Form DOT F ) FHWA/TX-79/ THE EFFECTS OF SOIL BINDER AND MOISTURE ON BlACKBASE MIXTURES. Wei-Chou V. Ping and Thomas W.

Transcription

1 TCHNICAL RPORT STANDARD TITL PAG 1. Report No. 2. Government Aession No. FHWA/TX79/ Title and Subtitle TH FFCTS OF SOIL BINDR AND MOISTUR ON BlACKBAS MIXTURS 7. Author!.) WeiChou V. Ping and Thomas W. Kennedy 3. Reipient's Catalog No. 5. Report Date May Performing O'ganization Code 8. Performing Organization Report No. Researh Report Performing Organi zation Name and Addre Center for Highway Researh The University of Texas at Austin Austin, Texas Sponsoring Ageny Name and Address Texas State Department of Highways and Publi Transportation; Transportation Planning Division P. O. Box 551 Austin, Texas Supplementary Note. 1. Work Un" No. 11. Contrat or Grant No. Researh Study Type of Report and Period Covered Interim 14. 5ponsoring Ageny Code Study ondu ted in oopera tion wi th the U. S. Department of Transporta tion, Federal Highway Administration. Researh Study Title: 1tTensile Charaterization of Highwav Pavement Materials" 16. Ab'trat This report desribes a study whih was undertaken to evaluate the effet of the amount of soil binder on the engineering properties of asphalttreated paving materials. For this study soil binder was onsidered to be aggregate finer than U. S. standard sieve size No. 4. The stati and repeatedload indiret tensile tests were used to measure engineering properties of asphalt mixtures for purposes of mixture design and evaluation. Two aggregates, a rounded gravel and a rushed limestone, eah with various soil binder ontents, were mixed with a range of asphalt ontents to produe test speimens. The engineering properties were ompared for the various soil binder ontents. Results of these omparisons indiated that the various engineering properties ould be maximized at relatively low soil binder ontents and at lower asphalt ontents. 17. Key Word. blakbase, asphalt onrete, asphalttreated, soil binder ontent, indiret tensile test, tensile strength, modulus of elastiity, fatigue life, permanent deformation, engineering properties 18. Oi stribution Stotement No restritions. This doument is available to the publi through the National Tehnial Information Servie, Springfield, Virginia Seurity Clauil. (of this report) 2. Seurity ClouH. (of this page) 21. No. 1 Pages 22. Prie Unlassified Unlassified 127 Form DOT F )

2 TH FFCTS OF SOIL BINDR AND MOISTUR ON BLACKBAS MIXTURS by WeiChou V. Ping Thomas W. Kennedy Researh Report Number Tensile Charaterization of Highway Pavement Materials Researh Projet onduted for Texas State Department of Highways and Publi Transportation in ooperation with the U. S. Department of Transportation Federal Highway Administration by the CNTR FOR HIGHWAY RSARCH TH UNIVRSITY OF TXAS AT AUSTIN May 1979

3 The ontents of this report reflet the views of the authors, who are responsible for the fats and the auray of the data presented herein. The ontents do not neessarily reflet the offiial views or poliies of the Federal Highway Administration. This report does not onstitute a standard, speifiation, or regulation. ii

4 PRFAC This is the twelfth in a series of reports dealing with the findings of a researh projet onerned with tensile and elasti harateristis of highway pavement materials. This report summarizes the results of a limited study to evaluate the effet of soil binder ontent on the behavior of blakbase mixtures used in Texas. The evaluation was based upon the results obtained using the stati and repeatedload indiret tensile tests on two blakbase mixtures whih have been used in Texas. This report was ompleted with the assistane of many people. Speial appreiation is due James N. Anagnos and Pat Hardeman for their assistane with the testing program and Frank. Herbert, Gerald Pek, and Robert. Long of the Texas State Department of Highways and Publi Transportation, who provided tehnial liason and support for the projet. Appreiation is also extended to personnel from Distrits 5 and 13 who assisted in obtaining the blaekbase materials used on the projet and to the Center for Highway Researh staff who assisted in the preparation of the manusript. The support of the Federal Highway Administration, Department of Transportation, is aknowledged. Wei Chou V. Ping Thomas W. Kennedy May 1979 iii

5 LIST OF RPORTS Report No. 1831, "Tensile and lasti Charateristis of Pavement Materials," by Bryant P. Marshall and Thomas W. Kennedy, summarizes the results of a study on the magnitude of the tensile and elasti properties of highway pavement materials and the variations assoiated with these properties whih might be expeted in an atual roadway. Report No. 1832, "Fatigue and RepeatedLoad lasti Charateristis of Inservie AsphaltTreated Materials," by Domingo Navarro and Thomas W. Kennedy, summarizes the results of a study on the fatigue response of highway pavement materials and the variation in fatigue life that might be expeted in an atual roadway. Report No. 1833, "Cumulative Damage of Asphalt Materials Under RepeatedLoad Indiret Tension," by Calvin. Cowher and Thomas W. Kennedy, sunnnarizes the results of study on the appliability of a linear damage rule, Miner's Hypothesis, to fatigue data obtained utilizing the repeatedload indiret tensile test. Report No. 1834, "Comparison of Fatigue Test Methods for Asphalt Materials," by Bryon W. Porter and Thomas W. Kennedy, summarizes the results of a study omparing fatigue results of the repeatedload indiret tensile test with the results from other onnnonly used tests and a study omparing reep and fatigue deformations. Report No. 1835, "Fatigue and Resilient Charateristis of Asphalt Mixtures by RepeatedLoad Indiret Tensile Test," by Adedare S. Adedimila and Thomas W. Kennedy, summarizes the results of a study on the fatigue behavior and the effets of repeated tensile stresses on the resilient harateristis of asphalt mixtures utilizing the repeatedload indiret tensile test. Report No. 1836, "valuation of the Resilient lasti Charateristis of Asphalt Mixtures Using the Indiret Tensile Test," by Guillermo Gonzalez, Thomas W. Kennedy, and James N. Anagnos, sunnnarizes the results of a study to evaluate possible test methods for obtaining elasti properties of pavement materials, to reommend a test method and preliminary proedure, and to evaluate properties in terms of mixture design. Report No. 1837, "Permanent Deformation Charateristis of Asphalt Mixtures by RepeatedLoad Indiret Tensile Test," by Joaquin Vallejo, Thomas W. Kennedy, and Ralph Haas, summarizes the results of a preliminary study whih ompared and evaluated permanent strain harateristis of asphalt mixtures using the repeatedload indiret tensile test. iv

6 Report No. 1838, "Resilient and Fatigue Charateristis of Asphalt Mixtures Proessed by the DryerDrum Mixer," by Manuel Rodriguez and Thomas W. Kennedy, summarizes the results of a study to evaluate the engineering properties of asphalt mixtures produed using a dryerdrum plant. Report No. 1839, "Fatigue and RepeatedLoad lasti Charateristis of Inservie Portland Cement Conrete," by John A. Crumley and Thomas W. Kennedy, summarizes the results of an investigation of the resilient elasti and fatigue behavior of inservie onrete from pavements in Texas. Report No. 1831, "Development of a Mixture Design Proedure for Reyled Asphalt Mixtures," by Ignaio Perez, Thomas W. Kennedy, and Adedare S. Adedimila, summarizes the results of a study to evaluate the fatigue and elasti harateristis of reyled asphalt materials and to develop a preliminary mixture design proedure. Report No , "An valuation of the Texas Blakbase Mix Design Proedure Using the Indiret Tensile Test," by David B. Peters and Thomas W. Kennedy, summarizes the results of a study evaluating the elasti and repeatedload properties of blakbase mixes determined from urrent blakbase design proedures using the indiret tensile test. Report No , "The ffets of Soil Binder and Moisture on Blakbase Mixtures," by WeiChou V. Ping and Thomas W. Kennedy, summarizes the results of a study to evaluate the effet of soil binder ontent on the engineering properties of blakbase paving mixtures. v

7 ABSTRACT This report desribes a study whih was undertaken to evaluate the effet of the amount of soil binder on the engineering properties of asphalttreated paving materials. For this study soil binder was onsidered to be aggregate finer than U. S. standard sieve size No. 4. The stati and repeatedload indiret tensile tests were used to measure engineering properties of asphalt mixtures for purposes of mixture design and evaluation. Two aggregates, a rounded gravel and a rushed limestone, eah with various soil binder ontents, were mixed with a range of asphalt ontents to produe test speimens. The engineering properties were ompared for the various soil binder ontents. Results of these omparisons indiated that the various engineering properties ould be maximized at relatively low soil binder ontents and at lower asphalt ontents. KY WORDS: blakbase, asphalt onrete, asphalttreated, asphalt stabilized, soil binder ontent, mixture design, indiret tensile test, engineering properties, tensile strength, modulus of elastiity, resilient modulus, fatigue life, permanent deformation. vi

8 SUMMARY The purpose of this study was to evaluate the effets of soil binder ontent on the behavior of blakbase mixtures used in Texas. For this study soil binder was onsidered to be aggregate finer than U. S. standard sieve size No. 4. The evaluation was based upon a omparison and analysis of engineering properties obtained using the stati and repeatedload indiret tensile tests on mixtures with various soil binder ontents. For this study two blakbase mixtures, a rounded gravel and field sand and a rushed limestone. ah of these aggregates has been used in a blakbase mixtures. Various engineering properties were evaluated at various soil binder ontents and asphalt ontents. The engineering properties evaluated were tensile strength, stati modulus of elastiity, fatigue life, resilient modulus of elastiity, and resistane to permanent deformation. All tests were performed at 24 C (75 F). Most of the tests were onduted on speimens whih were air dried; however, a limited number of tests were onduted on pressure wetted speimens to evaluate the influene of moisture ontent. Generally, the results indiate that the various engineering properties were maximized at relatively low soil binder ontents and at orrespondingly lower asphalt ontents. The optimum asphalt ontents tended to derease as the soil binder ontent dereased. The optimum soil binder ontents for the various engineering properties ranged from 5 to 1 perent. In addition, the lowest optimum asphalt ontents ourred at soil binder ontents of 5 and 1 perent. vii

9 IMPLMNTATION STATMNT Based on the findings of this study, it is reommended that additional onsideration be given to the effets of soil binder ontent. The results of a limited amount of testing indiated that relative low binder ontents maximize various engineering properties and minimize the optimum asphalt ontents. Both effets suggest that lower binder ontents are desirable; however, additional study is needed before final reommendations are made. viii

