp. 91-95. sandstone."1'' This condition of the soil will facilitate compaction and a higher density may be obtained, Freebourough has also reported the results ob­tained by adding lime to very plastic clays as shown in the following table • TABLE 5 EFFECT OF LIME OH A VERY PLASTIC CLAY Treatment Average L. L. Untreated 80 4'> Lime 56 8f> Lime 49 Hoad Construction with Lime • » J • - ' Efforts to stabilize fine-grained soils by admixtures of lime and cement materials were made in Iowa and South Dakota as early as 1924 and in Ohio several years later. The results of early work were not particularly promising but they should not be considered indicative of the possibilities of such treatments because the requirements of thorough distribution of admixture, high degree of compaction, and protective surface treat­ment now deemed necessary were not recognized in the earlier work. 15Ibid. l6B, B. Freebourough, nLime Treatment Permits Use of Substandard Flexible Base Materials,n rubllc orks magazine. June, 1947. 32 Average Average P. I. L. S. 52 25 20 13 12 8 Practically all the recent and present construction of roads using lime has been carried out in Texas. Lime was first used in Texas in connection with the rebuild­ing of sections of highways that had failed because of the excessively high plasticity index of the binder. These projects were part of the regular maintenance operations. In one case the average r. I. for the section was 18 and the percent of soil binder was 35. Admixture of three percent of waste lime with the top six inches of the existing base material was proposed, Samples taken from the road mixed material indicated that the resultant P. I. was 8 and the percentage of soil binder was 27. The existing road was first scarified, and one-half of the material was windrowed to the sides and the other half to the center of the road. The center windrow was then flattened on top and the required amount of lime uni­formly spread on the pile by dumping from a truck with the tail gate partially opened. The material was then bladed out until a uniform mixture was obtained. During blading the mixture was also sprinkled with water to approximate optimum moisture as previously determined in the labo­ratory, Addition of lime made the material friable and so the mixing was easy. The road was then compacted. After compacting the first course the remainder of the material was pulled on 33 the road and worked in the same manner. After this com­paction, the road was maintained in a moist condition for four days and then a triple asphalt surface was laid. Another repair job was carried out on U.S. 81 near Hound Eocii, Texas. Along the repaired section the exist­ing selected material had an average P. I. of 24 and average percentage of soil binder was 39. This material being very poor, it was used only as subbase and four inches of good material was placed over it. A combination of materials was used as follows: $ of Mixture P. I. $ S. B. Pit run Gravel 88 22 18 Caliche 12 10 79 Resultant mix 100 17 25 The gravel caliche and lime were dry mixed first, and then carried to the road, wetted, compacted, moist cured and then sealed with asphalt. The resultant mixture of gravel, caliche, and lime had a plasticity index of 5 and 22 percent of soil binder. An older and interesting example of base course stabilization with lime is the paving on the runways and taxiways at Chase Field, Beeville, Texas, constructed in 1943 by the Civil Aeronautics Administration and the Corps of engineers. Crushed caliche with a maximum plasticity index 34 at 10 was specified for the base course on this project. The only material available within a reasonable hauling distance had an average plasticity index of 15. The laboratory tests indicated that this plasticity index could be lowered most economically to meet the speci­fication requirements by the addition of two to three percent of hydrated lime. Actually two percent was used in the mix resulting in a base course having plasticity indexes ranging from 2 to 8 , and an average of 5« The pavement consisted of six inches of plastic A-2 soil as a subbase, eight inches of lime treated caliche base course, and two inches of rook asphalt sur­facing. The lime was mixed with the windrowed caliche by means of a traveling plant and then compacted with sheeps-foot roller§» Owing to the difficulty of maneuvering the traveling plant, the fillets at the intersections and an intersection area did not receive any lime treatment. An inspection of this work in April of 1948 disclosed that the runway and taxiways treated with lime are in excellent condition, while the untreated areas are in very poor con­dition. Untreated service roads have also deteriorated. Since these original constructions in 1945, the Texas Highway Department has constructed nearly 75 miles of roads using lime as an admixture in base course. The . 35 original constructions built nearly three years ago are still in very goou condition. Lime In Bituminous fixtures Lime has been used as a filler in hot bitumi­nous mixes, and it has been used with asphalt emulsion to 17 T stabilize soils on runways in England. It has been indicated by those who have used lime with cutback asphalt that the lime facilitates the dispersion of asphalt and may possibly permit the reduction in the quantity of cut­back required. Use of lime in soil stabilization has shown quite encouraging results. But until now its use has been limited to very plastic clays. Further research in this field will develop interesting and valuable information which may open a new way for lime in the construction of low cost roads. 36 •^Robert L. James, "Soil Stabilization - The Wet Sand Process," Contractors Record and l-unicjpal Engineer­ing. February 6 , 194o. CONSTRUCTION METHODS FOR SO XL-L IM S ROAi S. Lime stabilization has been accomplished by the same road mix methods used in other forms of soil-sta-bilization. First the soil in the road bed is scarified by means of scarifiers to the specified depth and this loosened material is then thoroughly pulverized by using disc harrows. The lime is then uniformly distributed on this pulverized soil from a gravity or presatire distri­butor, in such quantity per 3quare yard that after mixing the desired percentage is obtained in the resulting mix. Disc harrows, motor graders or motorized blades are then used to mix lime thoroughly with the soil. Care should be taken at this stage to see that mixing is uni­form throughout. Water is then applied using a sprinkler truck. This equipment should have a fine spray and cali­brated tanks. The water is thoroughly mixed and more may be added "until the moisture content reaches the optimum value, as determined in the laboratory for that percen­tage of so11-lime mixture. When the mixing is completed, the mixture is com­pacted to predetermined density by a sheep*s-foot roller, or a pneumatic tired roller. The surface should then be finished to correct grade and camber by using a grader or blader. For final compaction a smooth steel surfaced roller may be used* In order that the moisture in the mixture does not evaporate and is retained until the reaction be­tween soil and lime is completed, the wearing surface should be placed as soon as possible. If the wearing course Is delayed the road should be moist cured continuously for seven to fourteen days by frequently sprinkling the sur­face with v^ater. The wearing course on these roads is usually some type of bituminous surfacing. PRESENT INVESTIGAT10NS Problem As is