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This study evaluates the physical, mechanical and in-situ properties of the rock aggregates in Kajuru, Kaduna State, Nigeria as sources of aggregate for construction purpose. The uniaxial compressive strength was determined by using Universal Testing Machine to crush cored samples and Schmidt rebound number by Schmidt hammer apparatus. While the engineering destructive tests were carried out on aggregates using various apparatus. Na 2 SO 4 solution was used for soundness test and glass jar for determination of specific gravity. The results indicate that specific gravity ranges from 2.48 to 2.88, the moisture content of samples are within 2%. The UCS ranges from 95.76Mpa to 169.70Mpa while the Schmidt rebound number ranges from 29.4 to 35.3. Comparing the Los Angeles abrasion, impact and crushing value obtained from the laboratory destructive test with the B.S standards, most of the rock can be used for construction works. The results also indicate that there is direct proportional relationship between compressive strength with Schmidt rebound number and specific gravity. Inverse relationship exists between moisture content with specific gravity and compressive strength. The physical and geotechnical properties were found to be dependent on the chemical and petrographic characteristics of the rock.

The world is now focusing on a sustainable environment and reducing the effects of global warming. One way to achieve such targets is to properly utilize waste and reduce greenhouse CO2 emissions. The cement industry is responsible for almost 10% of global CO2 emission due to the high demand for cement in the construction industry. One of the ways to minimize this effect is the partial replacement of cement by other materials in concrete. Therefore, in this study, calcium carbide residue (CCR), which is highly rich in calcium oxide, partially replaced cement for waste management. Waste tires were grinded to fine sizes in crumb rubber (CR) and partially replaced the fine aggregate. Therefore, this paper investigared the influence of CR and CCR on the durability properties and heat/temperature resistance of self-compacting concrete (SCC). The experiment was designed using response surface methodology to investigate the effects of CR and CCR on SCC properties, design models for properties of the SCC, and optimize the mixes to achieve the best results. The properties considered were the durability of acid attack resistance (H2SO4 attack), salt attack resistance (MgSO4 attack), and water absorption. The heat resistance considered was weight reduction and residual compressive strength after heating the samples at a 200 °C and 400 °C. The results findings showed that CR and CCR negatively affect the acid and salt resistance of the SCC. Furthermore, CR negatively affects the heat resistance of the SCC, while CCR slightly improved it at 200 °C. The models developed using RSM were significant with high degrees of correlation and predictability. The optimum properties achieved 2.9% CR as a fine aggregate replacement and 5.5% CCR as a cement replacement. The developed models can predict the durability performance of SCC mixes in terms of acid and salt attack resistance and the effects of elevated temperatures using CR, CCR, and fly ash as the variables. This will reduce the need for carrying out experimental work, thereby reducing cost and time.

This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) in cement paste and concrete with a view to improve its suitability as a supplementary cementing material. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 °C, and after allowing cooling, sieved through sieve 75 μm and characterized. The effects of GHA admixed with 10 % RHA on cement paste and concrete were investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. Fresh concrete grade 20 of mixes made with partial replacement with GHA admixed with 10 % RHA in the order as above were tested for workability and hardened concrete tested for compressive, splitting tensile and flexural strengths at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The result of the investigations showed that GHA was of low reactivity and RHA was more reactive, with combined SiO2, Al2O3 and Fe2O3 content of 26.06 % and 80.33 %, respectively. The use of GHA admixed with 10 % RHA increased consistency, initial and final setting times of cement, but decreased linear shrinkage. The workability, compressive strength, splitting tensile strength and flexural strength of concrete decreased with increase in GHA-RHA content. However, 15 % would be considered as the optimum for structural concrete.

This study presents an investigation into the improvement of strength and durability properties of lateritic soil blocks using Millet Husk Ash (MHA) and Bitumen as additives so as to reduce its high cost and find alternative disposal method for agricultural waste. The lateritic soil samples were selected and treated with 0%, 10%, 15%, 20%, 30%, 40% and 50% of MHA by weight of laterite. The lateritic soil-MHA mixture was later admixed with 0%, 2%, 4%, 6%, 8%, 10%, 12% and 14% cutback bitumen solution by weight of laterite. Both the natural lateritic soil, lateritic and MHA, and the blend of Soil, MHA and Bitumen were first subjected to physical and chemical analysis using X-Ray Fluorescence (XRF) and Scanning Electromagnetic Machine (SEM) to determine their engineering properties followed by the performance test on bricks cast with varying quantities of the additives. A total of one hundred and ninety two (192) cubes were tested for moisture absorption, erodability and compressive strength tests. The result of the test showed that MHA and Bitumen acted as pozzolana in performance test on the soil blocks. Up to 30% MHAlaterite and 20% MHA admixed with 8% laterite were found to give optimum compressive strength of 10.8N/mm 2 and 10.9N/mm 2 for the bricks produced. The result also showed that about 50% MHA blended with 14% Bitumen solution ensured water tight bricks. Thus the use of MHA as partial replacement of cement will provide an economic use of by-product and consequently produce a cheaper soil block construction without comprising its strength.