10 TABL OF CONTNTS PRFAC LIST OF RPORTS ABSTRACT SUMMARY. IMPLMNTATION STATMNT iii iv vi vii viii CHAPTR 1. INTRODUCTION 1 CHAPTR 2. XPRIMNTAL PROGRAM 2 Materials agle Lake Material Lubbok Material Aggregate Gradations.. Speimen Preparation.. Testing quipment and Proedures Properties Tensile Strength..... Stati Poisson's Ratio Stati Modulus of lastiity Fatigue Life Resilient Poisson's Ratio.. Resilient Modulus of lastiity AsphaltVoids Ratio Density Total Air Voids... Permanent Deformation Testing Program CHAPTR 3. ANALYSIS AND DISCUSSION OF TST RSULTS AVR Design Optimum Asphalt Content agle Lake Gravel Lubbok Limestone.. Density Stati Indiret Tensile Test Results Tensile Strength Stati Modulus of lastiity RepeatedLoad Indiret Tensile Test Results Fatigue Life ix

11 Resilient Modulus of lastiity Permanent Deformation Moisture Damage CHAPTR 4. CONCLUSIONS AND RCOMMNDATIONS Conlusions General Stati Charateristis RepeatedLoad Charateristis Moisture Damage Optimum Asphalt Content.. Optimum Soil Binder Content Reommendations RFRNCS 84 APPNDICS Appendix A. Appendix B. Appendix C. Appendix D. Mixture Gradations Preparation of Sample for Moisture Damage Summary of Stati Test Charateristis Summary of Repeated Load Charateristis x

12 CHAPTR 1. INTRODUCTION The primary objetive of this investigation was to evaluate the effet of soil binder ontent on the behavior and design of blakbase paving mixtures used in Texas. Soil binder is material whih will pass the U. S. standard No. 4 sieve as defined by the Texas State Department of Highways and Publi Transportation. In pratie, the aeptability of an aggregate gradation for use in asphalt mixtures is usually judged by its onformity to speified partiular size limits (Ref 9). These limits have generally been established either on the basis of satisfatory experiene with materials whih meet seleted gradation speifiations or in terms of seleted gradation patterns of natural or rushed material that are readily available. Thus, it is possible to have gradation limits whih vary signifiantly but whih will still produe satisfatory asphalt mixtures (Ref 14). In Texas, a range of binder ontents is speified as a part of the gradation requirements (Ref 27). However, the Texas Department of Highways and Publi Transportation raised the question as to the effet of binder ontent and whether improved, or less ostly, mixtures an be produed by speifying a limited binder ontent or by eliminating all speifiation requirements onerning binder ontent. To answer these questions, the Department of Highways and Transportation requested that a limited study be onduted to determine the effet of soil binder ontent on asphalt paving mixtures. Previous investigations in Researh Study , "Tensile Charaterization of Highway Pavement Materials," suessfully utilized the stati and the repeatedload indiret tensile tests to measure engineering properties of asphalt mixtures for purposes of mixture design and evaluation. These tests were used, therefore, in this study to measure properties related to the distress modes of thermal or shrinkage raking, fatigue raking, and rutting. The experimental program is desribed in Chapter 2. Test results and findings are presented and disussed in Chapter 3, and the onlusions and reommendations are ontained in Chapter 4. 1

13 CHAPTR 2. XPRIMNTAL PROGRAM The purpose of this investigation was to evaluate the effet of the amount of soil binder on the engineering properties of asphalttreated paving materials. For this study, soil binder was onsidered to be aggregate finer than U. S. standard sieve size No. 4. The basi experimental approah was to ompare the engineering properties of asphalt mixtures omposed of two representative types of aggregate, eah with various soil binder ontents. The two aggregates were a rounded river gravel and a rushed limestone (alihe), both of whih are ommonly used in pavement onstrution in Texas. By hanging the quantity of soil binder, eah seleted aggregate gradation was mixed to produe laboratory speimens with asphalt ontents in the range generally used for design. This hapter desribes the materials, aggregate gradations, equipment, and proedures used in the investigations. MATRIALS The two aggregates used in this investigation were obtained from agle Lake and Lubbok, Texas. ah of these aggregates has performed satisfatorily in pavements and has been studied in a previous investigation (Ref 24). agle Lake Material The agle Lake material was a mixture of four different aggregates; Lone Star oarse aggregate, Lone Star Gem sand, Tanner Walker sand, and Stiles oarse sand. The Lone Star Gem sand and Lone Star oarse aggregate are silieous river gravels with rushed faes. Tanner Walker sand and Stiles oarse sand are field sands. The ombined aggregates an be generally desribed as smoothsurfae, angular, nonporous, rushed river gravel. This ombination of aggregates was used in the b1akbase onstrution of SH 71 south of Columbus, Texas. 2

14 3 The asphalt ement was an AC2, produed at the xxon refinery in Baytown, Texas and supplied by Distrit 13 of the State Department of Highways and Publi Transportation (DHT). The asphalt properties, as determined by the DHT, are summarized in Table 1. Lubbok Material The Lubbok material was a rough, subangular, porous, alihe type rushed limestone obtained from Long Pit, loated approximately ten miles southeast of Lubbok, Texas. This aggregate was used for the blakbase onstrution of 127 between the north loop of Lubbok and New Deal, Texas. The asphalt ement was an ACIO produed by the Cosden Oil Refinery in Big Spring, Texas. The asphalt properties as determined by the DHT are summarized in Table 1. AGGRGAT GRADATIONS The gradation of the agle Lake gravel used for the onstrution of SH 71 and the gradation of the Lubbok limestone used for the onstrution of 127 were used as basi gradations, one for eah material. The agle Lake field gradation was a mixture of the four different aggregates in the following proportions: Aggregate Lone Star oarse aggregate Tanner Walker sand Lone Star gem sand Stiles oarse sand Perent The field gradation ontained 3 perent soil binder. For agle Lake gravel, the soil binder ontents seleted for study were 3, 2, 1, 5, and perent. Gradations of the resulting mixtures are shown in Fig 1 and are listed in Table 2. The detailed individual aggregate gradations are ontained in Appendix A. For Lubbok limestone, the field gradation had 25 perent soil binder. The soil binder ontents seleted for study were 25, 1, 5, and perent.

15 TABL 1. SUMMARY OF ASPHALT CMNT PROPRTIS* agle Lake Gravel Lubbok Limestone Asphalt type AC2 AC1 Produer xxon Cosden Oil Water, perent nil nil Visosity at 135 C (275 p), stokes Visosity at 6 C (14 F), stokes 2, Solubility in CC1 4, perent >99.7 >99.7 Flash point, C.O.C.,, (OF) >315 (6) >315 (6) Dutility at 25 C (77 F), 5 m/min, m Penetration at 25 C (77 F), 1 g, 5 se Speifi gravity at 25 C (77 F) Tests on residues from thin film oven test: Visosity at 6 C (14 F), stokes 3,574 2,172 Dutility at 25 C (77 P), 5 em/min, m >141 >141 Spot test neg neg *As reported by the State Department of Highways and Publi Transportation

16 Sieve S izes U.S. Standard o CD CD CD... O N N rt) an,... I 11 I 1 I 91 I hh I r I Ri'Yi '+11 3 at : :." en C Soil 1 SO Binderr+5 : : P" J =r : / J! jy."""':... / lao 1 1 :::ol1/ A :;;>/...= 19 o I C5F7S If i I I[ II 1 1 an. an an o an Partile Size Diameter in mm 3 / Finer Than No.4 Sieve (Basi Field Gradation) 2 / Finer Than No.4 Sieve S lo Finer Than No.4 Sieve l:::t: 1 / Finer Than No.4 Sieve / Finer Than No.4 Sieve "C Fig 1. Gradations of agle Lake gravel mixtures. V1

17 TABL 2. GRADATIONS OF MIXTURS U.S. Standard Sieve Size, Cumulative % Retained Material % of Desrip Soil tion Binder 1 1/4" 1" 7/8" 5/8" 1/2" 3/8" 114 filo #2 # agle Lake gravel Lubbok limestone Q'\

18 7 Gradations of the resulting mixtures are shown in Fig 2 and are listed in Table 2. The various gradations and perent soil binders were obtained by adding or removing material finer than the No. 4 sieve while maintaining a onstant amount of the oarser material. SPCIMN PRPARATION All speimens prepared for this investigation were mixed and ompated aording to Test Method Tex126 exept that the mixing was done using an llliter (12quart) apaity Hobart mixer rather than by hand mixing (Ref 17). The omplete mixing and ompation proedures are summarized below. The aggregates were bathed by dry weight, mixed with asphalt ement at 177 C (35 F), and ompated at 127 C (26 F). Compation was performed using the Texas GyratoryShear ompator. The maximum ompressive stress, 345 kpa (5 psi), was applied to the speimen after gyration. This stress was maintained until the vertial deformation rate was less than.5 in. per 5minute period, at whih time the inmold density, or AVR (AsphaltVoids Ratio) density, was determined. The resulting speimen was approximately 152 mm (6 in.) in diameter and 2 mm (8 in.) high. All speimens were allowed to ool in the ompation mold for about one hour before extrusion to prevent slumping of the speimen. This was neessary beause a uniform diameter is desirable so that the loading strips used for indiret tensile testing will be in omplete ontat with the speimen. After extrusion from the mold, the speimens were allowed to ure overnight at room temperature. Smaller test speimens for the indiret tensile test were then ut from the top and bottom portions of the ompated speimen. The densities of these test speimens were alulated from their weights and physial dimensions. The top and bottom speimens were ured overnight at a room temperature of approximately 24 C (75 F). Thus, the total uring time was two days. The sawed indiret tensile test speimens were generally 152 rnm (6 in.) in diameter and about 84 mm (3.3 in.) in height. To evaluate the effets of moisture, the exposed sawed faes of the test speimens were oated with a thin film of the same asphalt ement used in the mixture. Then the speimens were subjeted to pressure wetting (Test Method

19 CJ' Sieve Sizes U.S. Standard N : : II) 6 4 II) Q.. Soil 5 5 a: : : Binder u ' 4 6 u ' Q " 7 Q.. 1 If) If) If) If) Partile SizeDiameter in mm 25 / Finer Than No.4 Sieve (Basi Field Gradation) 5 1o Finer Tha n No.4 Sieve 61 / Finer Than No.4 Sieve / Fi ner Tha n No.4 Sieve Fig 2. Gradations of Lubbok limestone mixtures.

