The Effect of Ale-Ale Shell Powder on the Compressive Strength and Water Absorption of Paving Blocks

Abstract

Ketapang Regency is widely known for its ale-ale clam (Meretrix sp.) commodity, yet high consumption rates generate a massive amount of hard shell waste that remains underutilized and pollutes the environment. Concurrently, conventional paving block production continuously exploits natural fine aggregates on a massive scale. This experimental study aims to analyze the effect of utilizing ale-ale shell waste as a partial substitution for fine aggregate on the compressive strength and water absorption characteristics of paving blocks based on the SNI 03-0691-1996 standard. The reference mixture proportion used was 1 Cement : 4 Sand (by volume) with variation rates of ale-ale shell substitution at 0% (normal), 5% (Variation I), 10% (Variation II), and 15% (Variation III). A total of 48 samples were tested to evaluate the compressive strength at 7, 14, and 28 days, as well as water absorption at 28 days. The results indicated that the optimum compressive strength growth was achieved by Variation II (10% ale-ale shell), reaching 17.23 MPa at 28 days, which significantly increased compared to the normal sample at only 14.06 MPa. Conversely, increasing the shell content to 15% in Variation III drastically reduced the compressive strength to 10.78 MPa. In terms of physical testing, Variation II (10%) recorded the lowest and most dense water absorption percentage of 9.83%. The water absorption characteristics of other variations exceeded the threshold, measuring at 10.32% (normal), 10.75% (Variation I), and 11.26% (Variation III). Based on the SNI 03-0691-1996 specification, only Variation II (10%) was declared to satisfy all physical and mechanical feasibility parameters for Grade D paving block classification (non-structural/garden).