http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Rheology of crumb rubber modified asphalt binders and mixes
xiii, 171 leaves : illustrations ; 28 cm.
Laboratory test procedures are presented to determine the rheological properties of crumb robber modified asphalt (CRMA) binders and mixes. These tests provide simple, fast, and cost-effective alternatives to evaluate the performance (rotting and cracking potential) of binders and mixes used for pavement construction. Viscoelastic properties of CRMA binders are measured using dynamic shear analysis. Master curves were generated using the principle of time-temperature superposition to evaluate the effects of aging, robber concentration, and curing conditions on the rheology of the modified binder. Results indicate that the rheology of CRMA binders can be divided into three regions of viscoelasticity: glassy region at high frequencies, transition/viscoelastic region at intermediate frequencies, and viscous region at low frequencies. Modification of the asphalt by addition of rubber leads to an improvement in both the high and low temperature properties, as reflected by changes in G' and G", which causes the binder to have a greater resistance to specific pavement failure mechanisms. Both transient and dynamic properties of CRMA mixes were measured in the laboratory using the creep and recovery, direct tension, and frequency sweep tests.Rheological properties of the mix generated from the test data were compared to those of the binder to evaluate the effect of aging, rubber concentration, and curing conditions on mix performance. Several rheological parameters have been identified to characterize the rutting and cracking potential of mixes. A power law equation was found to give good correlations between several mix rheological parameters. Analysis of binder and mix failure energies show that work of cohesion of the binder is negligible compared to the failure energies. A unique relationship between Paris law material parameters has been confirmed. It is also shown that mix failure properties bear a one-to-one correlation with binder failure properties. Based on the results of this work, it is concluded that modification of asphalt by rubber produces a rheologically superior binder. This modified binder can be successfully used to fabricate laboratory mixes that exhibit better resistance to several failure mechanisms. CRMA binders should therefore be seriously considered as a cost-effective alternative for pavement construction.
Issued also on microfiche from University Microfilms Inc.
Includes bibliographical references: pages 164-170.