20 9 Texl9, Part IV). This proedure subjets a speimen to an 8274 kpa (12 psi) hydrostati water pressure at a water temperature of 65 C (15 F) for 15 minutes prior to atual testing using the indiret tensile test. The detailed proedure is desribed in Appendix B. TSTING QUIPMNT AND PROCDURS The testing equipment for the stati and repeatedload indiret tensile tests was the same as that used in previous studies onduted at the Center for Highway Researh. The basi testing apparatus was an MTS losedloop eletrohydrauli loading system. A preload of 9 N (2 lb), whih produed a tensile stress of approxi'm'! mately 4 kpa (.6 psi), was slowly applied to the speimens in the stati tests to prevent impat loading and to minimize the effet of seating of the loading strip. The speimen was then loaded at a onstant deformation rate of 51 mm (2 in.) per minute. Vertial deformations were measured by a DC linear variable differential transduer (LVDT). Horizontal deformations were measured by two antilevered arms with attahed strain gauges. Both the loadvertial deformation and loadhorizontal deformation relationships were reorded by a pair of XY plotters, Hewlett Pakard Models 7lA and 7AR for the repeatedload tests. A preload of 9 N (2 Ib) was also applied. The desired load was applied at a frequeny of one yle per seond (1 Hz) with a.4seond load duration and a.6seond rest period. Both the horizontal and vertial deformations were measured by DCLVDT's and were reorded on the XY plotters. A typial load pulse and the resulting deformation relationships are shown in Figs 3 and 4. All tests were onduted at 24 C (75 F). PROPRTIS Several of the properties analyzed are related to the relevant pavement distress modes of (1) thermal or shrinkage raking, (2) fatigue raking, and (3) permanent deformations, or rutting. The properties analyzed were AVR density, total air oids, tensile strength,

21 1 Load Cyle at any Instant o.. o... : o o!1 u.. (a) Time Loadtime pulse. ' : L L L L > Time : o o... o I N... o J: (b) () Vertial deformation vs time. Time Horizontal deformation vs time. Fig 3. Typial load pulse and relationships between deformations and time for repeatedload indiret tensile test.

22 11 o o ' o o o u ' > 14 Permanent Deformation Vp o Nu m ber of Load Appl ialions N f =Fatigue Life Fig 4. Relationship between number of load appliations and vertial deformations for the repeatedload indiret tensile test.

23 12 stati Poisson's ratio, stati modulus of elastiity, fatigue life, resilient Poisson's ratio, resilient modulus of elastiity, and permanent deformation. The properties and equations used to alulate these properties (Refs 11 and 24) are disussed in the following setions. Tensile Strength The ultimate tensile strength is a measure of the maximum stress whih the mixture an withstand and is related to thermal and shrinkage raking resistane. The ultimate tensile strength was alulated using the following relationships for 152 mm (6 in.) diameter speimens and the loaddeformation information obtained from the stati indiret tensile test: =.15 P 1 u t t where = ultimate tensile strength, psi, P ult the maximum load arried by the speimen, lb, and t = the thikness of the speimen, in. Tensile stresses produed by loads less than the maximum load also be alulated using the above equation. P ult an Stati Poisson's Ratio \) = 4.9 _.27 DR

24 13 where v DR stati Poisson's ratio, and deformation ratio, slope of the relationship between vertial deformation and horizontal deformation, inhes of vertial deformation per inh of horizontal deformation. Stati Modulus of lastiity The stati modulus of elastiity was determined by analyzing the loaddeformation relationships for stati tensile tests. A regression analysis was onduted on data points up to a sharp infletion point in the loaddeformation urves, whih generally ourred between 6 and 9 perent of the ultimate load. If a sharp break in the urve was not present, data points were inluded up to a point about midway between the ultimate load and the deviation from linearity (Ref 2). The equation used to alulate the stati modulus was = s Sh t (.27 + v) where s Sh stati modulus of elastiity, psi, and slope of the relationship between axial load and horizontal deformation, i.e., the ratio of axial load to horizontal deformation within the linear range, lb/in. Fatigue Life Fatigue life is defined as the number of load appliations at whih the speimen will no longer resist load or at whih deformation is exessive and inreases with essentially no additional loads (Fig 4).

25 14 Resilient Poisson's Ratio The resilient Poisson's ratio v was dtermined from the repeatedload R tests and alulated using the resilient vertial and horizontal deformations (Fig 3) V and HR for the loading yle orresponding to.5 N The R f equations are the same as those used for the stati Poisson's ratio; however, sine the relationships between load and deformation are essentially linear, the equations have been modified and expressed as follows: = V R where and V R are the resilient horizontal and vertial deformations as shown in Fig 3. The values of resilient Poisson's ratio were used to alulate resilient modulus of elastiity but were not analyzed. The values, however, are listed in Appendix D. Resilient Modulus of lastiity The resilient modulus of elastiity was alulated using the resilient, or instantaneously reoverable, horizontal and vertial deformations whih are more harateristi of the elasti deformations produed by repeated loads of short duration. The equation used to alulate the resilient modulus was where = resilient modulus of elastiity, psi, and the applied repeated load, Ib (Fig 3a).

26 15 AsphaltVoids Ratio Density The AsphaltVoids Ratio, AVR, density was alulated using the mold diameter and the measured height, whih was obtained while the speimen was subjeted to the final ompation load of 345 kpa (5 psi). This is also referred to as the inmold density and is used to alulate perent total air voids as defined by Test Method Tex126. The speimen weight was determined after extrusion from the mold. The AVR density, in pf, was determined aording to the following equation: AVR Density = D W 2 H nd 4 where w = H = weight of speimen, Ib, height of speimen in mold while subjeted to final ompation pressure of 345 kpa (5 psi), ft, and D = diameter of mold, ft. Total Air Voids In order to obtain the perent total air voids, the following value was determined as speified by Test Method Tex126: Zero Air Voids Density (ZAVD) 1 'Y w P P +.!. G G s a

27 16 where = unit weight of water, P s P a G s G a = = perent dried aggregate by weight of the total mixture, perent asphalt by weight of the total mixture, absolute speifi gravity of the aggregate (obtained by performing Test Method Tex19, Part IV, using the pressure pynometer), and speifi gravity of the asphalt (from asphalt tests, Table 1). The perent total air voids was determined from this relationship: Perent Total Air Voids 1 _ AVR density of speimen X 1. ZAVD Permanent Deformation The parameter seleted as the basis for omparing the relative resistane to permanent deformation among the various speimens tested was permanent vertial deformation per yle. This value was alulated as the slope of a straight line fitted by least squares regression to data points desribing the relationship between permanent vertial deformation and number of load appliations (Fig 4). Only the portion of the relationship between.1 N and f.7 N was used. Several other parameters relating to permanent deformation f harateristis were investigated and found to be of little value. For the purpose of prediting permanent deformations in the field, permanent vertial strain would be more useful than permanent vertial deformation per,'yle. Permanent strain was not used for this analysis beause permanent horizontal deformations were not measured in the repeatedload tests. Therefore, Poisson's ratio for umulative permanent deformation ould not be obtained.

28 17 TSTING PROGRAM The variables inluded in this study were aggregate type, soil binder ontent, asphalt ontent, and moisture ontent. These variables were studied aording to the testing program outlined in Figs 5 and 6. These tests were performed at room temperature, 24 C (75 F). For the repeatedload tests, two stress levels (Table 3) whih would produe reasonable fatigue lives were seleted. A limited number of mixtures were tested to evaluate the effets of moisture. These mixtures ontained the optimum asphalt ontents for maximum tensile strength.

29 " agle Lake Gravel AC2 Lubbok Limestone ACI (,! B.O T L TR =:; H T TR,::... L H T L T R H T L TR = H T L TR H T L TR f= H I B.5 I 2 i I I I i I Fig 5. Summary of tests for agle Lake gravel and Lubbok limestone mixtures. l'

30 Lubbok Limestone AC TS I (63.1) TR 2 TR TS 2 TS 296 TR 2 TR (42.9) TS I 2 TS 313 TR 1 2 TR (54.1) TS 1 2 TS ori'" TR (52.3) a. I J I (26.2) (26.2) (26.2) TR '''' 1 (26.2) T5 stati indiret tensile test TR repeatedload indiret tensile test I 1181 TR (26.2) TS agle Lake Gravel AC Fig 6. Summary of tests for moisture damage of agle Lake gravel and Lubbok limestone mixtures. b. t' \.

31 2 TABL 3. STRSS LVLS FOR RPATDLOAD INDIRCT TNSIL TSTS Soil Binder Stress Level, kpa (psi) Mixtures Content, % Low L High H 3 4 (5.S) 12 (17.4) 2 4 (5.S) 12 (17.4) agle Lake gravel 1 4 (5. S) 12 (17.4) 5 SO (11.6) 12 (17.4) 7 (1.2) 12 (17.4) (21. S) 25 (36.3) Lubbok limestone 1 17 (24.7) 27 (39.2) 5 2 (29.) 3 (43.5) 15 (21.S) 25 (36.3)

32 CHAPTR 3. ANALYSIS AND DISCUSSION OF TST RSULTS The purpose of this study was to investigate the effet of the amount of soil binder on the engineering properties of asphalttreated materials. The following engineering properties were evaluated: General Total air voids Density Stati Charateristis Tensile strength Stati modulus of elastiity RepeatedLoad Charateristis Fatigue life Resilient modulus of elastiity Permanent deformation The experimental approah was to determine the relationships between asphalt ontent and the above engineering properties and determine the optimum asphalt ontent for eah property. These relationships and optimums were then evaluated with respet to soil binder ontent to determine whether properties ould be improved by ontrolling the binder ontent. Finally, the effet of moisture on these relationships was evaluated. AVR DSIGN OPTIMUM ASPHALT CONTNT The total air voids were alulated using the inmold AVR density and zero air void density as desribed in Chapter 2. The relationships between asphalt ontent and total air voids were determined for eah aggregate gradation. From these relationships the laboratory AVR design optimum asphalt ontent for eah aggregate gradation was determined aording to Test Method Tex126 (Ref 17). The laboratory AVR design optimum asphalt ontents are slightly greater than the asphalt ontents orresponding to the infletion point on the straight line setion of the AVR urves. The laboratory AVR 21