obvious from the foregoing discus­sion, the use of lime has so far been limited to clay soils which had very high values of plasticity index and lineal' shrinkage, and so were found to be unsuitable for use in highway subgrades. Thus the experience to date has shown that the use of hydrated lime for stabil­izing heavy or sticky clays is better than any other sta­bilizing agent. Thus a low cost but durable bed for roads could be produced from the soil present at the site without Incurring the expense of purchasing and transporting sand or gravel* The purpose of this Investigation was to study the effect of hydrated lime on silty soils, and to find the answer to the following questions; 1 * What are the age-strength characteristics of these soil-line mixtures as they are cured by capillarity, 2. How does lime affect the capillary absorption of water by the soil. The tests were conducted in the laboratory on four soils, three predominant In silt size particles and 39 one pure sand. Samples were molded with four percent lime at optimum moisture content, and then curod in a moist cabinet by subjecting them to capillary vetting. They were tested for unconfined compressive strength In a compression machine. The various details of the experiment are given on the following pages. 40 Tests Classifications of Soil Samples - Various tests for tiie classification of the soil samples and for the determination of their physical constants were run. No tests for physical constants, however, were run on soil samples mixed with four percent lime as the values for liquid limit, plasticity index, and linear shrinkage were not high for the raw soil. Their effect was not considered to be detrimental for any structure where the soils may have to be used. Determining Hygroscopic Moisture Content - As calculations in the soil and soil-lime tests are based oxi the oven dry weight of the soil, the hygroscopic moisture content was determined for each soil for the portion passing Number 4 sieve. Approximately 100 grams of soil carefully selected from the sample of pulverized soil were placed in a moisture can of known weight. The soil sample and can were weighed to the nearest one-hundredth of a gram, and the can with its lid open was placed in the drying oven at a temperature of 110 degrees Centigrade. After drying the sample to constant weight, the can was removed from the oven and allowed to cool with the lid on. After cooling to room temperature the can and soil were weighed again. The hygroscopic moisture was computed from these air and oven-dry weights of the samples. 41 Determining Moisture-Density Relations of Raw Soil.- Moisture density relations of the raw soil were determined in accordance with American association of State Highway Officials. Method T 99-3B (See Appendix III, page 1071 which is based on the compaction force of a 5»5 pound metal hammer dropping twenty-five times from a height of twelve inches onto each of three layers of soil. The mold used is 4 inches in diameter, and 4.59 inches in height with a volume of 1/30 cubic foot. Determining Moisture Density Relations of Soil - Lime ilixtures.- An air-dried soil sample was taken, pulverized and passed through a Number 4 sieve. From this pulverized sample 3000 gr ms of soil were taken, fetaua, and knowing the hygroscopic moisture content the dry weight was calculated. Hydrated lime equal to four percent of this dry weight of soil was weighed and in­timately mixed with the soil sample, Moisture density tests for this mixture were run in exactly the same way as for raw soil described above. The mixture was sub­stituted for the raw soil. holding the Specimens. - About 2000 grams of air-dried soil ere weighed, and knowing the value for hygroscopic moisture, Its dry weight was calculated. An amount of hydrated lime equal to four percent of this dry weight of soil was weighed out and mixed thoroughly 42 43 with the soil. To calculate the amount of water to be added to to this mixture, allowance was made both for hygroscopic moisture and loss of moisture due to evaporation and con­tact with the containers and the trowel. The following sample computation illustrates the calculations. Sample Calculation for water to be -added to fixture eight of air-dried soil taken Hygroscopic moisture in soil Oven-dry weight of soil Hydrated lime required at t.eight of total mixture Optimum moisture content for mix Hygroscopic Moisture present Allowance for evaporation etc. Net water to be added Volume of water to be added = 2000 gins. = 1.25b * 2000(1-1.2) = 1976 gEUS. - 1976 x .04 = 79.04 gas. * 1976 + 79 = 2055 gas. = 18,0$ = 1.23& * 1.0% = (18 - 1 .2 ) + 1.0 = 17.8$ = 17.6 x 2055 ml. 100 365.79 ml, This araount of water was added to the mixture and thoroughly mixed with a trowel until a uniform distrl- but ion of water was obtained, ifor molding specimens the same mold and collar ware used as for determining moisture density relations, from the mixed material prepared, enough materiel to form a compacted layer si.ghtly more than one-third of the specimen height was placed in the mold. The layer was then compacted by di'opping a $.5 pounds hammer twenty-five times from a height of twelve inches. The hammer blows were spaced as uniformly as possible over the entire surface of the layer. After the compaction of this layer its surface was lightly scarified by marking criss-cross lines about one-eighth inch aeep and spaced half inch apart. This was done to provide bond with the succeeding layer. The second layer of mixture was then placed and compacted in a similar way, and the separation planes scarified. The third and final layer was so placed and compacted that the soil extended into the collar. The collar was then carefully removed, and the upper surface of the specimen was finished to a true level plane by scraping away excess material with a steel straight edge. The specimen was then weighed with the mold. This weight was recorded with the tare weight of the mold. The base plate was next removed from the mold and the specimen was carefully extruded by using a hydraulic 44 jack. Care was taken that the edges of the specimen ware not damaged. Five specimens of each soil sample were thus molded. Curing the Specimens.- Of the five specimen molded four were subjected to curing while one was tested immediately. The samples of soil Number 1 were subjected to capillary curing immediately after molding, while the others were kept in a lOOjo humid cabinet at a temperature between 65 dag. to 70 deg. F, for the first twenty-four hours and then subjected to capillary wetting for the remaining period. For capillary wetting the samples were placed in a moist cabinet on a device shown in detail in Ap­pendix. iy, page US* The temperature of the cabinet was maintained at 6$ degrees F to 70 degrees I'. The water level inside the wetting device was checked from time to time and more water was added when necessary (Fig. 2). Testing the Specimens.- One specimen of each soil-lime mixture waa tested In a compression machine (Fig. 3) immediately after molding, while the rest were tested at intervals of seven days, fourteen days,, twenty-one days, ana twenty-eight days of curing. Before testing, the samples were weighed, so that the quantity of moisture absorbed'could be computed. 