Pengembangan Beton Berpori Nano Green Engineering Berbasis Cangkang Kerang Dara dengan SiO2 Abu Boiler Kelapa Sawit dan Zeolit Alam Pahae

Abstract

This study aims to develop a nano green engineering porous concrete using blood cockle shells combined with SiO2 extracted from palm oil boiler ash (POBA) and Pahae natural zeolite as partial cement replacements. The goal is to enhance the mechanical and physical properties of porous concrete while utilizing Indonesia’s abundant natural resources. The SiO2 extraction process employed the coprecipitation method, and concrete production followed ACI 522R-10 standards using cylindrical samples (15 cm in diameter and 30 cm in height) with a 28-day curing period. Material characterization involved XRD, XRF, SEM-EDX, and PSA analyses, while coarse aggregates were tested for moisture content, silt content, and bulk density. Concrete properties evaluated included porosity, density, water absorption, compressive strength, and split tensile strength. XRD, XRF, and SEM-EDX results of blood cockle shells showed an average crystal size of 26.83 nm, a dominant CaO content of 75.94%, and a flaky–granular morphology dominated by Ca, O, and C elements, indicating CaCO3 presence. The extracted SiO2 from POBA exhibited an amorphous structure with a diffraction peak at 2θ ≈ 22°, a crystal size of 3.02 nm, and an increased SiO2 content to 99.31%. Silica from Pahae natural zeolite displayed a similar pattern with a crystal size of 3.52 nm and SiO2 content of 92.18%. The mixture with 5% cockle shell + 5% zeolite silica achieved the highest porosity and water absorption, while 5% cockle shell yielded the highest density and split tensile strength. The optimum compressive strength was found at 10% cockle shell substitution. These findings confirm the potential of the three materials as eco-efficient additives for sustainable porous concrete.