THE STUDY OF CONCRETE BEHAVIOUR PREPARED WITH CHEMICALLY TREATED RECYCLE AGGREGATE: A REVIEW

Abstract

The recycling of Construction and Demolition Wastes has long been accepted to have the possible to conserve natural resources and to decrease energy used in production. In some nations it is a standard substitute for both construction and maintenance, particularly where there is a scarcity of construction aggregate. The use of recycled aggregate weakens the quality of recycled aggregate concrete which limits its application. For improving the quality of recycled coarse aggregate, various surface treatment methods such as removing the attached mortar by ultrasonic cleaning method , ball milling , heating, and then rubbing or pre soaking RCAs with HCl, H2SO4, and H3PO4 ,improving the quality of attached paste, such as surface coating with water glass pozzolanic materials , or polyvinyl alcohol emulsion. However, the addition of acidic solvents can lead to new pollution, use of water glass increases the risk of alkali aggregate reaction, and the other methods require extra energy thus carbonation process is more adequate to be used .Strength properties of the treated and untreated coarse aggregate were compared. The results indicated that the compressive, flexure and split tensile strength of recycle aggregate is found to be less than the natural aggregate if used without treatment.