Date of Award

2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Choi, Wonchang Dr.

Abstract

The objective of this study is to evaluate the feasibility of using concrete containing Recycled Concrete Aggregate (RCA) and Fly Ash in concrete pavement applications. The use of RCA and fly ash in concrete pavement applications has not been fully developed. The advantage to use both RCA and fly ash can improve workability and durability, due to properties of RCA and fly ash, as well as environmental protection and sustainability of material sources. RCA in concrete is less susceptible to durability problem because the aggregates have already endured the majority of the damage. By adding fly ash to increase workability without increasing the water content improve the durability of the resultant pavement. This research consisted of two batches of different concrete mixtures produced in the laboratory. The first batch of concrete contained 0%, 25% of RCA with 0%, 10%, and 15% fly ash (by weight) was cured with two cure durations with a w/c ratio of 0.55. The second batch of concrete mixture contained the same amounts of RCA and fly ash as aforementioned with w/c ratio of 0.45. The effects of RCA and fly ash on the compressive strength, modulus of electricity, and flexural strength are discussed in this research with a target compressive strength of 4500psi, and 5500psi at water/cement ratios of 0.5, and 0.4 of referenced control mix, respectively. The resulting data indicates that the mix containing 10%, 15% fly ash and 25% RCA slightly reduced the strength but is still comparable with the concrete containing virgin xiv aggregate without fly ash. With the use of RCA up to 25%, and fly ash up to 15%, there will not be a significant difference (if any) in strength compared with concrete containing virgin aggregate and Type I, Portland cement. Therefore the assertion of great benefits to using recycled aggregate as a substitute for virgin aggregate, and using fly ash (a byproduct from coal burning) as a cement replacement for concrete pavement remains valid.

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