Assessment of the Quality of Workmanship in Sandcrete Block Production in Benue State

Sandcrete blocks are the dominant walling unit in Nigerian residential construction, and the quality of workmanship in their production directly affects structural safety. This study assessed the quality of workmanship in sandcrete block production by artisan block makers in Makurdi, Otukpo, and Gboko Local Government Areas of Benue State, North Central Nigeria. A laboratory-based field study was conducted, with 180 sandcrete block samples (6-inch hollow blocks) collected from 30 block production sites. Blocks were tested for compressive strength, water absorption, and dimensional accuracy per NIS 87:2004. Site surveys assessed mix ratio practices, curing procedures, and production equipment used. Results showed that only 34% of sampled blocks met the minimum compressive strength of 3.45 N/mm2 specified by NIS 87:2004 for load-bearing applications. Water absorption exceeded the maximum of 12% by weight in 61% of samples. Dimensional tolerances were within acceptable limits in 72% of blocks. The most common mix ratio used by artisans (1:10, cement:sand) was significantly leaner than the recommended 1:6, explaining the high rate of substandard strength. Curing was inadequate (below 7 days) at 77% of sites. The study concludes that sandcrete block quality in Benue State is critically inadequate and poses structural risks. Mandatory market certification and periodic quality inspection of block production sites by the Benue State Ministry of Housing are recommended.

Keywords: sandcrete blocks, compressive strength, workmanship quality, Benue State, NIS 87:2004