Immediate and time dependent compression of tire derived aggregate

Journal of Geotechnical and Geoenvironmental Engineering, 133(3): pp. 245-256.This paper examines immediate and time-dependent compression of tire derived aggregate (TDA)and TDA-soil composites. To accommodate large particle sizes, modified experimental devices were developed and used to test tire chips and tire shreds. Immediate compression of TDA, which results almost entirely from the reduction of pore volume, increases with TDA content and tire particle size. The secant constrained modulus (Msec ) of TDA defined over the stress range of 0–50 kPa varied from a low of 255 kPa (100% tire shreds )to a high of 1,320 kPa (50% tire chips). A characteristic relationship between strain and time exists for TDA and TDA composites under one-dimensional confined compression. Time-dependent deformation is well described by the modified secondary compression index (Cae) which ranged from 0.0010 (50% tire chips) to 0.0074 (100% tire chips). Time-dependent deformation was inversely proportional to sand content, with the most significant changes resulting from the addition of 15% sand. Both applied stress and tire particle size appear to have a negligible effect on time-dependent compression of TDA. Based on the findings of this study it is recommended that practitioners assess time-dependent settlement when designing a TDA structure and if necessary incorporate design features to accommodate these settlements

Variability and scale-dependency of tire derived aggregate

Journal of Materials in Civil Engineering, 19(3): pp. 233-241.This paper presents a variability study of several engineering properties of tire-derived aggregate based on a comprehensive literature survey of experimental test programs. The dry compacted unit weight, cohesion intercept, friction angle, constrained modulus, and modified secondary compression index were evaluated and compared to the engineering parameter variability of natural soils. A series of regression analyses were performed to investigate the presence and significance of scale-dependency. The results of the variability analysis indicate that unit weight has the lowest value of coefficient of variation COV whereas the shear strength parameters, constrained modulus, and compression index have COV values that are substantially higher. Regression analyses indicated that unit weight and constrained modulus showed the greatest sensitivity to changes in maximum tire particle size. A nonstatistical investigation was used to further investigate the variability and scale-dependency of the shear strength parameters. Using Mohr-Coulomb failure criterion and assuming that cohesion is negligible, the analysis showed a scale-independent relationship which is consistent with the statistical findings for cohesion and friction angle

Submicron Structures Fabrication and Research

Contains reports on thirteen research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0908)National Science Foundation (Grant ECS82-05701)I.B.M. (PO No. 90305-QPSA-559)U.S. Department of Energy (Contract DE-AC02-82-ER13019)Lawrence Livermore Laboratory (Contract 2069209

Submicron Structures Fabrication and Research

Contains reports on twelve research projects.Lawrence Livermore Laboratory (Subcontract 2069209)Joint Services Electronics Program (Contract DAAG29-C-0104)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0908)Joint Services Electronics Program (Contract DAAG29-80-C-0104)Harkness FoundationI.B.M.U.S. Department of Energy (Contract DE-ACO2-80-E10179)National Science Foundation (Grant ECS80-17705

Submicron Structures Technology and Research

Contains reports on thirteen research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0908)National Science Foundation (Contract ECS82-05701)U.S. Department of Energy (Contract DE-ACO2-82-ER-13019)Lawrence Livermore Laboratory (Contract 2069209)National Aeronautics and Space Administration (Contract NGL-22-009-638)U.S. Navy - Office of Naval Research (Contract N00014-84-K-0073)National Science Foundation (Grant ECS80-17705)National Science Foundation (Grant ENG79-09980