45 46 j'ig. 2 Sampias in Moist Cabinet on Wetting Device, 47 Fig. 3 Testing Specimen in Compression Mashine < After weighing, the samples were allowed to drain for half an hour at room temperature. After weighing and draining the specimen was placed In the compression machine. The load was then applied at the rate of 0,05 inch per minute until the I sample failed by cracking, U'ig. 4) or the load indicat­ing needle of the compression machine dial started to retreat. The maximum value of load thus reached was recorded as the compressive strength of the specimen. jj'ig. 4 Samples Failed, in luaooafined Compression Test. RESULTS AND DISCUSSION. The results of the experimental work have been included in the appendices. Appendix I covers the classi­fication and compaction data for all the samples, both for raw soil and the soil-lime mixture. Appendix II gives the experimental test data in detail. Appendix III gives the standard test for moisture density relations (A,A.S.H.O. Des. T99-38}, while Appendix IV gives the details of the set up for capillary wetting of the specimens. For facility of discussion of test results, summary test data has been given in Tables 6 and 9 on page 54, and necessary graphs have also been plotted ( see page 55, 56, cuad 57*. It has already been pointed out that in this investigation eaa the strength-age characteristics of a four percent 1 line-soil mixture, and the effect of lime on capillary absorption of the soil have been studied. Pour soil samples were used, three of which, as the classification tests indicate, are A-4(8) on the Public Roads Administration Classification System, while the 50 fourth one is sand and hence is of A-3 group. All samples except one are predominantly silt, Sample 1, which came fro® the area between the Engineer­ing Hall Building and the Physical Science Building on the campus, contains 38-s sand, 50% silt, and 12% clay, sample 2 collected from the rear of the Naval Science Building consists of 21$ sand, 75^ silt, and 4;l clay, while Sample 3 obtained from Interstate Brick Company has 32,15/0 sand, 75*5>u silt and only 2,35^ clay, TABLE 6 OPTIMUM MOISTURE AND MAXI UM DRY DENSITY FOR HAW SOIL Soil Sample Optimum Moisture Max, Dry Density Content lbs, per cu, ft. 51 1 15,2 113,0 2 17,4 110*5 3 19.3 110.0 4 13.1 112.5 TABLE 7 OPTIMUM MOISTURE AND MAXIMUM DRY DENSITY FOR SOIL-LIME MIX Soil Sample Optimum Moisture Max, Dry Density - 4%' Lime Content lbs, per cu. ft. % 18.5 1 20.2 104,3 2 21.0 105.3 3 9.5 104.4 4 117.5 Prom a glance at the moisture density relation data(Tables 6 and 7)for raw soil and soil-lime mixtures it is seen that for every sample except sand the value of optimum moisture for the soil-lime mixture is higher than that for raw soil alone, while the maximum dry density is lower for the soil-lime mixtures. This is probably because the specific gravity of lime is less than that for the soil, and so the weight per cubic foot of the mixture will be less. Since the addition of lime increases the surface area of the particles in the mass, more water will be required to furnish the lubri­cating and adhesive films of moisture round these particles. In the case of sand the reverse is true. The optimum moisture content for the sand-1ime mixture has decreased while the maximum dry density has increased. In this case the lime acts as a filler and so fills in the voids in the sand mass. Thus the mass becomes denser, and the density increases. Naturally as the pores get filled up moisture films get thinner and so the optimum moisture content decreases, tflSCOKFINSP CQMPRTl'SL IVS STRBMGTH Studying the compressive strength results of the soil-lime mixtures It is seen that all of them show the same general trend with respect to strength change except sand. It should be again pointed out at 52 this ftt&ge that in the case of aoil-eample 1 , the ■ specimens ¥»re placed on the- capillary seat k*a*Kl lately after oolcilng, while the other apeei&oim ware kept in the mtat cabinot end subjeoteo to a bumid at, -o sphere for fcho fir«t twenty four hours after molding* and only after this period were they subjected to capillary sot­ting and curing* The results in the ease of Sample 1, {Table 8), show, that the compressive strength has fallen from 46.2 p.s.i. to 15.9 pounds per square inch during the first seven days of curing, but after that period has increased to 23*85 pounds par square inch after fourteen days, 27.8 pounds per square inch after twenty-one days, and 30.2 pounds per square inch after twenty-eight days. The flattening of the curve at this stage indicates that the strength of the mixture will not substantially increase thereafter. The capillary moisture curve (page ) for the same soil-line mixture indicates a high rise in moisture content of the specimen during the first seven days, when it increased from 19.2% to 26.8^, but after that period the moisture content decreased steadily, and the value after twenty-eight days was 22.85®. This behaviour xaay be explained as follows: as suggested by Lesesne, lime is adsorbed on the surface of soil particles in this mixture of soil and 53 TABLI 8 m o w n u m ste^oth tsit data for soil-lii^; kxxtohbs iiays of Curing oaiupl© 1 oarapX© 2 iS&aple 3 ^as*i 0 ji • S * % < 4 6 . 2 55.7 32.6 19.66 7 14 p»0»i* p*s»i* 15.9 23.65 99.5 79.5 13.90 135.5 . 99.5 3.98 21 :;p. ».i. 2 7 .B I 157.5 107.5 3.96 28 i p.a.i. 30.2 : 169.0 115.2 3.98 Remark j H 8 1 g K i r » t » Capillary . . wetting after 24 lira.. .. in moist cabinet TABLE 9 CAPILLARY JKOXSTUBS DATA FOE 80IL-UUSB KXXttnOS Days of Curi. aVs.* .Sample 1 ^ai.'sple 2 .^aaple 3 {sand i >-Hiikpla4 0 ; * 19.2 7 f" I ; 26. 8 i 20.1 22.75 20.05 23.7 9.16 . i iu?5 ** . 25.9 I 24.4 24.8 11.8 24.6 24.3 i 24.8 i 11.8 f I 28 22.6 24*4 fieaark l,»y ea. Capillary. . wetting 25.0. . a fte r ......... , 24 hrs. in •?*>"* ••■■moist cabinet UNCONFINED COMPRESSIVE STRENGTH - POUNDS PER SQ INCH 55 CAPILLARY MOISTURE CURVES FOR SOIL-LIME MIXES Le gend o Sample I a Sample 2 7 14 ' 21 28 DAYS OF CAPILLARY WETTING n § # 6 PERCENT MOISTURE 57 CAPILLARY MOISTURE CURVE FOR SAND+ LIME o 7 14 21 28 DAYS OF CAPILLARY WETTING ' He* 7 lira©. The adsorbed lime affects the thickness of moisture films covering the clay particles. It keeps the films of moisture very thiii. It is possible that the reaction of the adsorption of lime does not start immediately after mixing with the soil, j^robubly it starts after some time has elapsed. The specimens, which were placed on the wetting device immediately after molding adsorbed almost enough water by capillarity for saturation in the first few days and this water probably retarded the adsorption of lime on the surface of soil particles so that in the beginning the lime was not effective In controlling the thickness of films of moisture around the soil particles. Thus the capillary water formed thick films of moisture around soil particles giving a high mobility to them and resulting in. low coxapressive strength when tested after seven days, after this period the reaction of the adsorp­tion of lime had proceeded so far that it was effective in reducing the thickn'esa of films of moisture around some of the soil particles, and these thin filws served as a binder for the particles. That is the reason for the Increase in compressive strength after a seven day curing period. The water, which was surplus, due to the thinning of the moisture films around particles, now existed in a free state, all this free water was drained out of the specimen by gravity. This explains the re- * 58 . 