33 22 design optimum asphalt ontents, the orresponding total air voids, and the effet of the soil binder ontent are disussed in the following setions. agle Lake Gravel The relationships between asphalt ontent and total air voids are shown in Fig 7. These relationships indiate (1) that as the amount of soil binder dereased from 3 perent to 5 perent the total air voids dereased and (2) that the total air voids inreased appreiably as the amount of soil binder dereased from 5 perent to perent. It an be noted that the total air voids were approximately the same for binder ontents of 5 and 1 perent. The relationships between soil binder ontent and total air voids at asphalt ontents of 3., 3.5, and 4. perent are shown in Fig 8. The data for these urves were taken from Fig 7. These relationships indiate that the minimum total air voids ourred at a binder ontent of about 7 perent for mixtures ontaining 3. and 3.5 perent asphalt and at a binder ontent of about 1 perent for mixtures ontaining 4. perent asphalt. An AVR design optimum asphalt ontent was determined for eah binder ontent. It an be observed (Fig 9a) that the laboratory AVR design optimum asphalt ontent dereased from 4.5 perent for a 3 perent binder ontent to a minimum value of 3.5 perent for a 5 perent binder ontent and then inreased slightly to 3.6 perent for zero perent binder ontent. The relationship in Fig 9b shows that the orresponding total air voids at laboratory AVR design optimum asphalt ontent remain onstant at 1.6 perent for values of soil binder ontent ranging between 5 and 2 perent but inrease appreiably for perent and 3 perent binder ontents. Lubbok Limestone The AVR urves for Lubbok limestone are shown in Fig 1, whih suggests that, as the amount of soil binder dereased from 25 perent to 1 perent, the total air voids dereased to a minimum and then inreased as the amount of soil binder dereased further from 1 to perent. The relationships between soil binder ontent and total air voids at 5.5, 6., and 6.5 perent asphalt ontent are shown in Fig 11. The mixture ontaining 1 perent binder had the lowest total air voids regardless of the perentage of asphalt ontent. The relationships between soil binder ontent and (a) laboratory AVR design optimum asphalt ontent and (b) total air voids are shown in Fig 12.

34 23 6. % Binder A :J 5. )( 3 : :::J >. 4. > en ' > 2. «. 1. o.o Asphalt Content, % by Wt of Total Mixture Fig 7. Relationships between asphalt ontent and total air voids for agle Lake gravel mixtures.

35 % Aspha It Content Go» ' ::;, )( : Go» ::;, > a,.....,. " >.... « a 2. l e a IU : 1.. L..._"..I....J......L._ o Soil Binder Content, % by Wt of Total Aggregate Fig 8. Relationships between soil binder ontent and total air voids for agle Lake gravel mixtures.

36 25 :::I >.Q I Q. :::I o )( ::.. 1 :: II) :: ::: u 3..e (a).q Q. 2. II)...J «:: 1 4. II) a... ::: > >.Q <t.q.. I.. :::I )( ::...J :: II 3..., 2. II)... " U > a.e l :::I. Q. II) <t <t > :::I :: a Q. :i 1.. (b) Soi I Bi nder Content, / by Wt of Toto I Agg regote Fig 9. Relationships between soil binder ontent and (a) laboratory AVR design optimum asphalt ontent and (b) total air voids, for agle Lake gravel mixtures.

37 \. / Binder.& \ 25 ' ::J. )( \ 13. e. ::J \ > \ 12.. > " ' > '. «1.. \ \. \ 9. \ Aspha It Content, % by Wt of Tota I Mixtu re Fig 1. Relationships between asphalt ontent and total air voids for Lubbok limestone mixtures.

38 o 5.5 % Asphalt Content 6. G) ' )( : 14. G) > >. II) " >. ' ::( G) :: o Soil Binder Content, % by Wt of Toto I Aggregate Fig 11. Relationships between soil binder ontent and total air voids for Lubbok limestone mixtures.

39 28 e :J!to 9. e ;>...Q... :J 8. C.. M.; ; 2 7. o a : {!. > 6. ex a s:...q Q. ( a) a en 5...J ex tjl en a {!. a: ;> Q a.. :J..Q..J )( a 2 en 1. " > u a... s:. e :J. Q. ex en ex > a 9. {!. :J a Co 8. (b) Soi 1 Bi nder Content t OJo by Wt of Tota 1 Aggregate Fig 12. Relationships beteen soil binder ontent and (a) laboratory AVR design optimum asphalt ontent and (b) total air voids for Lubbok limestone mixtures.

40 29 Laboratory AVR design optimum asphalt ontents were 6.6 perent for both 5 perent and 1 perent soil binder ontents; however, the optimum asphalt ontents are higher for 25 perent soil binder ontent (7.3 perent) and perent soil binder ontent (6.9 perent). For eah soil binder ontent, the total air voids at laboratory AVR design optimum asphalt ontent are very lose, ranging from 9. perent for perent soil binder ontent to 8.6 perent for 25 perent soil binder ontent (Fig l2b). DNSITY The relationships between asphalt ontent and inmold AVR density for agle Lake gravel are shown in Fig 13. It is not shown, but the inmold AVR densities were generally larger than the densities of the top and bottom setions of the speimens, an observation whih had also been made in a previous study (Ref 24). From Fig 13 it an be seen that the mixture with 3 perent soil binder ontent had the lowest inmold AVR density while the mixtures with 5 and 1 perent binder ontents had the highest inmold AVR densities. The relationships between soil binder ontent and inmold AVR density for mixtures with asphalt ontents of 3., 3.5, and 4. perent and agle Lake gravel are illustrated in Fig 14. The optimum soil binder ontents were about 7 perent for mixtures with 3. and 3.5 perent asphalt ontents. density urve for 4. perent asphalt ontent interseted the urve for 3.5 perent asphalt ontent at about 14 perent soil binder ontent. The This indiates that the same density an probably be obtained by using either 3.5 or 4. perent asphalt ontent with 14 perent soil binder. At soil binder ontents less that 14 perent, mixtures with 3.5 perent asphalt ontent had higher densities that those with 4. perent asphalt ontent; at soil binder ontents higher than 14 perent, the reverse was true. For the agle Lake gravel, the relationships between soil binder ontent and both the optimum asphalt ontent for inmold AVR density and the maximum inmold density are illustrated in Fig 15. It an be seen from these urves that the inmold AVR density inreased with dereased soil binder ontent, until it reahed a maximum (2447 kg/m 3 ) at 5 perent soil binder ontent. Figure 15 also indiates that mixtures with 5 perent binder ontent had the lowest optimum asphalt ontent (3.5 perent) and the highest maximum density, kg/m (153 pf), and that the optimum asphalt ontent for inmold AVR

41 , ''' rt') " ' > en Q A /.J U Q. >: en Q 236 % Binder 147.6; 5. ' Asphalt Content, / by Wt of Total Mixture 145 Fig 13. Relationships between asphalt ontent and inmold AVR density for agle Lake gravel mixtures.

42 " e... CI > II) II) 24 A C 15 Q> 149 Q Q 238 Q> Q> 148 u Q.. > C Q> % Aspho It Content o Soj I Binder Content, / by Wt of Toto I Agg regate Fig 14. Relationships between soil binder ontent and both the optimum asphalt ontent and the orresponding inmold AVR density for agle Lake gravel mixtures.

43 32 :3 Q. >..Q.. )( S.O G.I ' 5. C u :i 4. u I 3.. Q. II) «2. (a) 238(_b_) o Soil Binder Content, % by Vlt of Totol Mixture 149 Fig 15. Relationships between soil binder ontent and (a) the optimum asphalt ontent for inmold AVR density, and (b) the orresponding inmold AVR maximum density for agle Lake gravel mixtures.

44 33 density (Fig l5a) was lose to the laboratory AVR design optimum asphalt ontent (Fig 9a) for eah binder ontent. For Lubbok limestone, the relationship between asphalt ontent and inmold AVR density is shown in Fig 16. As previously noted, the inmold AVR densities were generally greater than the top and bottom densities and the density of the bottom speimens were generally r than that of the top speimens. Figure 16 shows that the mixtures with 25 perent soil binder ontent had the lowest inmold AVR density while the mixture with 1 perent soil binder had the highest inmold AVR density. The optimum soil binder is about 1 perent for 5.5, 6., and 6.5 asphalt ontent and about 5 perent for 7. perent asphalt ontent (Fig 17). The relationships between soil binder ontents and both optimum asphalt ontent and the orresponding inmold AVR maximum density for eah soil binder are shown in Fig 18. The highest maximum density, 222 kg/m 3 (139 pf), ourred at about 8 perent soil binder and 6.5 perent optimum asphalt ontent. The optimum asphalt ontent for maximum inmold AVR density dereased from 7.5 perent for 25 perent soil binder ontent to 6.5 perent for 1 and 5 perent soil binder ontents and then inreased to 7.3 perent for perent soil binder ontent. STATIC INDIRCT TNSIL TST RSULTS The engineering properties, tensile strength and stati modulus of elastiity, were estimated using the stati indiret tensile test. Values of ultimate tensile strength and stati modulus of elastiity for individual speimens are presented in Appendix C along with the measured values of Poisson's ratio. Tensile Strength The effet of asphalt ontent on ultimate tensile strength was determined (Figs 19 and 2) and optimum asphalt ontents were found for eah soil binder ontent and eah aggregate type. Values of optimum asphalt ontent for the agle Lake mixture ranged from 3. perent for soil binder ontents of 5 and 1 perent to 4. perent for a binder ontent of 3 perent (Fig 2la), and from 5.5 perent for a binder ontent of 1 perent to 7. perent for a binder ontent of 25 perent for the Lubbok limestone mixtures (Fig 22a). The maximum tensile strength was 1,365 kpa (198 psi) (Fig 21b) for the

45 f,a 137 '''". 218,/ 136 / rt), J 135 '" at.jt! 216 > + ( CII : CI Q1 134 : Q , / I,, J, 133 % Binder ' 1, (). > + CII : Q1 CI : Q1 28 L L J Aspha It Content, % by Wt of Toto I M ixtu re Fig 16. Relationships between asphalt ontent and inmold AVR density for Lubbok limestone mixtures.

