Influence of Polyester and Acrylic Polymer Coatings on the Mechanical, Physical and Microstructural Characteristics of Recycled Aggregate Concrete

This study investigated the potential of recycled concrete aggregate (RCA) as a sustainable alternative to natural aggregates. This aggregate was treated by coating it with two different polymeric materials: Acrylic and Polyester. This coating process aimed to enhance the properties of the RCA and improve the overall performance of the (A.RCA), and (P.RCA) mix. These coated aggregates were incorporated into concrete at replacement levels ranging from 25% to 100%. Four different combinations of A.RCA and P.RCA were used as substitutes for RCA as follows: 25%, 50%, 75%, and 100%. The slump flow was assessed for the fresh concrete, while the compressive strength, tensile strength, water absorption, and bulk density were examined for the hardened concrete. Also, microstructural properties of concrete were examined using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) techniques on concrete samples. Results demonstrated that polymer-coated RCA improved workability and density while maintaining acceptable water absorption levels. Acrylic-coated RCA significantly enhanced compressive strength, particularly at 75% replacement, due to improved aggregate-cement bonding. Tensile strength was also enhanced with acrylic-coated RCA. Microstructural analysis revealed that acrylic-coated RCA promoted C-S-H formation and a refined interfacial transition zone, contributing to improved concrete performance.