59 duetion in the moisture content of the soil specimens after the first seven days. It is evident, therefore, from the foregoing discussion that as the adsorption of lime on the surface of soil i>articls increases, the com­pressive strength will increase and the moisture content will decrease. One question still remains unanswered. Why the specimen absorbs a large amount of water during the first seven days while the other specimens, which have been placed on the capillary seat after twenty-four hours of humid curing, do not? The answer perhaps lies in the nature of the soil. This soil 1 contains the higher percentage of sand size particles (38$) than the other soils, and so the pores in the molded mass may be of larger diameter, causing a faster rate of capillary absorption. In the ease of other samples of soils 2 and 3, the maximum value of absorbed moisture is reached in fourteen days. It is very likely that the capillary moisture curve will also tend to flatten and run parallel to the horizontal axis after the lapse of some time, as is the case with other specimens. Considering soil samples 2 and 3> there is a marked Increase in their compressive strength as the samples ere cured. Soil sample 2 increased in compres­sive strength from 55.7 pounds per square inch on the first day to 169 pounds per square inch after twenty-eight days of curin , an increase of 207$, while sample 3 increased froia 32.6 pounds par square inch to 115.2 pounds per square inch, an Increase of 253$ during the same period of curing. It may also be noted that of these two soils, 2, which attained a higher compressive strength contained the lowest percentage of sand size pa - tides. It is further observed that the major increase in compressive strength, in the case of both the samples took place in the first fourteen days of curing. The increase was 14b$> for sample 2, and 144$ for sample 3. After this period the curves have a tendency to flatten out, but they definitely indicate that the samples would be gaining strength for quite a long time,thereafter. It may be concluded that there Is some reaction going on between soil and lime which takes a long time to complete. As discussed In the foregoing pages this reaction may be, either that of adsorption of lime on the surface of soil particles, or probably some kind of a ealciuci-alumino-flilicate complex is being formed which acts as a cement to bind the particles. 60 from the capillary moisture curve it is seen that after the first fourteen days there is no further increase in moisture content. In the case of sample 2, the increase in moisture consent during this period is from 20.1^ to 2l+,l$ an increase of 4.3$, which is the value even after twenty-eight days, whereas in the case of sample 3, the increase is from 20.05% to 24.8% during the first fourteen days and the value after twenty-eight days is 25.05&, thus showing an increase of nearly 5$* Correlating this study of capillary moisture with the results of the compressive strength d:.ta it is noted that practically all the water is absorbed during the period in which strength is increasing at a rapid rate and none afterwards. Probably the reaction be­tween lime and soil is most active in the beginning and more water is needed while afterwards the water already present in the specimen takes part in the reaction and there is no further absorption. In the beginning it is very likely that water is being taken up by the soil-lime reaction as well as being drawn up by capillarity. However, there were no means to measure these two differ­ent quantities so no attempt can be made to express them quantitatively. In the case of aand, the results are unsatis- 61 factory. The compressive strength for the sand-llme samples tasted immediately after molding was 19.88 pounds per square Inch; after seven days of curing it had de­creased to 13.90 pounas por square inch with further cur­ing it decreased to the low value of 3.98 pounds per square inch, which remained constant thereafter. From this it may be concluded that lime in this small per­centage is not a suitable or desirable treatment for stabilization of pure sand. The capillary moisture studies for sand show a very irregular behaviour, the moisture content sometimes rises and sometimes falls, iaore detailed study is needed for the use of lime with sand to arrive at conclusive results. Effect of Lime on Capillary Absorption - From the eapilla-y absorption curve of raw soils (page 65) it is seen that the trend of absorption is the same as for. soil-lime mixtures. The maximum absorption in the case of raw soils is, however, reached in the first seven days, after which the increase in moisture content is small• For sample 1, which was molded at 16.1 percent moisture content, the value after seven days was 21.5 percent, while after twenty-eight days it was 21.85 62 percent. Thus the total Increase in moisture content during capillary wetting was 5.75 percent, of which 5.4 percent occurred within the first seven days. The molcied specimen of soil sample 1, was placed for capillary wetting immediately after molding, and it is seen that while the soil-lime mixture for this soil first increased 7,6 percent in moisture content, and after twenty-eight days lowered to only 3,6 percent, the raw soil sample showed a progressive rise in moisture content during the entire period of soaking, and from the final values it is apparent that the soil-lime mixture absorbed less water than the raw soil. The raw soil specimen after capillary wetting of twenty-eight days had become very soft and on testing failed at a stress of 5*97 pounds per square inch, while the soil-lime specimen showed a strength of 30.2 pounds per square inch after the same period of curing. In the case of soil sample 2, molded at 16.$5 percent, the moisture content after the first seven days was 20.55 percent and after twenty-eight days was 21.4 percent. This during the first seven days the in­crease was 3»?0 percent, out of a total increase of 4*55 percent during the entire period of wetting. 63 64 TABLE 10 M O I3T0H2 COifTMJT OF tLM S O IL SPECIMENS AFTER CAPIL L if f '.'<IiTTL5JG "" R t t L s . Sells . 0 7 14 21 28 ...1 jS $ . . .2 1 *5. ft £ .21..8.5... ... i 21.85 2 16.8.5 .... '4.0*55 ..21.05. _ 21.40 ______2___________ ___ .. fcLuZft. PERCENT MOISTURE 65 Fig. 8 For the aoil-liiae Mature of this sati.pl© the total increase in nolsture content was 4*3 percent, Thus it is Bean that the introduction of lime hay not made any alffur-enee iii the amount of w«~tar ebsorbad. But a great differ­ence ^ pears whan the bearing value is considered. The t&'n soil Eo;oplc, aft-:;r twenty-si Jit d.yt: of soaring had became very soft, and alao developed cracks on the surface probably due to souse swelling, {Fig* $), tad Its eom-preesive strength was found to be only 3.98 pounds per square inch, Millie the apeci^ans of soll-llms mixture were quite firm without cracks on the surface (Fig,16) $ and the falue of failure stress was 169,0 pounds per square inch after twenty-eight days f curing, From this it appears that the water drawn up by the raw soil samples remained as free water in the soil epeci^an and thus gave mobility to the particles b* increasing the fchioknsss of the water film around the soil grains, while tb - water entering the soil-line mixture took part in the reaction between lime and soil and so did not prove os injurious. Considering soil sample uumber 3, molded at 19.5 percent moisture coats .t, the increase in moiature con­tent after the first seven days was to a value of 22,6 percent and aftar t.