• 2025-04-25
• O.A. Akintulaji
• Volume 1, Issue 1

Abstract

Building failures in developing countries result from the use of cement-stablised blocks with low compressive strength due to minimal cement use. Affordable vibrating and slam-shut machines cannot produce high-strength blocks with low cement, while hydraulic machines, though efficient, are too costly for small-scale use. This study evaluates a motorized impact moulding machine, which applies a dynamic compaction technique to minimise cement use by delivering repeated impact blows from a falling ram to densify the block. Blocks (450 × 225 × 225 mm) were produced at three cement levels (5%, 8%, and 10%) and two compaction ratios (1.3:1 and 1.5:1), and their compressive strengths were compared with blocks produced by vibrating and slam-shut machines. Analysing the data statistically revealed significant effects of machine type and cement level (p < 0.0001), with the impact moulding machine consistently producing stronger blocks, especially at a 1.5:1 compaction ratio and 8% and 10% cement levels. Among the blocks tested, only solid soilcrete (2.60 N/mm²) and sandcrete (3.00 N/mm²) blocks at 10% cement and 1.5:1 compaction met the NIS 87 (2004) minimum requirement of 2.5 N/mm². The motorized impact moulding machine proved effective in producing cost-efficient blocks of high compressive strength with reduced cement content.