46 u " C7I 216 Q..... > > en en : : u u 134 : : 214 u u :!: Fig 17. Relationships between binder ontent and inmold AVR density for Lubbok limestone mixtures.

47 36 ::J Q. 9. >.l:l a JC. ::J 8.., C 7. u o 6..&:. Q. en 5. (a) rt)... 1.lI: a >CIt C 222 C U Q. a >en C 218 L..,.;...(b...;;..) ' '..L......l..._...I o to 2 3 Soi I Bi nder Content, % by Wt of Toto I Agg regote Fig 18. Relationship between soil binder ontent and (a) optimum asphalt ontent for inmold AVR density, and (b) the orresponding inmold AVR maximum density for Lubbok limestone mixtures.

48 % Binder A Q..lII: 2 2 en ' ' at C C 15.,.. ' (/) (/) ". ". CD 8 ēn en CD b CD 1'.r::... 4, 5 1 I I I I I I 1 o Aspha It Content, / by Wt of Tota I Mixture Fig 19. Relationships between asphalt ontent and tensile strength for agle Lake gravel mixtures. W..J

49 16 I o % Binder ,.o. / Q. /. / ".. A 12.s:::. "'./\ \ CI C... (f) \ d.5 '1 1 tj,... en \ '25 \ lit Q. A.s:::. CI C... (I') en I 8 " 12 "' 'D 1 6' Aspha It Content, % by Wt of Toto I Mix tu re Fig 2. Relationships between asphalt ontent and tensile strength for Lubbok limestone mixtures. w

50 39 A ti )(... ti ::I u a. en «5 :I 4.s; {:. :3 2 ::I >...:2 (a) o 1 16 o 12 2 a. en.:rtf.. A 15 A s:. s:. ' ' C... " 8 (I) (I) 1 en C en... o (b) o Binder Content, / by Wt of Toto I A gg regate o Fig 21. Relationships between binder ontent and both the optimum asphalt ontent and the orresponding maximum tensile strength for agle Lake gravel mixtures.

51 :: Cit :: 7. Cit u_... _ :::J 6.5 i )(.>en., «o {!. 6. :::J 5.5 (a) Q.. en '1 C' :: :: Cit Cit (/) (/) Cit en :: Cit t 1 en 14 :: Cit Binder Content, / by Wt of Total Aggregate Fig 22. Relationships between binder ontent and both the optimum asphalt ontent and the orresponding maximum tensile strength for Lubbok limestone mixtures.

52 41 agle Lake gravel mixture and 1,367 kpa (2 psi) (Fig 22b) for the Lubbok limestone mixture, both of whih ourred at a binder ontent of 5 perent. The maximum tensile strengths of the agle Lake mixtures at binder ontents of 3, 2, and 1 perent were essentially equal at about 119 kpa (173 psi); however, the optimum asphalt ontents were 4., 3.5, and 3. perent respetively (Fig 21). As the soil binder ontent dereased from 1 to 5 perent the strength inreased by 18 kpa (26 psi) while the optimum asphalt ontent remained onstant at 3. perent. Without any soil binder ontent, the ultimate tensile strength of the agle Lake gravel mixture dereased signifiantly, while the mixing optimum asphalt ontent inreased from 3. to 3.5 perent. Similar trends were found for the Lubbok limestone mixtures, exept that the optimum asphalt ontents for 5 and perent binder ontents (Fig 22) were the same (6. perent). For the purpose of omparison, the relationships between binder ontent and tensile strength per 1 perent optimum asphalt ontent were evaluated (Fig 23). It an be seen that the agle Lake gravel mixture with 5 perent soil binder ontent produed the maximum ultimate tensile strength per unit perent of optimum asphalt ontent with a value of 456 kpa per one perent optimum asphalt ontent (66 psi per one perent optimum asphalt ontent) while the Lubbok limestone mixture with 1 perent binder ontent produed the maximum tensile strength per unit perent of optimum asphalt ontent with a value of 246 kpa per one perent optimum asphalt ontent (36 psi per one perent optimum asphalt ontent). Stati Modulus of lastiity The relationships between asphalt ontent and the stati modulus of elastiity for agle Lake gravel and Lubbok limestone mixtures are shown in Figs 24 and 25 For all mixtures there were optimum asphalt ontents for maximum stati moduli of elastiity. These optimum asphalt ontents for agle Lake gravel mixtures ranged from 3. perent for, 5, and 1 perent binder ontents to 4. perent for 2 and 3 perent binder ontents (Fig 26a). For Lubbok limestone mixtures the optimum ranged from 6. perent for 5 perent soil binder ontent to 7. perent for 25 perent soil binder ontent (Fig 27a).

53 II) a.. a..li: A A 12 C 8 agle La ke Gravel u Lubbok Limestone u a. a. II) II) 6 <t <t 8 ::l ::l a. a. 6 4 u u a C C 2 (/) (/) II) II) Soil Binder Content, % by Wt of Total Aggregate Fig 23. Relationship between binder ontent and the tensile strength per unit perent of optimum asphalt ontent for agle Lake gravel and Lubbok limestone mixtures.

54 2.5 I,, o % Binder! 2.+ /\ / \ A5 l3 \ \ 2 1 A A > > Ū I/) 1.5. w :::) 1. I. ::. I/) :::) "C u (/).5 :: \. O.. '\ 'D.2.1 U I/) w I/) :::) :::) "C u (/) O' ' Asp hal teo n fen t, % by W f f Tot aim i x t u r e Fig 24. Relationships between asphalt ontent and stati modulus of elastiity for agle Lake gravel mixtures. +' UJ

55 2.5 : 2... :> u II) LLI II) ::J ::J "C : u (f) OJ : 1.5 /'.,..o../.\ ;:I % Binder 5 o 1 o _ o.5 o l3 i :>... u II).2 LLI II) ::J ::J "C : u.1. (f) OJ :: o Aspho It Con tent, % by Wt of Tota I M ixtu re 25. Relationships between asphalt ontent and stati modulus of elastiity for Lubbok limestone mixtures..po..po.

56 45 u ::J )( a. >_ en.q «::J t a. (a) 2.5 en a. CL. W 2..3 Wo en en 1.5 > > (.) (.) lij.2 lij en en ::J ::J ::J 1. ::J "C "C (.) (.).1.5 en en (b) Soil Binder Content, % by Wt of Total Aggregate : :e Fig 26. Relationship between soil binder ontent and both optimum asphalt ontent and the orresponding stati modulus of elastiity for agle Lake gravel mixtures.

57 46.. : u : u U J )(.z= ::.> If). <t a. (a) a.. If).lI::.4 a. w W.... > 2.5 >.35 w.3 2. u If) w If) ".25 " :: u (f) : : u u (b) u If) If) :: u (f) 1.5 Soi I Binder Content, / by Wt of Toto I Aggregate Fig 27. Relationships between soil binder ontent and both optimum asphalt ontent and the orresponding stati modulus of elastiity for Lubbok limestone mixtures.

58 47 For the agle Lake gravel mixtures the maximum stati modulus of elastiity ourred at 5 perent and 3 perent soil binder ontents (Fig 26b). It is not lear, however, whether a true maximum ourred at 3 perent. The optimum binder ontent was found to be 1 perent for Lubbok limestone mixtures (Fig 27b). Figure 28, whih illustrates the relationships between soil binder ontent and modulus per one perent of optimum asphalt ontent, indiates a trend similar to that observed for tensile strength. The modulus per one perent optimum asphalt ontent was maximum at binder ontents of 5 and 1 perent for agle Lake gravel and Lubbok limestone mixtures, respetively. Thus, in terms of eonomy of the mixture, the optimum binder ontents would be 5 and 1 perent, whih is the same as the optimum for maximum stati modulus of elastiity. RPATDLOAD INDIRCT TNSIL TST RSULTS Repeatedload indiret tensile tests were onduted to evaluate the fatigue life, resilient modulus of elastiity, and resistane to permanent deformation for eah of the mixtures of agle Lake gravel and Lubbok limestone. Results of repeatedload tests for individual speimens are presented in Appendix D. Fatigue Life For indiret tensile tests, stress differene was assumed equal to 4 times the tensile stress T. In order to eliminate the effet of stress and to determine the effet of asphalt ontent and binder ontent, the fatigue life of the mixtures was evaluated for a tensile stress of 1 kpa (14.5 psi) for eah binder ontent. As shown in Figs 29 and 3, an optimum asphalt ontent for maximum fatigue life was found for eah of the mixtures of agle Lake gravel and Lubbok limestone. It an be noted that these relationships were essentially symmetrial, i.e., the redution in fatigue life wet of optimum was the same as that dry of optimum. The relationships between soil binder ontent and the optimum asphalt ontents are shown in Figs 3la and 32a. Optimum asphalt ontents for the agle Lake mixtures ranged from 2.9 perent for 5 perent binder ontent to 4.6 perent for 3 perent binder ontent (Fig 3la) and from 4.5 perent

59 a.....,:,e. en a. U) o ag Ie La ke Grave I.25 U) > > Lubbok Limestone u : u 1.5 : en en :.2 : Lt.J U IJJ U en en.s;; :J.15 :J.s;; a. 1. a. :J en :J en ' ::( ' ::( :J U.1 u :J a. (/) (/) a..5 : : :.5 : u u... a..... a Soil Binder Content, / by Wt of Total Aggrega te... a..... a. Fig 28. Relationship between binder ontent and the stati modulus of elastiity per unit perent of optimum asphalt ontent for agle Lake gravel and Lubbok limestone mixtures.

60 49 o 8 o % Binder A 5 '1 '2 3 C» u > u...,.. C»...J C» :J OIl. LL "CJ C» LLJ 6 4 / / / 2 /. I. J I Aspha It Con ten t, % CT T = 1 kpo (14.5 psi) by Wt of Total Mixture 29. Relationships between asphalt ontent and fatigue life for agle Lake gravel mixtures.

61 5 en u > u,." I...J % Bi nder 5 1, '1 I \.. \ I.. '25. f.. \ CI. )Y' /. I LL J ' en 1 w I 6. \. 1 O"T = 1 kpa (14.5 psi) Asphalt Content, % by Wt of Total Mixture Fig 3. Relationships between asphalt ontent and fatigue life fot Lubbok limestone mixtures.

