Analisis Microstructure pada Perkerasan Komposit - Kerikil Aspal Berbasis Mortar dan Crumb Rubber (CR) - ECC

Abstract

This study investigates the microstructure of composite asphalt aggregate pavement modified with mortar and crumb rubber-based Engineered Cementitious Composites (ECC). The objective is to identify the microstructural characteristics of the composite materials and their correlation with mechanical properties (compressive strength) and fire resistance. An experimental approach was employed, incorporating XRF, XRD, FTIR, and SEM–EDX Mapping analyses on cement, palm shell ash (PSA), mortar ECC, crumb rubber ECC, and composite pavement samples subjected to compressive strength and fire resistance testing. XRF results indicated that PSA contained a high level of amorphous silica (42.9%), which reacted to form C–S–H gel, resulting in a highly dense mortar ECC matrix at a 10% PSA replacement. Conversely, the addition of crumb rubber increased interfacial porosity, thereby reducing compressive strength. XRD confirmed the dominance of amorphous phases in PSA that facilitate C–S–H formation. FTIR detected Si–O–Si bonds and portlandite in both PSA and ECC mortar, reinforcing evidence of hydration and gel development. SEM–EDX Mapping revealed that the composite pavement structure comprised asphalt aggregate layers bound by a dense ECC matrix, with interfacial zones in mortar ECC–based samples being more compact than those in crumb rubber ECC–based samples, which were more porous. Fire resistance testing showed that up to 500 °C, the materials remained largely intact with limited damage, and the crumb rubber–mortar ECC composite exhibited the best fire resistance due to the combination of dense C–S–H networks and a protective carbon layer formed from crumb rubber combustion. Scientifically, this research fills a gap in the literature on microstructural analysis of ECC-based asphalt aggregate composite pavements and supports the advancement of sustainable construction technologies.