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Oil pollution causes deterioration of the physical, chemical, mechanical, and geotechnical characteristics of affected soil leading to loss of soil productivity for engineering purposes. Different stabilization methods serve as a remedy for such soil to regain its loss engineering properties. This study was concerned with the utilization of lime to stabilize crude oil contaminated soil and to investigate its efficacy for soil stabilization. The study also focused on determining the geotechnical properties of crude oil contamination and matching the result with standard specifications established for engineering works. Hydrated lime, expansive clayey soil, contaminated soil, and potable water were the materials used for the experimental investigation. The contaminated soil was treated with 6.5% lime and 0–20% crude oil contaminated materials obtained from oil exploration sites in North-Eastern Nigeria and per standard test method for laboratory evaluation of consistency limits, compaction properties, California bearing ratio (CBR), and microstructural and mineralogical assessments. The experimental results obtained were further tested statistically through one-way ANOVA and F-statistics to establish the source of variation for the geotechnical properties, while multiple linear regression and correlation statistics helped draw the connection between the consistency limits, compaction, and CBR properties of the soil-lime-COCM blend. Results indicated a coefficient of determination of 99.86. The contaminated soil materials were found to show optimal performance at a 5% ratio and 6.5% of lime for civil construction purposes.

In this research study, a constrained simplex optimization method was adapted for the evaluation of green concrete’s mechanical property constituting of two-component mixture problem of cement and saw dust ash (SDA), which is a derivative from industrial residue. This experiential research will provide avenue for the recycle and incorporation of waste materials to achieve sustainability and control indiscriminate disposal of waste. The formulated components constrained were realized from the relevant literature studies to obtain the feasible planes in the simplex, and from this computation approach using I-optimality, the design mixture proportions and experimental runs were derived. The experimental results obtained from the laboratory experiments showed a maximum compressive strength of 31.13 N/mm2 with a ratio of 0.875 : 0.125 for cement and SDA, respectively, and a flexural strength of 9.49 N/mm2 with a ratio of 1 : 0 for cement and SDA, respectively; the results were observed to decline linearly with the further addition of SDA. The details generated from laboratory program were utilized for the development of the EVD model through fits statistical evaluation, ANOVA, diagnostic test and influence statistics, numerical optimization, and graphical statistical computations to analyze the datasets and locate the optimal levels of mixture ingredients using desirability function. A desirability score of 0.990 was derived at a mix ratio of 0.89 : 0.110 for the two components, cement and SDA, to produce a maximized compressive strength and a flexural strength of 31.102 N/mm2 and 9.384 N/mm2, respectively. Furthermore, the test of adequacy of the generated EVD model was carried out through simulation and statistical validation exercises using the F-test and student’s t-test, and the outcome signified a good correlation between the EVD model-simulated and actual values with p value >0.05.

This study presents the use of sawdust ash as a substitute in the production of sustainable building materials. Inappropriate dispose of wood-waste causes serious environmental problems as it results in atmospheric degradation, emissions of greenhouse gases and the destruction of aquatic and organic products. This review article combines research results from past studies into the usage of sawdust as an alternative for essential elements in construction composites. The result of this study shows that structural concrete can be manufactured with compressive strengths more than 20 MPa by replacing moderately 5–17% of the sand with sawdust or 5–15% of the cement with sawdust ash. By partially substituting sawdust that ranges between 10 and 30% of sand used in the production of blocks and bricks, sawdust blocks and bricks having compressive strengths greater than 3 MPa can be created. According to the findings of this study, sawdust has the potential to make construction composites that are strong, absorb water, and have an elastic modulus that meet international standards. The study concludes that sawdust composites are intriguing due to having hushed heat conductivity, a prominent sound absorption, as well as efficient sound wadding. From the findings, it is demonstrated that an increase in the utilization of sawdust for construction purposes will reduce the possibility of sawdust as a pollution to the environment, and will also ease the costs of disposal.

Timber is a material used for structural purposes in construction. Therefore, it is crucial to understand the characteristics of timber, particularly its strength and the factors that influence it. In this study, timbers studied were Brachystegia eurycoma (Eku), Entandrophragma cylindricum (Sapele) and Gmelina Arborea (Melina). A personal visit to the forest where they were freshly retrieved allowed for the collection of samples of timber from varied ages. By counting the number of annual growth rings, which are a combination of early wood and late wood, it was possible to establish the age of the wood. The acquired samples were cut to standard sizes in accordance with BS 373 1957 (Imprint 1999), 20mm X 20mm X 60mm for determining the maximum compressive strength parallel to grain, 20mm X 20mm X 300mm for determining the bending strength, and 20mm X 20mm X 20mm for static stress strength. Results obtained showed that Eku is better in compressive strength and Sapele is worthier in bending strength. The maximum compressive strength value was 49.31kN/m2 (at 45years), 45.89kN/m2 (at 60years) and 11.30kN/m2 (at 25years), maximum bending strength were 187.55kN/m2 (at 35years), 278.79kN/m2 (at 70years) and 176.36kN/m2 (at 20years) and shear strength were 10.05kN/m2 (at 50years), 9.22kN/m2 (at 70years) and 10.91kN/m2 (at 25years) for Eku, Sapele and Melina timbers respectively. In conclusion, it was determined that the strength of wood is influenced by the age of the wood.