62 51.. :;, )( " 6. u 5..s::. J 4. en <t 3. :;, 3: >.. ( a) 2. en 1 8 (.J 6 >. (.J rt')..j 4 :;, 1... O"T= " 1 kpo (14.5 psi) 2 en I.&J I (b) o Binder Content, % by Wt of Total Aggregate Fig 31. Relationships between binder ontent and both optimum asphalt ontent and the orresponding fatigue life for agle Lake mixtures.

63 52.. G.I " G.I ::J : )( o. u: : /1 «::J3: 5. >...Q (a) Q /1 G.I (.) 6 > (.) rt').. G.I 4...J G.I ::J ' LL ' G.I 2 1/1 ILl O"T = 1 kpo (14.5 psi) 1 L(:...,b.=).I. L L..L o Binder Content, % by Wt of Total Aggregate Fig 32. Relationships between soil binder ontent and both optimum asphalt ontent and the orresponding fatigue life for Lubbok limestone mixtures.

64 53 for 1 perent binder to 7.5 perent for 25 perent binder for the Lubbok limestone mixtures (Fig 32a). For both mixtures the optimum asphalt ontent for perent soil binder ontent was higher than the optima for mixtures with 5 and 1 perent soil binder ontents (Figs 3la and 32a). The optimum soil binder ontent for maximum estimated fatigue life was 5 perent for both types of aggregate (Figs 3lb and 32b). The maximum estimated fatigue life was about 87 yles for the agle Lake gravel at 2.9 perent asphalt ontent and was about 98, yles for the Lubbok limestone at 6. perent asphalt ontent. The relationships between binder ontent and estimated fatigue life per one perent optimum asphalt ontent are shown in Fig 33. These relationships indiate maximum eonomy ours at binder ontents between 5 and 1 perent for the Lubbok limestone mixtures and at approximately 5 perent for the agle Lake gravel mixtures. The latter is the same as the optimum binder ontent for maximum fatigue life; however, for the Lubbok limestone mixtures the optimum for maximum fatigue life was well defined at 5 perent rather than over a range between 5 and 1 perent. Resilient Modulus of lastiity The relationships between asphalt ontent and the resilient modulus of elastiity at.5 N are shown in Fig 34 for agle Lake gravel mixtures and f Fig 35 for Lubbok limestone mixtures. Both figures indiate that the optimum asphalt ontent for maximum resilient modulus is not well defined, with most of the relationships being flat. This behavior is onsistent with the behavior reported by other investigators (Refs 1 and 26). Nevertheless, to analyze the effets of binder ontent an attempt was made to pik an asphalt ontent whih produed the maximum modulus. The resulting relationships between soil binder ontent and optimum asphalt ontent for maximum resilient modulus of elastiity for the loading yle orresponding to.5 N are shown in Figs 36 and 37. The maximum resilient f moduli of elastiity for agle Lake mixtures with 5 and 3 perent soil binder ontents were about 2.5 times those for, 1, and 2 perent soil binder ontents. Thus, either 5 or 3 perent may be hosen as the optimum soil binder ontent; however, the urve is not well defined. The optimum binder ontent for maximum resilient modulus of elastiity for the Lubbok limestone mixtures was 1 perent with 5.5 perent asphalt ontent.

65 o 6. u 4. Lu bbok Limestone / 2. o C QJ U QJ a \L. "C QJ ;.8 LaJ.6 agle Lake Gravel /.5 o Binder Content, % by Wt of Toto I Agg regate Fig 33, Relationships between binder ontent and the estimated fatigue life per unit perent of optimum asphalt ontent for agle Lake gravel and Lubbok limestone mixtures.

66 5,7 o Q..lilt! <II o 4.6!II). U)o :: LaJ ::lioo!..5 :: W ::lioo!. (.) en..2 LaJ o en '::J '::J "C o :: : u en U :: 3 2 D,o... "J.( _. ',:J % Binder.2 & IO (.) en o W o en '::J '::J "C o :: : u.,. Q.I ::: Asphalt Content, % by Wt of Total Mixture Fig 34. Relationships between asphalt ontent and resilient modulus of elastiity at O.5N f for agle Lake gravel mixtures. VI VI

67 Q...lI: U) o en CD o a:: w >u en C W o CIt :J :J " o ::: CI) 3 2 CY"" ' D % Binder A 5.O.. /" \J._. d a:: w >u en C W o en :J :J " o ::: CI) en CI) a:: I, 1.I ' o en CI) a:: Asp h a I teo n ten t I / by W t f Tot a I Mix t u r e Fig 35. Relationships between asphalt ontent and resilient modulus of elastiity at O.5N f for Lubbok limestone mixtures. V1 \

68 57 It' Cl) Cl) ::l 6. )( 5. u Q. en «4. ::l 3. >. Q > > (,).6 (,) en 4 en L.&.I L.&.I Q...5 en Q. en en ::ltd 2( ::l ' ::l ' Cl)...4 :: : L.&.I Cl).. :: L.&.I en :: 2.3 en ::.2 o Bi nder Content, % by Wt of Toto I Agg rego t e Fig 36. Relationships between soil binder ontent and both maximum resilient modulus of elastiity at O.5Nf and the orresponding optimum asphalt ontent for agle Lake gravel mlxtures.

69 58 : :::s 9. : )( u ::!:.: 8... en 7. «:::s ;= > ><.J 5.7 ><.J en w 4 en :::s :::s C a...:.t. 'Ow ::!: 3 : ::: w en a:: 2 ::!: en C W en :::s en.. :::s '<. ::!: a:: : w en a:: ::!: o Binder Content, % by Wt of Toto I Agg regote Fig 37. Relationships between soil binder ontent and both maximum resilient modulus of elastiity at O.5Nf and the orresponding optimum asphalt ontent for Lubbok limestone mixtures.

70 59 Sine it would appear that the atual asphalt ontent is not ritial to resilient modulus of elastiity and sine the atual values of modulus were relatively onstant, the minimum values of asphalt ontent should be used. Permanent Deformation The effets of asphalt ontent on the rate of vertial permanent deformation for eah binder ontent and stress level are shown in Figs 38 through 42 for agle Lake gravel and in Figs 43 through 46 for Lubbok limestone. As in previous studies (Refs 1 and 23), an optimum asphalt ontent for minimum rate of permanent deformation was found to our. Values of rate of permanent deformation for eah binder ontent for eah of the two mixtures are presented in Appendix. For a onstant stress level of 12 kpa (17.4 psi), the relationships between the soil binder ontent and both the optimum asphalt ontent and the orresponding minimum rate of permanent vertial deformation for agle Lake gravel mixtures for a stress level of 12 kpa (17.4 psi) are shown in Fig 47. Optimum asphalt ontents ranged from 3. to 4. perent and the optimum binder ontent was 5 perent. For Lubbok limestone, the applied stress was different for the various mixtures. However, Fig4B suggests that the optimum binder ontent for the lowest minimum rate of permanent deformation was approximately 1 perent for the Lubbok limestone mixtures. It should be noted that the optimum asphalt ontent for minimum rate of permanent deformation appeared to be stress dependent. For the agle Lake mixtures the optimum asphalt ontent for minimum rate of permanent deformation was generally smaller for a higher stress level. For the Lubbok limestone mixtures this relationship was not well defined. Moisture Damage This study generally indiated that the optimum soil binder ontents for maximum engineering properties were relatively low, in the range of 5 to 1 perent. In addition, these low binder ontents required less asphalt and therefore improved the eonomy of the mixtures. However, the speimens tested were dry and had not been subjeted to moisture. Thus, it was neessary to evaluate the effets of water on the engineering properties of the two materials as disussed in Chapter 2. A series of speimens for eah aggregate type at the optimum asphalt ontent for the maximum ultimate tensile strength were

71 6 1, 4 rt = 12 kpa (l7.4 psi) u > u... u > u to ' to A 1 b : : ' : C : 1, : : ' a. ' a. u ' rt = 4 kpa (5.8 psi) u >... > 1 a: ' a: Asp h a I teo n ten t, / by W t f Tot a I Mix t u r e Fig 38. Relationships between asphalt ontent and rate of permanent deformation for agle Lake gravel mixtures with 3 perent binder.

72 61 1, 4 O'"T =12 kpo (17.4 psi) >... > (D ' (D : 1 '... Cl : :... a.. 1, O'"T = 4 kpo (5.8 psi)... >... > a:: 1 :... Cl : :... a. a:: Aspho It Content, % by Wt of Toto I M ixtu re Fig 39. Relationships between asphalt ontent and rate of permanent deformation for agle Lake gravel mixtures with 2 perent binder.

73 62 5, 2 CTT = 12 kpo (17.4 psi) 1 >... >... (, ' (,.. '.. 1, \.. C a a e \.. C e a. \.. 1 C > CT T = 4 kpo (5.8 psi) C a. \.. \..! > a::: C 1 \.. a::: Aspho It Content, % by Wt of Toto I Mixture Fig 4. Relationships between asphalt ontent and rate of permanent deformation for agle Lake gravel mixtures with 1 perent binder.

74 63 1, 4 1 L. ' L...I... = Asphalt Content, % by Wt of Total Mixture Fig 41. Relationships between asphalt ontent and rate of permanent deformation for agle Lake gravel mixtures with 5 perent binder.

75 64 1, 4 U) v O'"r = 12 kpo (17.4 psi) > v v v ""t... > '.. 1 '.. I. I. 1, O'"r = 7 kpo (1.2 psi) I. I. v l. V > I. > 1 :: U) a:: 1 '_ ' 1...1_=: Asphalt Content, / by Wt of rotol Mixture Fig 42. Relationships between asphalt ontent and rate of permanent deformation for agle Lake gravel mixtures with perent binder.

76 65 QJ,.. 3,... «> '.. 1, : ' QJ : : O""T = 25 kpa (36.3 psi) O""T =15 kpa (21.8 psi) ' a.. 1 ' > a:: 1 1 QJ,....., : «> '.. : ' Cl : QJ : ' a.. ' > a:: Asphalt Content, / by Wt of Total Mixture Fig 43. Relationships between asphalt ontent and rate of permanent deformation for Lubbok limestone mixtures with 25 perent binder.

