In an attempt to reuse and convert agro wastes into useful materials for the construction industry, this research considered the application of corn stalk ash (CSA) as partial replacement for ordinary Portland cement (OPC) in the production of interlocking paving stones. The study investigated the oxide composition of CSA to ascertain its suitability as a pozzolanic material. Some properties of paving stones with CSA as a replacement for OPC were examined. The results showed that CSA is a good pozzolana having satisfied the required standards. The compressive strength of the specimens with replacement levels ranging from 5 to 25% cured for periods of 3–56 days was lower at early curing time but improved significantly at later age. 10% replacement level showed increased strength compared to 0% CSA at 28 days curing period. Density decreased with increasing ash content, water absorption rate increased with increased CSA contents, while abrasion resistance increased with increasing amount of CSA substitutions. The test results revealed that CSA paving stones can attain higher strength than the conventional ones at longer curing periods, due to its pozzolanic reactions.

As a way of converting agro-wastes into useful materials for the construction industry, this research considered the application of corn husk ash (CHA) as partial replacement for ordinary Portland cement (OPC) in the production of interlocking paving stones. The study investigated the oxide composition of CHA to ascertain its suitability as a pozzolanic material. Some properties of paving stones with CHA as a replacement for OPC were evaluated. The results showed that CHA is a good pozzolana having satisfied the required standards. The compressive strength of the specimens, with replacement levels ranging from 5 to 25% cured for periods of 3-56 days, was lower at early curing age but improved significantly at later age. Five percent (5%) replacement level showed increased strength compared to 0% CHA regardless of curing age. Density decreased with increasing CHA content, water absorption increased with CHA content, while abrasion resistance decreased with CHA substitution. The test results revealed that CHA paving stones at 5% replacement can attain higher strength than the conventional ones at longer curing periods due to its pozzolanic characteristics.

Engineers are faced with the problems of providing very suitable materials for highway and other foundations construction. Lateritic soils are highly weathered indigenous soil available in large quantities but generally need improvements to adequately satisfy the required construction purposes. This research investigates the influence of steel slag and marble dust addition on some geotechnical properties of lateritic soil. The results revealed that the soil is well graded based on particle size distribution and is classified as A-2-5 under AASHTO system. With progressive increase in each stabiliser, both the liquid limit, plastic limit and plasticity index exhibit fluctuating patterns. In addition, both marble dust and steel slag increased the maximum dry density with increasing proportions in the soil sample but exhibit irregular patterns for optimum moisture content. This research provides an insight to the quality of lateritic soils obtainable in the study area, and the level of improvements required before they are suitable for road construction.

Effect of glass fines and cement as a composite mixture on the geotechnical properties of a poor lateritic soil obtained from a borrow pit at Aroje, Ogbomoso, Nigeria was investigated as a reuse method of managing wasted glass. Glass fines up to 12% at intervals of 4% by mass of the soil sample were added to the lateritic soil stabilized with cement of 0, 2, 4, and 6% by mass of the soil sample. Sieve analysis, Atterberg limit, British Standard (BS) Compaction, California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests were conducted on the stabilized soil specimens. Results showed that Liquid Limit (LL), Plastic Limit (PL) and Plasticity Index (PI) decreased while compaction and UCS of the lateritic soil increased from 0 to 8% addition of glass fines. The CBR of the soil increased continuously from 0 to 12% glass contents. However, addition of cement increased the LL and PI while it decreased the PL between 0 and 4% but increased beyond this range. The compaction, UCS and CBR of the stabilized soil increased significantly with increasing cement content. Hence, the soil can be stabilized with the addition of 8% glass fines and 6% cement content to be used as improved subgrade material for construction of light trafficked pavement.

Steel is produced from iron ore and purification of metal scrap, leading to manufacture of hundreds of tonnes of steel slag each year. This study investigated the optimum replacement of granite with Ife Iron and Steel Nigeria Limited (ISN) slag that produce maximum Compressive Strength (CS), Split Tensile Strength (STS) and Flexural Strength (FS) of concrete using Response Surface Methodology (RSM) from Design Expert Version 7.0. The outcome of the study showed that the optimum replacement of granite with ISN was 28.85% ISN at 0.47 W/C.