Date Approved

1-3-2022

Embargo Period

1-4-2022

Document Type

Thesis

Degree Name

M.S. Civil Engineering

Department

Civil and Environmental Engineering

College

Henry M. Rowan College of Engineering

Advisor

Gilson R. Lomboy, D.Eng., Ph.D.

Committee Member 1

Douglas B. Cleary, Ph.D., P.E.

Committee Member 2

Cheng Zhu, Ph.D.

Keywords

Abrasion, Absorption, Durability, Recycled Concrete Aggregates (RCA), Regression model, Resistivity

Subject(s)

Concrete; Recycling

Disciplines

Civil Engineering

Abstract

The supplies of concrete aggregates from natural sources are rapidly reducing. Recycled concrete aggregates (RCA) are produced by crushing the concrete obtained from demolished concrete structures. The purpose of this study is to determine the durability properties of concrete with 100% recycled concrete coarse aggregates and relate the durability of such concrete to the physical, mechanical, and durability properties of RCA and the RCA parent concrete. The correlations of several properties are determined by developing model equations to predict RCA properties. The parent concrete is crushed and graded at two nominal maximum sizes, 1" and 0.75", to determine the RCA production effects on new concrete. Six varieties of RCA were manufactured for the study. Concrete mixtures with RCA coarse aggregate have water-to-cement ratios of 0.38 and 0.48. Physical properties of aggregates tested in the lab include bulk density, specific gravity, absorption, and residual mortar. The concrete durability is obtained by measurement of resistance to degradation, resistivity test, density, absorption, and voids in the hardened concrete. A regression model for the surface resistivity of RCA showed that the surface resistivity increases when the absorption of RCA, w/c of concrete, and the volume of mortar decrease. The research results contribute to increasing RCA use through an improved understanding of its influence on concrete durability.

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