A REVIEW OF THE EFFECTS OF WASTEWATER ON REINFORCED CONCRETE STRUCTURES IN NIGERIA

This paper reviews the degradation mechanism of wastewater on reinforced concrete structures with a view to finding what needs to be done to salvage these structures. Potential disintegrating agents in wastewater generated in Nigeria were identified and common degradation effects were examined. Regeneration, preventive and corrective techniques were noted. While noting that poor maintenance culture, lack of multidisciplinary research work and high cost of maintenance were major factors responsible for the high rate of deterioration. The paper, therefore, concluded with suggestions that could be employed to salvage these structures from total collapse. One of such approaches is to use admixtures, which could reduce the effect of acidic attack common in wastewater concrete structures. http://dx.doi.org/10.4314/njt.v35i2.

Performance of Steel Slag as Fine Aggregate in Structural Concrete

Suitability of using steel slag (SS) as substitute for sand in concrete was investigated. SS was collected from a dump site, crushed manually and sieved through between sieves No. 4 and 200. SS was characterized using XRF and XRD techniques. Concrete of mix ratio 1:2:4 was batched by weight with slag replacement levels of 0 to 100% of sand at 25% interval and the concrete specimens (cubes and beams) produced were cured in water for 7, 14, 28 and 56 days. Water demand, compressive strength as well as flexural strength of the concrete were determined. Results indicated that SS contained high amorphous silica (42.40%) and ferric oxides (31.90%) with traces of crystalline particles. The water-cement ratio reduced from 0.62 to 0.50 as slag proportion increased from 0% to 100% at slump range of 6010 mm. The strength of SS concrete increased with increase in proportion of SS. The study suggested that up to 50% of weight of sand could be replaced with slag to produce structural concrete.http://dx.doi.org/10.4314/njt.v34i3.

Comparative Analyses of Circularity Practices in Civil and Construction Engineering Between UK and Nigeria

Copyright: : © 2023 Olonade et al. The circular economy in the civil and construction engineering sectors is gaining momentum globally. The inadequate waste management system, especially in emerging nations, is quite concerning. Various waste sources such as construction and demolition (C&D), industrial wastes as well as agricultural wastes such as cassava peel, rice husk, and coconut fibre have been utilized in developing construction products. This study adopts the UK (United Kingdom) and Nigeria as two cases with critical analyses of the status quo and recommendations for promoting circularity. The existing studies on the circular use of waste construction products were comprehensively reviewed by mapping them against the Technology Readiness Level (TRL). The study addressed three research questions: (1) the existing locally available wastes used in civil and construction industries in the two studied countries, (2) the effects of these wastes on the properties of new construction products, and (3) visions to enhance circular use of wastes on civil and construction engineering practices. It is found that both countries have abundant industrial, agricultural, and demolition wastes that are potential materials for circularity in construction. While the TRL of utilizing these wastes is at an advanced stage in the UK, there is still a need for more concerted efforts to bring those wastes in Nigeria to a higher TRL. This study contributes to the existing body of knowledge by mapping the three aforementioned questions between the two studied countries, shedding light on continuous work in enhancing circular practices across the global civil and construction sectors.Royal Society UK IES\R2\212046, International Exchanges 2021 for funding the networking project entitled “Developing modular interlocking bricks and blocks with the entire waste reuse model in Nigeria and UK.