The production of neem products from neem tree generates large quantity of waste annually. There is need to reduce environmental pollution resulting from neem seed covering. Therefore, the use of Neem Seed Husk Ash (NSHA) as partial substitution for cement in concrete was investigated. Neem seed husk was obtained from Bishop Smith Memorial College, Ilorin, Nigeria; sundried for 3 days and then calcined at 650 o C. The calcined neem seed husk was ground and sieved using 200 μm sieve to obtain NSHA. Pozzolanicity test was conducted on NSHA to determine its chemical composition. Concrete was produced with 5, 10, 15, 20 and 25% by weight of NSHA substitution for ordinary Portland cement. Workability tests (slump and compacting factor) were performed on fresh concrete while compressive strength test was conducted on 150 mm cubes at ages 3, 7, 14, 21, 28, 56, 90 and 180 days for the hardened concrete. NSHA mainly comprises Al2O3, SiO2 and Fe2O3 with a combined percentage of 75.35%. The slump and compacting factors of NSHA concrete ranged from 5.50 mm to 10.00 mm and 0.91 to 0.95, respectively. The compressive strength at 180 days decreased from 26.9 N/mm 2 to 19.4 N/mm 2 as the NSHA content increased from 5% to 25%. Only 5% NSHA substitution is adequate to enjoy maximum benefit of strength gain.

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Effects of Water cement ratios on strengths characteristics of concrete produced with Recycled Iron and Steel Slag (RISS) aggregates was studied to understand the structural integrity of RISS aggregate in concrete and to determine the veracity of RISS aggregate as alternative aggregate to granite in concrete works. Mineralogical composition of the aggregate showed Silicon oxide (quartz) as the common mineral; both aggregates are well graded, strong and durable. Lower water cement ratios improved both the compressive and flexural strengths of RISS and granite concrete.

At present, the conventional sources for mineral filler in asphaltic concrete mixes are the chemical element of lime, cement, quarry dust and fly ash which has some health hazards. This study presents a laboratory investigation on the effects of locust bean ash as filler in Hot Mix Asphalt (HMA) production for a wearing course in order to find a cost-effective, environmentally friendly and less hazardous alternative to the traditional mineral filler of cement or lime. A total of 90 trials of bituminous mixtures with two types of mineral filler (locust bean ash and ordinary Portland cement) at 4 loading rates of 0, 2.5, 5 and 10% were evaluated for mechanical (strength) and workability performance properties according to standard asphalt mix Marshall Method of design. The Marshall stability, flow, density and void properties were developed for each mineral filler contents and the corresponding optimum binder content were determined for the general specification for roads and bridges in a subtropical region. The 2.5% for the two types of mineral filler was found to produce best performance of the HMA at optimum binder content of 5.5%. Also, the use of locust bean ash was found to be hazardous-free. Similarly, mineral filler from biomass was found to be advantageous for use as mineral filler source in asphalt mix production. Its application in the subtropical region where the biomass wastes are mostly abundant was recommended for HMA.

Neem tree (Azadirachtaindica) is a tropical evergreen tree scattered all over the country, hence its availability can add to the list of materials used as pozzolan. This study investigated the characteristics of Neem Seed Husk Ash (NSHA) blended cement produced in the factory. Neem fruit was collected from Olooru town and Ilorin metropolis in Kwara State Nigeria, after collection, the seed was removed with the use of Decorticator huskers, sun dried for 3 days to reduce its moisture content and burnt in a furnace at a temperature of 650 ± 50 oC. The chemical composition (SiO2, Al2O3 and Fe2O3) and physical characteristics were determined. Blended cement was produced by intergrinding 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by weight of NSHA with Ordinary Portland Cement (OPC) clinker and gypsum. OPC without NSHA served as the control. The blended cements produced were analyzed for chemical composition using X-Ray Flourescence Analyser (XRF). The physico-mechanical properties of blended cement (fineness, initial and final setting time, heat of hydration) produced was examined. The total percentage of SiO2, Al2O3 and Fe2O3 for NSHA is 75.35%. Factory produced NSHA – blended cement is suitable as it satisfied the maximum requirement of 375 minutes for final setting time and 45 minutes minimum initial setting time, hence it can be used for construction work where strength is not a priority