STRENGTH CHARACTERISTICS OF FINE AGGREGATE MIXED WITH LATERITE CONTENT IN SANDCRETE BLOCK PRODUCTION

The increase in demand of construction materials in Nigeria has made project work extensively on the need to incorporate locally materials into production of sand hollow blocks. This project investigate the strength water absorption of sandcrete blocks mixed with laterite as a partial replacement of sharp sand at 5%, 15% and 25% respectively. A total of thirty – two (32) hollow blocks were produced with the block molding machine with a steel mould of 450mm x 220mm x 150mm were subjected to compressive strength test of 7 and 28 days curing and water absorption tests was also assessed at immersion duration of 30 minutes, 1 hour, 3 hours, 24 hours and 48 hours. Result showed that compressive strengths of 1.89N/mm² at 7 days and 2.60N/mm² at 28 days, meeting the Nigerian industrial standard (NIS, 2007) requirements of 1.8N/mm² and 2.5N/mm², respectively. However, blocks with 5%,15%, and 25%laterite failed to meet the minimum NIS strength at both 7 and 28 days. In term of durability, water absorption increased with immersion time and higher laterite content. The 15% replacement exhibited the highest absorption of 2.72% at 48 hours, compared to 2.45% for the control. These findings indicate that laterite substitution reduces both strength and resistance to water absorption, with only the control mix fully satisfying the NIS (2007) standard for sandcrete blocks. The Atterberg limit test indicated a liquid limit of 21.7%, a plastic limit of 17.1%, and a plasticity index of 4.6%, with 24% passing the No. 200 sieve. The soil was classified as A-2-6 under the AASHTO system, representing silty or clayey gravel and sand with low to medium plasticity. The result suggest that the soil possesses good engineering properties, low susceptibility to swelling and suitable for use in subgrade and subbase layer in pavement construction. Compressive strength values decrease with increasing laterite content, with the control mix outperforming all replacement. Nevertheless, the 28 days strength result of all mixes remained within the acceptable limits for non-load bearing sandcrete blocks. Water absorption increased with time and laterite content, indicating that laterite rich blocks are more porous and less durable under prolonged moisture exposure. An optimal performance balance was observed at low laterite replacement level (not exceeding 10-15%).