77 66 (U 1. IOO.! 1 u :>. u u :>.... u... : CD CD 1 at = 2. 7 kpa (39.2. psi) I.. ' (U (U... (U 1 ' (U a... u... a T = 17 kpa (2.4.7 psi) ' 1 (U > (U "" > (U (U ::... ' (U ' (U a... u :: Asphalt ontent, / by Wt of Total Mixture Fig 44. Relationships between asphalt ontent and rate of permanent deformation for Lubbok limestone mixtures with 1 perent binder.

78 67 3, CT T = 3 kpo (43.5 psi) 1 (.)» (.) (.)»... (.)..o 1.. 1, :.. : ' ' : : ' : CT T = 2 kpo (29. psi) : a.. 1 ' a.. () ' (.) > ' > 1 : :..o b Aspho It Content, % by Wt of Toto I M i xtu re Fig 45. Relationships between asphalt ontent and rate of permanent deformation for Lubbok limestone mixtures with 5 perent binder.

79 68 7, CT T = 25 kpa (36.3 psi) 3 IV U > U " U> ' 1 IV U > u ""\ : o + I o IV o C IV C I IV Q.. u I IV > o IV C a:: 1, CT T =15 kpa (21.8 psi) 1 o... o IV o C IV C I IV Q.. u I IV > o IV C a:: Asp h a It Con ten t, % by W t f To t a I Mix t u r e Fig 46. Relationships between asphalt ontent and rate of permanent deformation for Lubbok limestone mixtures with a perent mixtures.

80 _ 4. :::s C _.2 )( (.) 3t O..:. en t 3. <l' Q1 <.J > <.J 1, U> '.. o o ' o Q1 a Q1 o ' Q1 a. o <.J.". > ' Q1 > o Q1 o a:: a , O"T =12 kpa (17.4 psi) b. 4 o Binder Content, / by Wt of Total Aggregate Q1 u 4 > u <.D '.. e ' Q1 a C Q1 C ' Q1 Q.. u ' Q1 > Q1 a:: :: Fig 47. Relationships between soil binder ontent and both optimum asphalt ontent and the orresponding minimum rate of permanent deformation for agle Lake gravel mixtures.

81 OJ U > CD 1 : o o 'ō OJ Q : OJ : o ' OJ a. o (,) ' OJ > o OJ o a:: 4. '_.1 a , 1 25 kpa (36.3 psi) r... q 3 kpa (43.5 psi) \... \ /// 25 kpa ',,,/' (36.3 psi) CY' 27 kpa (39.2 psi) 15 kpa (21.8 psi) O"'... '"'q 2 kpa (29. psi) \ \ \ \ \ _ 15 kpa b (21.8 psi) 17 kpa (24.7 psi) b. o Binder Content, % by Wt of Total Aggregate 2.l.l.lL 4 OJ U, > (,) : CD '.. : o o 1 OJ Q : OJ : o ' OJ a. o (,) ' OJ > o OJ o a:: Fig 48. Relationship between soil binder ontent and both optimum asphalt ontent and the orresponding minimum rate of vertial permanent deformation at different stress levels for Lubbok limestone mixtures.

82 71 subjeted to pressure wetting and then were tested to obtain stati indiret tensile results and to obtain the resilient modulus of elastiity. Test results are shown in Figs 49 through 56. The relationships between binder ontent and the asphalt ontent, total air voids, water ontent after pressure wetting, and densities of the speimens are shown in Figs 49 and 5 for agle Lake gravel mixtures and in Figs 51 and 52 for Lubbok limestone mixtures. Total air voids and densities of tested speimens were not exatly the same as those obtained from the speimens used to establish the laboratory AVR relationships, but the values were lose. The asphalt ontents of tested speimens were lower than the optimum asphalt ontents for the maximum densities and thus the orresponding densities were less than the maximum densities and the air void ontents were higher. As shown in Figs 49 and 51 water ontents after pressure wetting were proportional to the total air voids, i.e., the higher the total air voids, the higher the water ontents. There was a definite effet of moisture on the ultimate tensile strength and the stati modulus of elastiity (Figs 53 and 55). A strength loss of about 25 kpa (36 psi) ourred for agle Lake gravel mixtures with 5 perent soil binder and of about 5 kpa (72 psi) for mixtures with 3 perent soil binder. However, pressure wetting did not produe a loss of tensile strength for mixtures with, 1, and 2 perent soil binder. For the Lubbok limestone mixtures the losses were more onsistent, varying from 75 kpa (11 psi) to 4 kpa (58 psi). The effet of pressure wetting on stati modulus of elastiity was more signifiant (Figs 53a and 55a). Losses in modulus for the agle Lake mixtures ranged from 1, kpa (14,5 psi) to slightly less than 1,, kpa (145, psi). Similarly, for the Lubbok limestone the losses ranged from about 4, kpa (58, psi) to 1,, kpa (145, psi). No onsistent or explainable relationships were observed for the resilient modulus of elastiity (Figs 54b and 56b). In most ases the pressure wetted speimens exhibited higher moduli than the dry speimens. This was espeially true for the Lubbok limestone mixtures. A omparison of the density relationships for tested speimens (Figs Ob and 52b) with the urves of the ultimate tensile strength and the stati modulus of elastiity after pressure wetting (Figs 53 and 55) indiates that the shapes are similar. Thus, it would appear that moisture damage was dependent on the density of the mixture, or air void ontent. It was found that the highest density

83 72 Q,) 5 A : ::J Q,) )( : u 3 4,&; 3= en > <X. 2 (a) Tested Speimens 8 8 DTotal Air Voids of Tes ted en Speimens Q,) Q,) 7 7 OTotal Air Voids from Laboratory ::J ::J )( )( AVR Relationships 6 Water Content After Pressure 6 Wetti ng 5 5 I > > = ' > en " 3 3 A > A..,."" Q,) <X 2 2 : u Q,) I (b) 3= Binder Con ten t, / by Wt of Toto I Aggregate. : Fig 49. Relationships between binder ontent and asphalt ontent, total air voids, and water ontent of speimens ontaining agle Lake gravel.

84 73.. IV Mali mu m Density \.D IV ::J C )( 6. Opti mu m Aspha It Content for the 5. u 3:.t:r' :: 4.,," > a.j:l a. \ Aspha It Content Q. 3. en l of Tested Speimens <:C,," 2. (a) P"'\A! I... I "' Maximum Density I " I I "'Q I \ \ \... \ 151 tj Q. C'I..x: \ >... \ > \ en en \ IV \ C Density of \ IV Tested Speimens from the AVR Density IV IV Curves 149 : 238 Density of Tested Speimens for Stati Indiret Tensile Test 148 D. Density of Tested 236 Spei mens for R Test (b) \47 Binder Content, / by Wt of Total Agg regate 5. Relationships between binder ontent and the asphalt ontents and densities of tested speimens of agle Lake gravel mixtures.

85 ' ::l C )( 7 u 3'; >. 6.s:; Tested Speimens.'... en «5 12 (a) Air Voids from La bora tory AVR II..., I Curves ' ::l I... )( 1 ' Air Voids of Tested... ::l )( 9 Spei mens ::l 8 >... Tota I Air Voids of Tested 3'; 7 Speimens... Total Air Voids from La bo > > 6... ratory AVR Relationships Do Water Content After Pres 5.. en su re Wetti ng 't:j > 4. ' «' b) Binder Content, / by Wt of Tota I Aggregate. u Fig 51. Relationships between binder ontent and asphalt ontent, total air voids, water ontent of speimens ontaining Lubbok limestone.

86 75 = >...s::. a. 11) I «9. Optimum Aspha It Content for Maximum Density 8. Q ",,,,() 7.,/ "...' 6. Aspha It Content of Tested Spei mens 5. '''' (a) ' i.. '_ rt)... 1.::t: A >II) JJo..j /... I... I... I ' o Maxi mu m Density Density of Tested Spei mens from the AVR Density Curves 134 Density of Tested Spei mens for 214 Stati Indiret Tensile Test b. Density of Tested Speimens for R Test 133 a. A >II) (b) 2 I 2 ''''12::'=3..J...: Bi nder Content, % by Wt of Toto I Agg reg ate Fig 52. Relationships between binder ontent and the asphalt ontents and densities of tested speimens of Lubbok limestone mixtures.

87 76 o a...:ii! o en o LLI o en ::J ::J ' o o o (/) ,D\ / I \ I \ I \ I \ I \ b I,, \ 6 \ Pressu re Wetted Dry (a).5 \ \ o en o LLI o en ::J ::J ' o o o (/) o a...:ii! A. CI C u \.. (/) u en {!!. u o o (b) Pressu re Wetted.l......L......L. L_J o Binder Conten"', % by Wt of Total Aggregate A. CI C u \.. (/) u en u I u o Fig 53. Relationships between binder ontent and moisture ontent on the ultimate tesnile strength and stati modulus of elastiity for agle Lake gravel mixtures.

88 77.. Q,) Air Voids from Laboratory AVR Curves 3: 4 \ren :: > Q,) "' Q,) )( > > / )( :.. Q,) o:: Air Voids of Tested Speimens : > Wa ter Content After Pressure u I I Wetti ng Q,) (a) I ;: 5 D I \.7 I \ I \ : I \ I Pressure Wetted \.6 : en : 4 \ I \ u I... I, *, ;l I.5 ;l \ : I I : I, "' 3 I I "' Q,) Q,) en I I I.4 en I / III I I / III I / I a.. f '" en CD 2... _.."",..3 D I.... a: Dry I.LJ (b) /.2 en u I.LJ a: Binder Content, % by Wt of Toto I Agg regate Fig 54. Relationships between binder ontents and air voids, water ontent, and resilient modulus of elastiity for agle Lake gravel mixtures.

89 78 o Q. fj) "'" o In o IJJ o U) 1.5 J:)o.. Dry 1..5 /... I /... I... <:5 """... ' Pressu re Wetted u=o.2,i In o IJJ o In :;J :;J " o <.J. o U) o Q. "'"...s:: 1 : QJ to.. U) QJ In : QJ o )1 "',I () o Dry Pressu re Wetted (b) oo o Binder Content, % by Wt of Total Aggregate In.....s:: 1 : QJ to.. U) QJ In : QJ... QJ o Fig 55. Relationships between binder ontent and moisture ontent on the ultimate tensile strength and the stati modulus of elastiity for Lubbok limestone mixtures.

