ENHANCING THE COMPRESSIVE STRENGTH OF SANDCRETE BLOCKS THROUGH IMPROVED SAND GRADING: A CASE STUDY OF EROSION SAND FROM EKPOMA

Abstract

This study investigates the suitability of locally sourced erosion sand from Ekpoma, Edo State, Nigeria, for the production of sandcrete solid blocks, with emphasis on the effect of sand grading and stabilization (particle size distribution improvement) on block density and compressive strength. In this study, sand stabilization refers to grading correction through sieving and the addition of deficient particle sizes to achieve a well-graded aggregate; it does not imply chemical stabilization. Sand samples were collected from three locations—Ambrose Alli University Campus, Ujemen, and Ihumudumu—and subjected to sieve analysis to determine their particle size distribution characteristics. Sandcrete blocks were produced using three aggregate conditions: untreated erosion sand, stabilized (sieved and grading-improved) erosion sand, and conventional riverbed sand as a control. All blocks were cast using a 1:6 cement–sand mix ratio and cured under laboratory conditions. Compressive strength tests were conducted at 7, 14, 21, and 28 days, while density and moisture content were also determined. Results indicate that stabilized erosion sand produced blocks with higher density (up to 1807 kg/m³) and improved compressive strength (up to 2.86 N/mm²), comparable to blocks produced with riverbed sand. The findings demonstrate that poorly graded local erosion sand can be effectively improved through grading correction for sandcrete block production. This provides a cost-effective and environmentally sustainable alternative to riverbed sand, with significant implications for low-cost housing and resource optimization in Nigeria.

Keywords: Erosion sand, Sandcrete blocks, Compressive strength, Density, Sieving, Local building materials