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RECYCLING CONCRETE: A POSSIBLE APPROACH TO IMPROVE THE ENVIRONMENT

Dr. Akmal Abdelfatah
Assistant Professor, Civil Engineering Department, College of Engineering,
American University of Sharjah, P.O. Box 26666,Sharjah, UAE
Phone: (971-6)515-2903, Fax: (971-6)515-2979
Email: Akmal[at]aus.edu

Dr. Sami W. Tabsh
Professor and Head of the Civil Engineering Department, College of Engineering,
American University of Sharjah, P.O. Box 26666,Sharjah, UAE
Phone: (971-6)515-2957, Fax: (971-6)515-2979
Email: stabsh[at]aus.edu

Abstract

Many structures in the GCC countries are currently either reaching the end of their design life or were not constructed according to the specifications. This results in huge amount of concrete rubbles that are routinely discarded in landfill sites. Therefore, it makes economic and environmental sense to seek alternative means of disposal of concrete from construction and demolition operations. Hardened concrete can be reclaimed during demolition and crushed into coarse aggregate that can be used as a substitute for crushed natural rock. The objective of this study is to determine the mechanical of recycled concrete. To achieve the objective, laboratory tests are carried out on concrete specimens made from recycled concrete aggregate following the relevant ASTM standards. The variables that are considered in the tests include the properties of the recycled aggregates, percentage of recycled aggregates in the concrete mix, source of the recycled concrete, and target concrete strength. The recycled concrete specimen tests include compressive and tensile strengths, as well as water absorption. In general, the strength of recycled concrete can be 10–25% lower than that of conventional concrete. The main reason for this decrease in strength is due to the additional amount of water needed to achieve the same slump. The drop in strength in the recycled concrete can be avoided if chemical additives are used to increase workability instead of adding more water.

Application for Participation (PDF)