Chemical Modifications of Recycled Concrete Aggregate

Abstract

The necessity for environmental sustainability has prompted the utilization of recycled concrete aggregates (RCA) sourced from structural demolition sites for the production of recycled aggregate concrete (RAC). The primary element impacting the quality of recycled concrete aggregate (RCA) is the mortar paste that adheres to the natural aggregate (NA). The cement mortar adhered to recycled concrete aggregate exhibits higher porosity and water absorption levels, along with reduced strength compared to natural aggregate. These characteristics negatively impact both the mechanical properties and durability of fresh and hardened concrete incorporating recycled concrete aggregate. As a result, it is crucial to enhance the interface by improving the surface of the aggregate or by removing the mortar adhered to the NA. Methods for achieving this include surface modification of the aggregate or removing adhered paste from the natural aggregate (NA). This research includes treatment involving acidic solutions particularly hydrochloric acid (HCl), and sulphuric acid (H2SO4), for mortar layer removal from RCA, analyzing their impact on the mechanical properties of aggregates and durability of concrete incorporating RCA.