-e^ty-eight days it became 23.81 percent* During the sovran days the increase was 3.1 percent out of 66 67 Fig. 9 Raw Soil Sample After Capillary Wetting of 28 Days. Swelling in the Lower Portion ana Cracks on tiie Surface May Be Seen. Fig. 10 .ioil-Ljuae Mixture Specimens after Capillary Wetting of 28 Days. They Do Mot Shaw *-*ny Swelling or surface Crocks. a total of 4.31 percent. In the case of soil-lime mixture of this sample the total increase In moisture content after twenty-eight days of capillary absorption was 5 percent. Thus in this case the value for the soil-lime mixture is higher than that for raw soil. The raw soil specimen in this case also had developed cracks on the surface ana hau become soft, and the value for failure stress was onljf 3.9B pounds per square inch, while the soil-lime mixture after the same period was in good shape and showed s strength of 115.2 pounds per square inch. The soaking up of excess water by the soil-lime mixture can be explained by assuming that the water was needed for the reaction between lime and soil. The molded samples of sand alone were ao unstable that they gave way on handling and so no tests could be performed on the capillary absorption of sand. It is necessary to conduct tests with higher percentages of lime content in order to determine the effectiveness of lime treatment for sands. 69 Conclusions The present study has shown that soil-lime mixtures, in the case of the soils under tost, gain strength when they j.re cured, but in cur inf; they should never be subjected to wetting immediately after compaction. Wet curing should be started at least twenty-four hoars after compaction, otherwise there is danger of loosing the strength that would otherwise be achieved. The major portion of the strength is gained within the first fourteen days of curing, though it goes on increasing even afterwards. The soil-lime mixtures absorb moisture when subjected to capillary wetting, and the maximum value of absorption is reached during the first fourteen days, after that even if water is available the moisture content does not increase. It practically remains constant. Thus road beds treated with lime* after the sur­face has bean compacted ana finished, tit»y should be rested for the first twenty-four hours. fter this period they should be wet cured for fourteen days by frequent sprink­ling with water, ana no traffic should be allowed on them. It is only after fourteen days that the surface should be given soxae treatment or opened to traffic. from the study of capillary absorption, it may be concluded that when lime is mixed with these soils, the 70 water that is absorbed by these mixtures does not prove injurious as it would in the case of raw soils, and line acts as a sort of waterproof lag agent* This absorbed water probably takes part in the reaction between soil ana lime, end there is an increase in the compressive strength of these soils as the reaction between lime and soil progresses. The present study indicates that lime can be successfully used for Improving the silty soils. More detailed studies in this field will, however, be needed to generalize the conclusions. The conclusions .from the study on these soil samples are: 1) Thera is an increase in the compressive strength of the soil-lime mixtures as the molded speci­mens are cured, 2) The major portion of the strength is attained by these soil-lime mi^es within the first fourteen days of curing, 3) The soil-lime mix should not be subjected to capillary wetting immediately after molding, but should be air-cured for the first twenty-four hours. 4) No marked difference has been observed be­tween the capillary absorption of water by raw soil and soil-lime mixes. However, the water absorbed by raw soil 71 lowers its strength, that in aoil-lime helps to improve the strength. 5) *>.ost of the water in the case of raw soils is absorbed within the first eevon ways of wetting, while iii the obse of soil-lime Mixtures this period is fourteen days. Thus lixae increases the ciiae for absorption of -water by the soil mss, 6) More study with higher lirae contents is neeued in order to determine the effect!veness of lime treatment for sands, 7) The present study has shown improvement in the compressive strengths of silty soils wiien they are treated with lime, ->o far the uae of lixae has been limited to clay soils, further research in the use of lime with other types of soils is necessary to explore the foil field of its suitability as a stabilising agent* 72 APPENDIX I 74 Sample No. 1 From a trench b^twes E.H. & P.S. Building _ , University of Utah Type and Source of Material _________________ SUMMARY REPORT Screen 3" 2" l£" 1" 3/4" 3/6" $4 #10 #20 #40 #200 Screen Analysis $ Passing ,.,,1.011­. Grading Chart Gravel 0 JUG. Hygroscopic SapHlaiy Moisture _j£ Content 1.2% Binder Analysis Coarse Sand 1 Fine Sand .. 3 7 J i m _!££ ICO Classification PRAa-4 (81 Silt & Clay " ' Silt Characteristics of Material Clay Pas sing the #10 Sieve _ Capillary Rise _f______ inches QQ. n Passing the #40 Sieve ofi. Qfl Liquid Limit 22.3 P.I. Ratio 60.32 Plastic Index ?.44 P,I. Dry>©enBilsy______ f/ft. 3 Swell _ 62 /O QO.fi QQ. 3 jo 12J itet -up at Modet are Csntertfc s Jk; After' swell £/O TopJlnch Proctor Data: Optimum Moisture 13.2 Specific Gravity; 2.62______ _____ % Denstiy 113.0 i/ft.3 n ) 75 Sample No, 2 Fron Rear of \ SUMMARY REPORT Naval Rcienee Blclg Type and. Source of Material University of T)tah KC 10 * 70 4c .30 /o0 1 i gfl 3 >0 3 0 3o * Co ho ?6 U <i0 ICO s t\ \ \ \ 1 Grain Size in Millimeters 1 III Hi 1 III 1 7i i .1W l 00 50 10 1 0.i> 0.1 .05 0.01 ,0 0 b 0, 001 Gravel C.Sand F. Sand 1 Silt 1 Clay Screen Analysis Screen % Passing 3" 2 " 1" 3/4" 3/8" #4 #10 #20 #40 tf 200 100 TOT Grading Chart Gravel 0 J* W W TUTT Hygroscopic CS^a.taiy Moisture Content 1.5 6 )% Binder Analysis Coarse Sand 6. 2 Fine Sand 1 M J Classification FRAA-4 (6) Silt & Clay 79.0 75.0 2^* Characteristics of Material Clay ^7To8 Passing the #10 Sieve Capillary Rise _____ inches "9^720 Passing the #40 Sieve 93.1^ Liquid Limit 26.22 P.I, Ratio 0^« 53 Plastic Index 3.01 P.I. > R ry-D eh& ity_____ Moisture Contents SSrgJQc Proctor Data: Optimum Moisture 1?.?5 Specific Gravity: 2. 63__________ Denstiy 110.6 _#/ft.J 76 >, SUMMARY REPORT Interstate Brick Co. Sample No. 3 Type and Source of M a t e r i a l ^ It Lafr e City____ Grading Chart Hygroscopic Screen Analysis Ca^fHbSry Moisture Screen % Passing Gravel 0 % Content -■»*+ P 3" 100 Binder Analysis 2" 100 Coarse Sand 3. 20 % i £" 166 Fine Sand IK"^' % i" 100 Classification PRA A-4 (H)Silt & Clay 77. ^5 % 3 A" 100 Silt 75.50 3/8" 100 Characteristics of Material Clay .4.35. #4 #10 90..8 99.08 Passing the #10 Sieve Capillary Rise inches #20 #40 98,.71 ..95.74 Passing the #40 Sieve, ^ Liquid Limit. P.I, Ratio ?200 ..Z5.*2& Plastic Index 7 • 10 PnI. Dr*>B«SMSy S&§£L /c;o/ sm. HdmttFe 'CbMerit*; siwcef: % irofPr£nfeS Pa? Proctor Data: Optimum Moisture 1°« '5 % Denstiy 110.00 #/ft? 77 •. SUMMARY REPORT Sample Mo. 4 Type and Source of Material concrete 8ftnd Grading Chart Hygroscopic Screen Analysis C Spill's. f»y Moisture Screen % Passing Gravel % Content 0. Id % 3" 100.. Binder Analysis 2" 100 Coarse Sand 26.0 % is" 100 Fine Sand 7f.. ■: % 1" 100 Classification PRA ___________ _ Silt & Clay . o % 3/4" .1°0... Slit ___________0.1 % 3/8" Characteristics of Material 01«y j. q #4 . 1 Passing the #10 Sieve #10 93.^ Capillary Rise inchea #20 7%. 7 Passing the #40 Sieve #40 .51.1 Liquid Limit P.I. Ratio __ f200 2.9 Plastic Index _____________ P.I* ' Bryv Density_________Sw&tt________________________ % Moisture .Cofttents Set-xujx.