Dissertation/Thesis Abstract

Ground tire rubber as a component material in concrete mixtures for paving concrete
by Twumasi-Boakye, Richard, M.S., The Florida State University, 2014, 114; 1565796
Abstract (Summary)

The management of solid waste is a major environmental concern in the United States. Waste tire rubber forms a major part of this problem and a rather severe one since tire rubbers are not biodegradable hence its disposal into landfills are of great concern. This research primarily focused on finding the best way of producing paving concrete with the use of ground tire rubber as a component material.

Tests on rubber concrete were performed in two stages. Preliminary tests were performed using both 40-mesh GTR and 3/8-inch rubber chips (RC) to replace fine aggregates and coarse aggregates respectively by weight in the concrete mix. This stage of testing considered zero to 40 percent GTR replacement of fine aggregates by weight at 10 percent increment and for zero to 30 percent RC replacement of coarse aggregates by weight at 10 percent increment. Observations from this stage guided the formulation of a second and final stage of testing which involved only zero to 20 percent GTR replacement of fine aggregate by weight at 5 percent increment. The mix design for this stage involved the use of water reducers, air-entrainer and fly-ash. In addition to concrete mechanical property tests, coefficient of thermal expansion (CTE), plastic shrinkage and drying (free) shrinkage tests were also conducted.

Results from preliminary tests indicated that GTR and RC concrete specimens were of relatively low strength, improved toughness and showed more elasticity when compared to normal concrete specimens. The final stage of laboratory testing however showed improved strength characteristics, with the initial observations of improved toughness and low modulus of elasticity still evident. Coefficient of thermal expansion (CTE) test results did not show significant difference between mix-types, with the range of results falling within the typical limit for normal concrete. Plastic shrinkage test results showed that the inclusion of GTR helped in reducing plastic shrinkage cracks in concrete. Preliminary results at the second stage testing on drying shrinkage using 10% GTR concrete indicated a reduction in free shrinkage when compared to the control specimens.

Indexing (document details)
Advisor: Sobanjo, John O.
Commitee: Spainhour, Lisa, Tawfiq, Kamal
School: The Florida State University
Department: Civil and Environmental Engineering
School Location: United States -- Florida
Source: MAI 53/06M(E), Masters Abstracts International
Subjects: Civil engineering
Keywords: Coefficient of thermal expansion, Drying shrinkage, Ground tire rubber (gtr), Modulus of elasticity, Paving concrete, Plastic shrinkage
Publication Number: 1565796
ISBN: 978-1-321-21579-3
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