Assessment of Quality and Compliance of Commercially Produced Sandcrete Blocks in Kaduna Metropolis

Abstract

The rapid implementation of educational and administrative facility infrastructure at the Air Force Institute of Technology (AFIT), Kaduna, demands strict quality control of basic building components to mitigate risks of structural defects. This study evaluates the physical and mechanical properties of 225mm hollow sandcrete blocks supplied by five commercial block manufacturing yards (Industries A, B, C, D, and E) directly feeding structural partition works across the campus footprint. The engineering investigation comprised extensive field audits alongside laboratory characterization of aggregate particle size distribution curves, silt content percentages, dry bulk density properties, 24-hour volumetric water absorption capacity, and 28-day ultimate crushing test using a Compression Testing Machine (CTM) evaluated on both gross and net area bases. Experimental results demonstrated low  compliance margin against the statutory requirements of the Nigerian Industrial Standard (NIS 87:2007), which mandates a minimum gross compressive strength threshold of 2.5N/mm² for non-load bearing units. Industry E logged the highest structural capacity with an ultimate mean compressive limit of 1.497 ± 0.112N/mm² (gross area) and 2.495 ± 0.187N/mm² (net area), dry bulk packing density of 1611.36 ± 18.42kg/m³, and a minimized water absorption value of 7.03 ± 0.35%. Conversely, Industry C established the minimum structural baseline with a gross strength profile of 0.933 ± 0.084N/mm² and density configuration of 1532.86 ± 22.15kg/m³.Low structural compliance may be traced to commercial field malpractices including weak cement batching patterns (ranging from 1:12 to 1:16 variations), erratic water-cement ratios, excessive silt content in sand supplies, and inadequate on-site curing. Continuous quality audits and enforced standardization are critical to safeguard institutional infrastructural lifespans.