BEHAVIOR OF SOIL-CEMENT IN REPEATED COMPRESSION AND FLEXURE

RESULTS ARE PRESENTED OF AN INVESTIGATION OF THE BEHAVIOR OF SOIL-CEMENT SUBJECTED TO REPEATED LOADS OF SUBFAILURE MAGNITUDE IN BOTH COMPRESSION AND FLEXURE AND OF THE RESULTANT EFFECTS ON STRENGTH AND DEFORMATION PROPERTIES. THE DYNAMIC PROPERTIES, THE RESILIENCE CHARACTERISTICS, AND THE FATIGUE BEHAVIOR OF TWO TYPES OF SOIL-CEMENT / A SILTY CLAY AND A SAND/ UNDER THE ACTION OF BOTH REPEATED COMPRESSIVE AND FLEXURAL STRESSES WERE INVESTIGATED. THE CONCLUSIONS ARE SUMMARIZED AS FOLLOWS'/1/ UNDER CONSTANT REPEATED STRESS, THE MODULUS OF RESILIENT DEFORMATION IN BOTH COMPRESSION AND FLEXURE AT A GIVEN NUMBER OF LOAD APPLICATIONS IS DIRECTLY RELATED TO DRY DENSITY FOR ESM- CEMENT SAMPLES, /2/ THE MODULUS OF RESILIENT DEFORMATION OF SOIL-CEMENT IN REPEATED COMPRESSION IS GREATLY AFFECTED BY THE MAGNITUDE OF THE STRESS INTENSITY, /3/ RESULTS FROM THE REPEATED FLEXURE TESTS INDICATE THAT THE RESILIENT DEFORMATION REMAINS ALMOST UNCHANGED WITH RESPECT TO NUMBER OF LOAD APPLICATIONS, EVEN AT APPLIED STRESS INTENSITIES VERY CLOSE TO THE LIMITING VALUE WHICH CAUSES FATIGUE FAILURE, /4/ THE LONGER THE CURING PERIOD BEFORE THE START OF REPEATED COMPRESSION, THE GREATER THE MIMIMUM RESILIENT MODULUS FOR A REPEATED LOADING STRESS EQUAL TO A GIVEN PERCENTAGE OF THE INITIAL STRENGTH, /5/ SOAKED SAMPLES YIELD SMALLER VALUES OF RESILIENT MODULUS THAN UNSOAKED SAMPLES WHEN SUBJECTED TO THE SAME MAGNITUDE OF REPEATED LOADING STRESS, /6/ THE VALUES OF MODULUS OF RESILIENT DEFORMATION ARE SEVERAL TIMES GREATER IN COMPRESSION THAN IN FLEXURE, EXCEPT IN VSC-CEMENT SAMPLES COMPACTED WET OF OPTIMUM WHERE ESSENTIALLY THE SAME VALUES OF MODULUS ARE RECORDED IN BOTH TYPES OF TESTS, /7/ THE VALUES OF MODULUS OF RUPTURE RANGE FROM ONE-FOURTH TO ONE-HALF OF THE VALUES OF UNCONFINED COMPRESSIVE STRENGTH, /8/ THE STRAIN AT FAILURE IN FLEXURE IS ONLY ABOUT 5 TO 15 PERCENT OF THAT IN COMPRESSION, /9/ THE TANGENT MODULUS AS DETERMINED BY STATIC TESTS IS GREATER IN FLEXURE THAN IN COMPRESSION, /10/ THE MINIMUM STRESS INTENSITY REQUIRED TO CAUSE FATIGUE FAILURE IN VSC-CEMENT SAMPLES IS ABOUT 90 PERCENT OF THE STRENGTH OF THE SAMPLE BOTH IN COMPRESSION AND IN FLEXURE, WHEREAS IN ESM-CEMENT SAMPLES THE MINIMUM STRESS INTENSITY IS AROUND 75 PERCENT OF THE STRENGTH IN FLEXURE.