Production and Strength Evaluation of Sandcrete Hollow Blocks Using Fine sand and Crushed Periwinkle shell

Abstract

Walls are fundamental in building construction, with sandcrete blocks being the most common unit in Nigeria. Sandcrete blocks are made of natural sand, water, and cement. Due to rising material costs, importation issues, and sub-standard materials that do not meet quality specifications in terms of strength, durability, or composition, there is a need to find cost-effective alternatives. This research explores using Crushed Periwinkle Shell (CPWS) to partially replace fine sand. A 1:12 mix ratio was chosen for its cost-effectiveness and suitability for non-load bearing applications. This mix was tested with 0%, 10%, 20%, 30%, 40%, and 50% CPWS, maintaining a constant water-cement ratio of 0.5. Ninety blocks (450mm x 225mm x 150mm) were molded and cured for 28 days. The compressive strength of seventy-two blocks was evaluated at 7, 14, 21, and 28 days. Blocks with 40% and 50% CPWS had high compressive strength values of 2.55 N/mm² and 2.67 N/mm² at 28 days, within the Nigeria Industrial Standard (NIS) range of 2.5-3.4 N/mm². These results suggest CPWS is suitable for partial sand replacement. Additionally, eighteen blocks were tested for water absorption at 14, 21, and 28 days, showing increased absorption with higher CPWS content but decreasing with curing time.

Keywords

• sandcrete blocks, periwinkle shell, compressive strength, building construction, water absorption