&t______% After swell______% Ispvinch_______ % Proctor Data: Optimum Moisture 13.1 % Denstiy 112.55 #/ft? Specific Gravity: ________________ 78 SAMPLE NO, I DEGREE OF COMPACTION - A.S.H.O. STANDARD WL. OF MOLD cu. ft. DETERMINATION OF MOISTURE DENSITY RELATION FOR RA'* SOIL Trials 1 2 1 ' ? ■...... 4 5 V.et Boll - Mold Gms. 5208 5338 5^13 5392 5361 wt. of Mold Gms. 3445 3 ^ 6 3446 3446 vt. of Viet Soil G-ra?. 1?62 1892 1067 1946 1915 bet .Density Ids/ cu. ft. 106.3 124.9 129.9 128.5 126.4 1 ............ 1 Cr-n No. 1 2 3 4 5 Gsn & Vvet Soil Gras. 88.21 87.56 83.06 87.ll 86.95 C?n & Dry Poll Gras. 85.06 83. ^4 78.23 82.38 80.84 -p.ter Gms. 3.15 4.12 4.81 4.73 6.11 Can & Dry Soil G-me. 85.06 83.44 78.23 82.38 80.84 C'-;n Gins. 59. Q3 54.46 46.78 54.73 48.60 Dry Soil Gms. 25.13 2.8.98 31.^5 27.65 32.24 Moisture % Dry '■.eight 12.6 14.2 15.2 17.0 18.8 Dry Density 94.5 100.0 113.0 110.0 106.5 Frcrn Graph (pegeBl) Optimum Moisture Content = 15*2$ KaximuTn Dry Density = 113.0 lbs. tier cu.'ft. 79 SAMPLE NO. 2 DEGREE OF COMPACTION - A.A.S.H.O. STANDARD VOL. OF MOLD cu. ft. DETERMINATION OF MOISTURE DENSITY RELATION FOR RAW SOIL Trials 1 2 ' 3 r ~ 5 Wet Soil - Mold G-me. 5211 5350 5410 54o4 5364 tot. of Mold Gas. 3446 3 446 3446 3446 3446 Wt. of Wet Soil Gms. 1765 1904 1964 1958 1918 Wet Density Ibs./cu. ft. 116.5 125.8 129.7 129.3 12.6.6 Can No. 1 2 3 4 5 Can - Vet Soil Oms. 91.76 84.67 89.50 89.57 79.83 Can - Dry boll Gms. 87.80 80.85 84.54 84.10 74.35 V.ater Oms. 3.96 3.82 4.96 5.38 5 . ^ Can - Dry Soil Gms. 87.80 80.85 84.54 84.19 7^.35 Can Gms. 57.56 56.44 56.09 56.^6 48.60 Dry Soil Gms. 30.24 24.41 28.45 27.73 25.75 Moisture % Dry . wt. 13.10 15.60 17.^0 19.^0 21.30 Dry Density 103.1 109.12 L10.5 L08.0 104.35 From Graph ( page *,) Optimum Moisture Content = 17.25% Maximum Dry Density = 110.6 lbs. oer cu. ft., 80 SAMPLE NO. 3 DEGREE OP COMPACTION - A.A.S.H.O, STANDARD VOL. OF MOLD i. CH. FT, DETERMINATION OF MOIFTURE DENSITY RELATION FOR RAW SOIL Trip Is 1 1 2 3 4 5 6 Wet Boil - Mold G-mp. 5110 5317 54 01 5^23 5426 53 80 ¥t. of Mold Ome. 3446 3446 3446 3445 3446 3446 is-t. of vet foil Gms. 1664 1871 1955 1977 1980 193^ V;et Density lb?../ cu. ft. 100.9 123.6 129.1 131.6 130.7 127.8 Gan No. 1 2 3 h 5 6 Can 4 Wet Soil fee. 84.70 01.59 80.42 88.65 97.60 84.45 Can - Dr. Soil Gate. 80.43 86.79 75.^1 83.19 90.5^ 73.59 Vvster Gms. 4.27 4.80 . 5.01 5.46 7. Co 5.86 Cpr - Dry Soil Gms. 80.^3 86.79 75.^1 83.19 90.5^ 78.59 C m G"!e . 4f .60 57.77 47.56 54.65 56.09 51.73 Dry Soil GrrtF, 31.83 29.02 27.65 28.5** 3^A5 26.86 Moisture % Dry Weight 1 3.^ 16.6 18.3 19.2 20.5 21.8 Dry Density 97.10 106.0 109-U 1.10*1 108.3 105.0 From Graph ( pe-geSl) Optimum Moisture Content = 19,2.5% Maximum Pry Density - HP. 10 lbs. t>er cu. ft. DENSITY-DRY SOIL - POUNDS PER CU. FT 81 Fig, 11 aa SAMPLE WO. b (Sane) PETERM1NATION OF MOISTURE DSHSltY RELATION FOR RA* SOIL DEGBEE OF GOKPJtCflON - A.A.8.H.0* STANDARD. VOL. OF MOLD =,~ CO.Pf 30 Triple 1 ? T----- **! r....... h S 6 het P. oil - Mold 0m f?. 51<?l 5250 5327 5363 5395 \C r-4 VO fct. of Mold GMs, 3446 jiUi-6 3446 344© 3446 3446 ------- vt. of vet Coil Om e. 17l:-5 180 4 1861 1016 1949 1Q?0 V*«t Density lb?, ou. ft. 1.15.? 119.2 124.3 126.5 128.7 130.0 .. ..1 . 1 Cr.n Mo. 1 t* 4 5 6 Can - Vet Soil Gms. 112.5a 105.68 105.1 ) 87.81 1^5.9''101.76 Can - i>ry Go 11 O'fflB. 1C^.?9 it-2.26 100.9'5 83.77 10^. St > 94..34 fester Orac. 2.?3 3.42 4.11 4.08 6.11 7.42 Can - Dry Sell Grsrs. 10^.7 310?.26 100.9 3 83.77 x o h . m ► 9^.34- '. - n CNs. 61.3 ? 61.6? 64.30 51.f>7 63.^5 50.04 Gry £oil Gmp . ^B.42 ^0.39 36.69 3?..?C 41.41 44.30 •=;o3 ^t»jre > Dry "el ht .5. f h .R.47 11.2 12.5 14.74 16.75 Pry Density 100. c 110.0 111.7 112.5 112.2 111.28 Frort Graph ( page 83) . Optl*nu»n Moieture Content * 13*2# . Maxlfflttw Dry Density ** 112.55 lbs./ en. ft. DENSITY-DRY SOIL- POUNDS PER CU. FT. 83 x If.. 12 . SAMPLE NO. I DEGREE OF COMPACTION - PROCTOR VOLUME OF MOLD cu. ft, PERCENTAGE OF LIME BY WEIGHT 30 84 determination of moibture-density relations fob soil lime mix Trial 1 2 T----- f 3 4 5 vtet Mix - Mold Gme. 5068 5196 5? 78 5316 528Q Mold G-ms. 3446 3446 3446 3446 3446 ------- Vet Boil Grae. 16? 2 1750 1832 1870 1843 Viet Density lbs./ cu. ft. 107.11 115.60 121.0; 123.50 121.7C C*n Ho. 1 2 3 4 5 Can - Wet Mix Gme. 138.Q0 141.13 141.6*► 14-7.? i 138.7 1 Can - Dry Mix - Qfflg. 130.14 120.81 128.9'; 132.6 5 124.1 1 We.ter Gas. 8.82 11.32 1 .6') 14.60 14.3C Can - Dry Mix G-ms. 130.14 120.81 12.8.9'>132.65 124.4: Cc.n Gras. 59.91 54.44 5^.72 56.42 56.07 Dry Mix Gms. 70.23 75.37 7^.23 76.23 68.34 Moieture % Dry _height 11.34 15.06 17.10 19.15 20.95 Dry Density lbs./ cu. ft. 96.25 LOO.30 L03.10 103.55 qq.44 SAMPLE MO. 2 DEGREE OP COMPACTION - PROCTOR VOLUME OF MOLD - i eu. ft, PERCENTAGE OF LIME BY WEIGHT - 30 85 DETERMINATION OF MOISTURE - DENSITY RELATIONS FOR SOIL-LIME MIX TriPl 1 2 }"'■- .. *3 J 4 5 ¥et Mix - Wold Gms. 518? 5257 53^0 5361 5336 Mold Gme. 3*146 3446 244^) 3446 3446 Vvet Mix Gme, 17^1 1811 1894 1915 1890 wet Density lbs./ cu. ft. 115.00 119.6 125.1 126.4 :.24,8 Ccn No. 1 2 3 4 5 Can - Wet Mix G-ms. 132.65 66.01 130,01 1 118,7 ? 67.4g Can - Dry Mix Gros. 119,87 62.25 L15.35 103.61 62.50 we ter G-ms, 12,78 3.76 1^.73 15.16 4.99 Cen - Dry Mix Gms. L1Q.87 62.25 L15.35 103.61 62.50 Can G-ms, 41,44 4c. 32 30.75 31.37 39.5^ Dry Mix Grag. 78.43 20.93 75.6o 72.24 22,56 Moipture % Dry Weight 16.3 18.0c :L9.51 21,01 22.10 Dry Denpity VOB./ CU. ft. Q8.0 :.01.4 :-04.8 104,5 L02.10 DETERMINATION OP MOISTURE DENSITY RELATIONS FOR SOIL-LIME MIX SAMPLE NO. 3 DEGREE OF COMPACTION - PROCTOR . VOLUME OF MOLD I ' PERCENTAGE OF LIME BY WEIGHT k% 30 cu. ft. 86 . Irial 1 2 ------- 3 4 5 6 V»et Mix - Mold Gms. 5118 5186 5250 5311 5319 5283 ^°ld Gms. 3^21 3^21 3421 3421 3421 3421 Wet Mix Gms. 160? 1765 1829 1890 1898 1862 Wet Density lbs./ cu. ft. 112.0 116.5 120.8 124.8 125.3 122.9 Can No. 1 2 3 4 5 6 Cp.n - Wet Nix Gms. 123.13 125.58 122.37 138.97 135.4*> 138.32\ Can - Dry Mix Gms. 112.72- 113.28 109.7 >122.5; 118.01 118.98 fcater Gms. 10.41 12.30 12.62. 16.44 17.45 19.3^ Ccn - Dr;/ Mix Gms. L12.72 113.°8 109.75 122.53 118.01 118.98 ------- (. sn Gms. 39.92 39.72 40.83 40.30 39.66 38.68 Dry Mix Gras. 72.84 73.56 68.92 82.23 78.35 80.30 Moisture % Dry height 14.3 16.72 18.32 20.0 22.32 24.10 Dry Density lbs./ cu. ft. 97.3 ">9.8 102.00 104.00 102.6 09.0 DENSITY-DRY SOIL" POUNDS PER CUBIC FOOT 67 Fig. 13 SAMPLE NO. 4 (Sand) DEGREE OF COMPACTION - PROCTOR VOLUME OP MOLD - I 30 cu. ft. 88 DETERMINATION OF MOISTURE DENSITY RELATIONS FOR SOIL-LIME MIX Trials 1 2 r----- 3 1..... *•¥ 5 rO 'Wet Soil - Mold G-me. 523? 5-75 53?? 536$ 3417 54 02 fct. of Mold G-ms. 344-d 3*446 3446 3446 3^46 0/445 W't. of wet Soil Gme, 1?86 1829 1881 1050 2010 1956 Wet Density lbs./ cu. ft, :.18,0 120.80 124.2* 128.8 132.7 129.20 C?n No. 1 2 3 4 5 6 Cf n - Ket Soil G-itis . 83.83 87.85 104.36 104. 7f, 93.94 102.50 (Jan - Dry boll G-ms. 62.71 86.3q :.01.40 101.15 ■91.00 98.33 ¥ster Gme. 1.12 1.46 2.06 3.60 2.94 4.17 Ofin - Dry boil Gems. 82.71 86.39 ;.01.40 101.15 91.00 98.33 C?n G-ms. 5^.12 5^.95 59.80 61.37 61.87 6^.30 Dry Soil Gme. 28.59 26.44 41.60 39.78 29.13 34.03 Moisture % Dry height 3.92 5.5 7.1 9.5 11.4 12.4 Dry l)enrity lbs./ cu. ft. :.13.4 ;.14.4 '.15.8 ;-17.5 L16.3 114.8 i-ote: Graph, on page 83 APPENDIX 3T SCIL - LIME SPECIMENS MOLDED FOB. NESTING SAMPLE NO. 1 AMOUNT OF LIME BY WEIGHT Soecimen No. 1 2 3 4 .. .5 Mold - Wet Mix ftms. 5289 5253 5268 5250 5245 Mold Gms. 3--2Q 3405 34 05 3434 3405 ^et Mix Ow b . I860 18L8 1863 1816 1840 Wet Density lbp./ cu. ft. \122.8 122.03 123.0 110.90 121.5 Vi eight of Dry ! Specimen Gms. 1560 1560 1573 1550 1552 1 Can No. 1 2 3 4 5 ------ C&n - Wet Mix Gms. 72. ?Q 68.68 - 60.69 60 .45 Can - Ery Mix Qffis. 