Thesis
Evaluation of recycled concrete for use as aggregates in new concrete pavements
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/100592
Abstract
The primary objective of this research is to determine if recycled concrete aggregate (RCA) sourced from demolished pavements in the central region of Washington State can be effectively utilized in new concrete pavements. The effects of two variables on concrete properties were evaluated in this study: the percentage of natural coarse aggregate replaced by RCA, and the incorporation of a 20% substitution of cement with Type F fly ash along with varying percentages of RCA replacement. Eight concrete batches were produced and a series of fresh and hardened concrete samples were created from each batch. The fresh concrete samples were tested for slump, air content, and density, and the hardened concrete samples were tested for compressive strength, modulus of rupture, and coefficient of thermal expansion. Tests were performed on the RCA to determine the absorption, specific gravity, Los Angeles abrasion loss, degradation value, and alkali-silica reactivity. Incorporating RCA into a concrete mix decreased the workability of the fresh concrete. In contrast, substituting fly ash increased the workability of fresh concrete and could be utilized to counter the slump reduction caused by the addition of RCA. A higher percentage of RCA v substitution correlated to a lower fresh concrete density. The percentage of RCA substitution did not have an influence on compressive strength, modulus of rupture, or coefficient of thermal expansion. All of the concrete mixes with RCA investigated in this study, including up to a 45% substitution of RCA, met all Washington State Department of Transportation (WSDOT) requirements for portland cement concrete pavements. The conclusions from this study indicate that coarse RCA can be suitable for use as an aggregate source for concrete pavements. Further, the restriction of 30% substitution of RCA recommended in previous studies may be overly restrictive. In order meet the WSDOT minimum degradation value for aggregates, it is recommended that the RCA be washed and fine materials removed prior to use.
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Details
- Title
- Evaluation of recycled concrete for use as aggregates in new concrete pavements
- Creators
- Daniel Gilbert Mjelde
- Contributors
- David I. McLean (Degree Supervisor)Haifang Wen (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525117701842
- Language
- English
- Resource Type
- Thesis