Mechanical Performance of Structural Concrete with the Incorporation of Coarse Recycled Concrete and Ceramic Aggregates

Abstract

The paper presents the results of an experimental program to evaluate the viability of concrete made when various ratios of coarse natural aggregates (CNAs) are replaced with coarse recycled concrete aggregates (CRCAs), coarse recycled ceramic masonry and mortar aggregates (CRMMAs), or both. Results show that incorporation of CRCA and of CRCA and CRMMA simultaneously has no effect on compressive strength. However, this property decreases when only CRMMA is incorporated. A reduction of 23.6% in compressive strength was obtained when 50% of CRMMA was used. Splitting tensile strength is unaffected by incorporation of CRCA but it is affected by incorporation of CRMMA. The mixes with 50% of CRMMA showed a reduction of 20.1% in tensile strength. Every recycled aggregate concrete type suffered a linear decrease of modulus of elasticity as the replacement ratio of CNA by coarse recycled aggregates increased. The use of 100% CRCA caused a decrease in modulus of elasticity of 30%. In the mixes with 50% of CRMMA that decrease was 22.2%. Shrinkage was significantly affected by incorporation of course recycled aggregates, although the degree of shrinkage varied in accordance with their nature and incorporation ratio. For replacement ratios between 50 and 100%, the difference between a reference concrete (RC) and the mixes with CRCA remained constant, inside a 30% increase range.