67.57 64.30 57.74 56.96 water Om s. 5.22 4.38 .2 .3 5 . .3^9 Can - Cry Mix ... Gm k , , 67*57 64. in 57.74 46.96 ------ Can G-ms. 40.?2. 4o.?6 40.34 '^8.16 Dry Mix Gme. 27.25 23.<54 - 17.^0 18.80 Moisture _ .> Dry weight IQ. 10 18.3 Same ap No, 17.00 18.52 Dry., Density .. .'las-/, an-...ft.... 10-3*0. iq,3.. a, _ > (18.; 103*3- ?) 102.3. Il22*i2 SOIL - LIME MIXTURES SAMPLE NO. 1 UNCONFINED COMPRESSION TEST DATA FOR Specimen No. Weight of Specimen as Molded Gkns. % Moisture at Molding Moisture Content Above or Be lot* Optimum Days of Curing Loaa at Failure lbs. Stress at Failure ' lbs. per sq. in. 1 I860 19. 1 - o.6 0 580 46.2 2 1848 18.3 - 0 .3 7 200 15.9 3 1863 18.3 - 0 .3 14 300 23.85 4 1816 17.0 - 1.5 21 350 27.8 5 1840 18.52 - 0.02 28 380 30.2 CAPILLARY MOISTURE DATA FOR SOIL - LIME MIXTURES SAMPLE NO. 1 Speci­men No. Wet Weight as Molded % Moisture Content at Molding Dry Weight at Molding Days of Capillarity Wei ght after Capillarity Water Absorbed i Moisture After Capillarity 1 i860 19.10 1560 0 I860 300 19.1 2 1848 18.3 1560 7 1979 419 26.8 3 1863 18.3 1573 14 1984 411 25.9 4 1816 17.00 1550 21 1932 382 24.6 5 1840 18.52 1552 28 1906 354 22.8 93 BOIL - LIME SPECIMENS MOLDED FOR TESTING SOIL - SAMPLE MO. 2 LIME - ^ BY WEIGHT Specimen No. 1 2 T--- -- 3 L$, 5 Mold - Wet Mix Grae. 53^0 5316 5303 5338 5275 Mold Gras. 3^25 3411 3425 3^25 3^11 Wet Klx Gns. 1915 1905 1878 1913 1864 Wet Density Ibe./ c u . f t . 126.43 125.83 124.03 126.3 123.06 VJeight of Dry Specimens Gns. 15 °1 157 5 1572 1588 1562 1 Can No. 1 2 3 4 5 Can - Viet Mix Gras. 108.56 71.92 94.62 90.70 82.20 Can - Dry Mix Gms. 96.99 66.43 85.85 81.81 75.63 Water Gms. 11.57 5.4Q 8.77 8.90 6.57 Can - Dry Mix Gras. 96.99 66.43 85.8 5 81.81 75.63 Csn Gms. 39.34 40.32 40.31 39.10 41.48 Dry Mix Gms. 57.65 26.11 45.54 42.?0 3^.15 Moisture $ Dry V^e i ght 20.1 21.0 19.4 20.8 19.3 Dry Density lbs./ cu. ft. L05.07 104.03 103.83 104.83 IP.2^13 SOIL - LIME MIXTURES SAMPLE NO. 2 UNCONFINED COMPRESSION TEST DATA FOR Specimen No. Weight of Specimen as Molded Gms. % Moisture at Molding Moisture Content Above or Below Optimum Days of Curing Load at Failure lbs. Stress at Failure lbs. per sq. In. 1 1915 20.1 - 0.1 0 700 55.7 2 1905 21.0 - 0.8 7 1200 Q9.5 3 1878 19.4 - 0.8 14 1700 135.5 4 1913 20.8 - 0.6 21 1975 157.5 5 1864 19.3 - 0.9 28 2125 169.0 CAPILLARY MOISTURE DATA FOR SOIL - LIME MIXTURES SAMPLE NO, 2 Speci­men No, Wet Weight P. 8 Molded P Moisture Content at Molding Dry Weight at Molding Days of Capillarity Weight after Capillarity Water Absorbed % Moisture After Capillarity 1 1915 20.1 15^1 0 1Q15 324 20.1 2 1005 21.0 1575 7 19 33 358 22.75 3 1878 19,4 1572 14 1056 384 24.4 4 1913 20.8 1588 21 1974 386 24.3 5 1864 19.3 1562 28 1939 377 24.1 SOIL - LIME SPECIMENS MOLDED FOE TEFTING SOIL - SAMPLE NO. 3 LIME - BY WEIGH? Specimen No, 1 2 T .. ' ' 4 5 Mold - Wet Mix G-ms. 5306 53?2 5310 5322 5306 Kold (Ms. r-! -■? Or\ 3^15 3^15 3^15 3415 Wet Mix G-ras. 18<?1 1907 1695 1907 1891 feet Density lbf. / cu. ft. 124.8? 125.96 125.r 1125.96 124.8' 1 Weight of Dry SDeclmen G-ms. 1575 1580 1570 1576 1571 Can No, 1 2 3 4 5 Can - Tset Mix Gap. 67.50 70.47 7^.29 73.05 74.32 G*n - Dry Mix G-ma. 62.82 73.05 68.77 0 7 .O8 08.86 water Gras. 4.68 6.4-2 5.52 5.97 5.46 Can - Dry Mix Gins. 62.82 73.05 68.77 67.08 68.86 Can &ms. 39.08 42.34 4-2,2? 38.6? 42.23 Dry Mix G-ms. 2 3 ,1.4 30.71 26.51 28.41 26.63 Moisture % 'Dry Weight 20.25 20.90 20.80 21.00 20.4- Dry Density 103.80 .104-. 3 103.7 O ■h'w • O 103.77 SOIL - LIME MIXTURES SAMPLE NO. 3 UNCONFINED COMPRESSION TEST DATA FOR Specime n No. Weight of Specimen as Molded Gms. % Moisture at Molding Moisture Content Above or Below Optimum Days of Curing Load at Failure lbs. Stress at Failure lbs. per sq. in. 1 1891 20.25 - 0.75 0 410 32.6 2 1907 20.90 - 0.10 7 1000 79.5 3 1895 20.80 - 0.20 14 1200 99.5 4 190? 21.00 0.0 21 1350 107.5 5 1891 20.4 - 0.6 28 1450 115.2 CAPILLARY MOISTURE DATA FOR SOIL - LIME MIXTURES SAMPLE NO. 3 Speci­men No. Wet Weight as Molded Gkas. % Moisture Content at Welding Dry Weight at Molding Days of Capillarity height after Capillarity Water Absorbed % Moisture After Cspillarity I 1891 ■<<*5c iv**« <% r" . 0 1575 0 1891 316 20.25 2 190? 20.90 1580 7 1955 375 23.7 3 1895 20.80 1570 14 1Q57 387 24.8 4 1907 21.00 1576 21 1067 391 24.8 5 1891 20.4 1571 28 1964 393 25.0 99 SOIL-LIME SPECIMENS MOLDED FOR TESTING SOIL-SAMPLE NO. 4 LIFE - BY WEIGHT !Boecire~n Ko. 1 2 V' - .- " 3 *4 . 5 Mold - Wet Mix Gms. 53^0 5365 53^5 5329 5335 Mold Gns. 3^25 3^25 3^25 3^11 3^25 ------------------ Wet Mix Orne. 1035 1940 1920 1918 1910 l>et Density 11)%./ on. ft. 127.83 X ^ 0 n 126.8 126.63 126.1 Weight of D r y Specimen One. 1772 1772 1755 1756 17^5 -r ! C a n N o . 1 2 4 5 C a n - W e t M i x G n s . 7 2 . 0 4 7 3 . 1 9 7 3 . 6 2 9 3 . 0 1 9 6 . 7 1 C a n - D r y M i x G r a s . S o . 2 5 7 0 . 2 1 7 0 . 6 0 8 8 5 0 5 9 1 . 7 0 ¥ s t e r S m s . 2 . 7 9 2 . 9 8 2 . 9 3 ^ . 5 0 5 5 . 0 1 C a n - D r y M i x G m s . 6 9 . 2 5 7 0 . 2 1 7 0 . 6 9 P 6 . 5 C 5 c l . 7 0 ------------ C a n G m s . 3 8 . 6 4 3 8 . 6 6 3 9 . 2 0 3°.12 3 9 . 0 7 D r y M i x G t t ] 8 . 30.61 3 1 . 5 5 3 1 . ^ 9 ^ 9 . 3 8 5 5 2 . 6 3 M o i s t u r e % D r y W e i g h t 9 . 1 2 . 9 . 4 6 9 . 3 0 9 . 1 5 9 . 5 3 D r y D e n s i t y l b s . / c u . f t . 1 1 7 . 0 3 3 1 7 . 0 3 1 1 5 . 9 3 m . o 3 5 5 . ' - 3 SOIL - LIME MIXTURES SAMPLE NO. 4 UNCONFINED COMPRESSION TEST DATA FOR Specimen No. Weight of Specimen as Molded. Gms. % Moisture at Molding Moisture Above or Below Optimum Days of Curing Load at Failure lbs. Stress at Failure lbs. sq. in. 1 1935 9.12 - 0.63 0 250 19.88 2 1940 9.46 - 0.29 7 175 13.90 3 1920 9.30 - 0.45 14 50 3.98 4 1910 9.53 - 0.22 28 50 3.98 5 1918 0.15 - 0.6c 21 50 3.98 CAPILLARY MOISTURE DATA FOR SOIL - LIME MIXTURES SAMPLE NO. 4 Speci­men No. Viet Weight aa Molded Gras. % Moisture Content at Molding Dry Weight at Molding Days Weight of After Capillarity Caoillarity Water Absorbed % Moisture After Capillarity 1 1935 9.12 1772 0 1935 163 9.12 2 1940 9.46 1772 7 1927 155 8.75 3 1920 9.30 1755 14 1059 204 11.8 4 191o 9.53 1745 28 1951 206 11.8 5 1Q18 9.15 1756 21 1925 169 9.64 RAW SOIL SPECIMENS MOLDED FOR CAPILLARY WETTING SOIL SAMPLES 1, 2, 3, 4 Sell Staple 2 ■ n i . 3 4 Mold - Wet Soil Gme. 5398 53?8 5364 5327 Mold Gms, 34 Z? 3^27 3 ^ 2 7 3427 Wet Boil &?T(8 . 1971 19 51 1Q3? 1Q00 Wet Density IDs./ cu. f&. 130. Vt 126,8? 126.4: 325.50 Soil Bample 1 3 4 Can - Wet Soil Gms. 96.41 Q5.64 88.26 7°. 36 Can - Dry Soil Gms. 88.55 87.49 80.2? 74.97 We ter Gm g. 7.86 8.15 7."39 4.39 Can - Dry Boil . Gms. BQm 55 87. 49 80.27 74.97 C8-n o™. 3°. 68 39.10 39.22 39.09 Dry Mix Gme. 48.87 48.30 41.05 35.88 ^"StfPseight 16.10 16.85 19.50 12.22 Dry Density lbs?./ cu. ft, 112 J2 110.3 1C?. 50 321.80 CAPILLARY MOISTURE DATA FOR RAW - SOIL SAMPLE NO. 1 Specimen No. Vet Weight as Molded G-ms. % Moisture Content at Molding Dry Weight at Molding G-ms. Days Weight of After Capillarity Capillarity (5ms. Water Absorbed Sms. % Moisture After Capillarity 1 1971 16.1 1698 0 1971 273 16.1 2 7 2063 365 21.5 3 14 2068 370 21.8 4 21 206q 371 21.85 5 28 2069 371 21.85 Compressive Strength after 28 days ~ 75 lbs. (Uneonfined test) = 5.97 lbs. per sq. in. CAPILLARY MOISTURE DATA FOR RAW - SOIL SAMPLE NO. 2 Speci­men No. Wet % Moisture height Content at as Molding Molded Oms. Dry weight at Molding Stas. Days of Capillarity Weight After Capillarity Water Absorbed % Moisture After Capillarity 1 1951 16.85 16?0 0 1951 281 16.85 2 7 2013 343 20.55 3 14 2022 352 21.05 4 21 2026 356 21.30 5 28 2028 358 21.40 Compressive Strength after 28 clays = 50 lbs. (Unconfihed Test) , 3-98 lbB. p(sr. sq, ln- CAPILLARY MOISTURE DATA FOR RAW SOIL SAMPLE NO. 3 Speci­men No. Wet Weight as Molded G-ms. % Moisture Content at Molding Dry Weight at Molding Gme. Days of Capillarity Weight After Capillarity Grns. Water Absorbed G-ras. % Moisture After Capillarity 1 1937 19.5 1620 0 1937 317 19.5 2 7 1Q87 36? 