90 79 14 Total Air Voids of 14 I Tested Speimens " 3: 1 1 Air Voids from the 1" I/) o.=! La bora tory AVR Curves ' > 8 8 >.. '. )( ' )(. C <1: I 6 6 Water Content After Pressure u.. > \ ' I Wetting 4 4 3: (a) /", Pressure I Wetted I/) /... u *.5 p """'''''''''', u / " *.4 3 / ' ;:) ;:) / d QJ QJ I/) I/) o o 2.3 CL a. ole Dry (D (D.2 (b) :: LLJ LLJ Bi nder Con tent t / by Wt of Tota I Aggregate I/) I/) :: Fig 56. Relationships between ontent and air voids, and water ontent, and resilient modulus of elastiity for Lubbok limestone mixtures.

91 8 for agle Lake gravel mixtures was ahieved at 5 perent soil binder ontent and for Lubbok limestone mixtures at 1 perent soil binder ontent. This would suggest that as long as the mixture has adequate density substantial damage will not our; however, it must be kept in mind that this was a very limited study onerning the effet of moisture.

92 CHAPTR 4. CONCLUSIONS AND RCOMMNDATIONS The onlusions and reommendations based on the findings of this investigation are summarized below. CONCLUSIONS General (1) The laboratory AVR design optimum asphalt ontents ranged from 3.5 perent to 4.5 perent for agle Lake gravel mixtures and from 6.6 perent to 7.3 perent for Lubbok limestone mixtures. Total air voids were affeted by both the soil binder ontent and the asphalt ontent. With proper asphalt ontent, the minimum total air voids ourred at soil binder ontents between 7 and 1 perent for agle Lake gravel mixtures and at 1 perent soil binder ontent for Lubbok limestone mixtures. The orresponding total air voids for Lubbok limestone mixtures with the laboratory AVR design optimum asphalt ontent were from 8.6 perent to 9. perent, whih were muh higher than those for agle Lake gravel mixtures (1.6 perent to 2.7 perent). (2) An optimum binder ontent for the maximum AVR density existed for the two materials. The agle Lake gravel mixture with 5 perent soil binder ontent had the lowest optimum asphalt ontent (3.5 perent) and the highest density (2,447 kg/m 3 ) while the Lubbok limestone mixture with 1 perent soil binder ontent had the lowest optimum asphalt ontent (6.5 perent) and the highest density (2,219 kg/m 3 ). (3) There was a tendeny for the optimum asphalt ontent to derease as the soil binder ontent dereased; however, when the mixture ontained little or no soil binder the optimum asphalt ontent inreased. 81

93 82 Stati Charateristis (1) Both agle Lake gravel and Lubbok limestone mixtures exhibited essentially equal maximum stati tensile strengths; however, the asphalt ontent required for the Lubbok limestone mixtures (6 perent) was muh higher than that for agle Lake gravel mixtures (3 perent). (2) Within the limits of this study, no definite relationship ould be found between stati modulus of elastiity and soil binder ontent for agle Lake gravel mixtures; however, an optimum soil binder ontent (1 perent) for maximum stati modulus of elastiity existed for Lubbok limestone mixtures. RepeatedLoad Charateristis (1) A definite optimum binder ontent for maximum fatigue life existed for both the agle Lake gravel and the Lubbok limestone mixtres. At the same stress level (1 kpa), the fatigue life of Lubbok limestone mixtures was muh higher than that of agle Lake gravel mixtures, i.e., the maximum fatigue life of Lubbok limestone mixtures at 5 perent binder ontent was about 11 times that of agle Lake gravel mixtures. (2) For resilient modulus of elastiity and stati modulus of elastiity no well defined optimum soil binder ontent existed for the agle Lake gravel mixture; however, an optimum soil binder ontent (1 perent) was found for the Lubbok limestone mixture. (3) For permanent deformation, an optimum soil binder ontent (5 perent) was found for the agle Lake gravel mixture. Although the data were insuffiient for the Lubbok limestone mixtures, the general tendeny indiated that an optimum soil binder ontent for minimum permanent deformation per yle existed somewhere around 5 perent. Moisture Damage (1) The moisture damage for the Lubbok limestone mixture was more severe than for the agle Lake gravel mixture. (2) The moisture damage appeared to be diretly related to the total air voids of the mixture, i.e., the damage due to water was greater for mixtures with higher total air voids.

94 83 Optimum Asphalt Content (1) Optimum asphalt ontents were found to our for the following material properties: (a) AVR density, (b) tensile strength, () stati modulus of elastiity, (d) fatigue life, and (e) permanent deformation. No welldefined optimum ourred for the resilient modulus of elastiity. (2) The optimum asphalt ontent for mixtures with higher soil binder ontent was generally larger than the optimum for mixtures with lower soil binder ontent. (3) In general, the lowest optimum asphalt ontent ourred at 5 perent soil binder for the agle Lake gravel mixture and at 1 perent soil binder for the Lubbok limestone mixture. Optimum Soil Binder Content (1) For the agle Lake gravel mixture, the optimum soil binder ontent was 5 perent for AVR density, tensile strength, fatigue life, and permanent deformation. (2) For the Lubbok limestone mixture, the optimum soil binder ontent ranged from 5 to 1 perent for the various engineering properties. RCOMMNDATIONS (1) A mixture design method whih is based on the indiret tensile test should be developed in the pavement design proedures. (2) Additional researh should be onduted to evaluate the effet of soil binder ontent for additional types of aggregate. (3) The adverse effets of moisture and its relationship with soil binder ontent should be investigated in more detail.

95 RFRNCS 1. Adedimi1a, Adedare S., and Thomas W. Kennedy, "Fatigue and Resilient Charateristis of Asphalt Mixtures by RepeatedLoad Indiret Tensile Test," Researh Report 1835, Center for Highway Researh, The University of Texas at Austin, August Anagnos, J. N., and T. W. Kennedy, "Pratial Method of Conduting the Indiret Tensile Test," Researh Report 981, Center for Highway Researh, The University of Texas at Austin, August Chastain, W.., and J.. Burke, "State Praties in the Use of Bituminous Conrete," Bulletin 16, Highway Researh Board, 1957, pp Campen, W. H., J. R. Smith, L. G. rikson, and L. R. Mertz, "The Control of Voids in Aggregates for Bituminous Paving Mixtures," AAPT Proeedings, Vol 26, Campen, W. H., J. R. Smith, L. G. rikson, and L. R. Mertz, "The Relationships Between Voids, Surfae Area, Film Thikness and Stability in Bi tuminous Paving Mixtures," AAPT Proeed ings, Vo 1 28, pps, Jon A., and Carl L. Monismith, "Influene of Mixture Variables on Flexural Fatigue Properties of Asphalt Conrete," Proeedings, Assoiation of Asphalt Paving Tehnologists, Vol 38, Fuller, W. B., and S.. Thompson, "The Laws of Proportioning Conrete," Transations, ASC, Vol 59, Goode, J. F., and L. A. Lufsey, "A New Graphial Chart for valuating Aggregate Gradations," Proeedings, AAPT, Vol 31, Hudson, S. B., and R. L. Davis, "Relationship of Aggregate Voidage to Gradation," Proeedings, AAPT, Vol 34, Hveem, F. N., "Gradation of Mineral Aggregates for Dense Graded Bituminous Mixtures," Proeedings, AAPT, Vol 11, Kennedy, Thomas W., and James N. Anagnos, "Proedures for Conduting the Stati and RepeatedLoad Indiret Tensile Test," Researh Report (in progress), Center for Highway Researh, The University of Texas at Austin. 12. Kennedy, Thomas W., and W. Ronald Hudson, "Appliation of the Indiret Tensile Test to Stabilized Materials," Highway Researh Reord No. 235, Highway Researh Board,

96 Khalifa, M.., and M. Herrin, "The Behavior of Asphalti Conrete Construted with LargeSized Aggregate," Proeedings, AAPT, Vol 39, Lee, D. Y., and R. N. Dutt, "valuation of GapGraded Asphalt Conrete Mixtures," Highway Researh Reord No. 361, Lees, G., "The Rational Design of Aggregate Gradings for Dense Asphalti Compositions," Proeedings, AAPT, Vol 39, Lottman, R. P., "Prediting MoistureIndued Damage to Asphalti Conrete," Final Report, NCHRP Projet 48(3), February Manual of Testing Proedures, Texas Highway Department, Vol 1, September MLeod, N. W., "Relationship between Density, Bitumen Content, and Voids Properties of Compated Bituminous Mixtures," Proeedings of the Highway Researh Hoard, Vol 35, MLeod, N. W., 'Void Requirements for DenseGraded Bituminous Paving Mixtures," ASTM Speial Tehnial Publiation No. 252, MCDowell, C., and A. W. Smith, ''Design, Control, and Interpretation of Tests for Bituminous Hot Mix Blak Base Mixtures," Texas State Department of Highways and Publi Transportation, TP869, Martin, J. P., "A Produer Views Plant Mixed Asphalti Conrete Base Courses," Proeedings, AAPT, Vol 3, ''Mix Design Methods for Asphalt Conrete and Other HotMix Types," The Asphalt Institute, Manual Series No.2 (MS2), Fourth dition, Marh Pell, p. S., and K.. Cooper, "The ffet of Testing and Mix Variables on the Fatigue Performane of Bituminous Materials," Proeedings, AAPT, Vol 44, Peters, David B., and Thomas W. Kennedy, "An valuation of the Texas Mix Design Criteria Using the Indiret Tensile Test," Researh Report 18311, Center for Highway Researh, The University of Texas at Austin, Rolled Asphalt (Hot Proess), British Standards Institution, London, B S. 594, Shmidt, R. J., "A Pratial Method for Measuring the Resilient Modulus of AsphaltTreated Mixes," Highway Researh Reord No. 44, Highway Researh Board, "Standard Speifiations for Road and Bridge Constrution," Texas State Department of Highways and Publi Transportation, Item No. 292, 1972.

97 Warden, W. B., and S. B. Hudson, "HotMixed Blak Base Constrution Using Natural Aggregate," Proeedings, AAPT, Vol 3, Winterkorn, H. F., "Granu1ometri and Volumetri Fators in Bituminous Soil Stabilization," Proeedings of the Highway Researh Board, Vo13, 1957.

98 APPNDIX A MIXTUR GRADATIONS