22.65 3 14 1997 377 23.45 4 21 2004 384 23.70 5 28 2006 386 23.81 Compressive Strength after 28 days - 50 lbs. (Unconfined Test) _ = 3.98 lbe. per sq. in. APPENDIX nr THE COMPACTION AND DENSITY OF SOIL (A.A.S.H.O. Designation; T 90-38) Scope. 1. The standard, density test for soil determines the weights per cubic foot under a standard compaction for varying water contents of such a range as to show the maximum dry weight per cubic foot. N - Apparatus 2. The apparatus shall consist of the following: (a) Mold.- A cylindrical metal mold approximately 4 in. in diameter and ^.6 in. in height and having a volume of 1/30 cubic foot. This mold is fitted with a detachable base plate and a removable extension approximately 2.5 in. in height. (See figure page ). (b) Rammer,- A metal rammer having a 2 in. diameter cir­cular face and weighing 5.5 pounds. The rammer shall De equipped with a suitable arrangement to control the specific drop. (c) Sleeve.- Closed cylindrical sleeve slightly less than 4.0 inches in diameter or similar device for removing compacted specimens from mold. (d) Balances.- A balance or scale of 25 pound capacity sensitive to 0.01 pound; and a lOOg. capacity balance sensitive to O.lg. 107 if (e) Drying Oven.- A thermostatically controlled drying oven capable of maintaining temperatures of about 110° C. (230° F) for drying moisture samples. (f) Straightedge.- A steel straightedge 12 inches long. Procedure 3. (a) A 3000 g. (aooroximetely 6-oound) sample, air-dried to slightly damp, shall be taken from a portion of the materiel pa se in or the No. 4 sieve obtained In accordance with the Standard Method of Preparing Disturbed Soil Samples for Test (A.A.S.H.Q. Designation; T 8?}. (b) The sample shall he thoroughly mixed, then compacted in the cylinder (with the extension attached.) in three equal layers, each layer receiving 25 blows from the tamper drooped from a height of 1 foot above the soil. The extension shall then be removed. The compacted soil shall be carefully leveled off to the top of the cylinder with straightedge and weighed. (c) Th~ i,:;ht of the compacted sample and cylinder, minus the weight of the cylinder, shall then be multiplied by 30 and the re suit recorded as the wet weight per cubic foot of the compacted soil. (d) The compacted mass of the soil shall be removed from the cylinder and sliced vertically through its center. A 100-g. sample taken from the center of the mass shall be weighed im­mediately and dried in an oven at 110 c (230 F) to determine the moisture content. ' 1C 3 (e) The remeindtr of the mat*riel shs.ll be broken up until it will punc a No, k sieve, Vater in sufficient amounts to in* crease the moisture content of the poll sample by approximately 1 per cent shall be added and the above procedure repeated for each increment of vater added. This series of determinations shall be continued until the soil beeo^es very wet and there is a substantial dtercfi.ee in the vet weight of the compacted eoil. C?-lcnl-- tl one 4. The moisture content and the dry weight of th* soil ae compacted shell be eeleuleted by means of the following formulas Moisture, per cent - ".*' ......... 100 B - C Dry weight per cu. ft. of compacted soil - wet weight, lb. pgr cu. ft. X 100 per cent moisture - 100 where A le weight of dish end wet soil B is weight of dish find dry soil C is weight of dish. Moisture Density Relationship 5. The results of the connection tests, corrected for weight of moisture and expressed as pounds of dry soil per cubic foot, are slotted against their respective moisture contents snd a smooth curve drewn through the resulting points. The peak of the curve represents the maximum density for the given material '10 under the above compaction, <md the percentage of vr ter at this point represents the moisture content necessary td give the maxi mum c ompa c 11 o n. ) U DENSITY CY L INDER Figure 14 APP2HD1X W 113 A.PPIR*TTT? FOR CAPILLARY GETTING . o f bfh:c i m sns To subject the soil-lime specimens to capillary wetting during the curing period the apparatus shown on the next page was assembled. The problem was to wet the specimens in such a way that they were not in direct contact with free water but they could dravr it by capillarity. For this & wooden frame 20M X 2*4" in size was mace with 1 ^ X 3/4" wooden pieces, and top face of this frame was fitted with window screening. Under the screening the frame was packed with waste cotton, while over the screen a oad of absorbent cotton between two sheets of blotting papers was placed. This frame was then placed in a tray, which was filled with water sufficient to reach the level of the window screening in the frame. The specimens were placed over the blotting paper. The whole set up was placed in the moist cabinet, whose temperature was maintained at 65° to 70° F. The water level in the tray was checked from time to time and more water was added when it fell below the level of the screen. 114 APPARATUS FOR ' CAPI LLARY WETTI NG 5CALE I'* I FT. PLi\N E L E .V A T IO N Abswt<»nt Cotlofl Wakr . ± .SECTION AT A A fl/ofttng Paper _w»ndo*> Screening Waste Cotton F.gT 15 APPENDIX V 1 1 6 RSFB.mC.BS BOOKS Eogentogler, C. A., Engineering Properties of .Soils. Hew York: McGraw-Hill Bools Company, 1937. Sloane, R. L. Laboratory manual of Testing Procedures for Soils. Salt Lake City: Department of Civil Engineering, University of Utah, 1949. JOURNALS Dockery W. D. and Manigault D. 3. H. "Lime Stabili­zation and Low Cost Roads Construction", Roads and Streets Magazine. Vol. XC, (1947) pp. 91-95. Freeborough B. B, "Lime Treatment Permits Use of Substandard Flexible Base Materials", Public Works Magazine, June 1947. G-olabeck A. T. "Researches on the Structural Design of 1 ighway by the U.S. Bureau of Public Roads", Trans. A. S. G. S.. Vol. XXCVIII, 1925, pp. 266­300. Hogentogler C. A, and S. A. '*17 ill is, "Stabilized Soil Roads", Public Roads i-a azine. Vol. XVII, 193-6, pp. 45-64. Lesesne, Sherman D., "Stabilization of Clay Roadbed with Lime", Pamphlet published by National Lime Association, 1940. Li, Lo Chih, "Research on Soil Stabilization^, Pro­ceedings highway Research . oard. Vol. XXIII, 1940, p. 413. Lime Used in Airfield Base, Roads and Streets Lagazine, Vol. XCI, 1948, pp. 96. i.icCaustland J. "Lime in Dirt Roads", Proceedings Hational Lime Association Convention, May, 1925. ii.7 iicDo'well, Chester, "The lisa of Hydrated Lime for Stabilizing Roadway Materials", Paper read at National Lime association Convention, April, 1948. McDowell, Chester, ''Progress Report on Development . and Use of Strength Tests for Subgrades Soils and Flexible Base Materials", Proceedings llipdi-way Research Board. Vol. XXVI, 194b, p. 484. "Roads of Antiquity", isaerlcan Public Hlrdiways. August, 1945. "Report of Soil Stabilization Committee" Presented at the 45th Annual Convention and Road Show American Road Builders Association, July, 1948. Woods Jr., H. W», "Lime in iiarth Roads", Proceedings National Lime Association Convention, June, 1926, P. 57.