Refereed Journals

The use of superplasticizers is very uncommon in many developing countries. However, its inclusion in concrete enhances concrete's mechanical and durability properties. There is a yawning gap in the literature on the performance of Sulphonated Naphthalene Formaldehyde (SNF) superplasticizers in concrete, especially in the sub-Saharan construction industry where the quality of aggregates used in production is questionable. This study produced two batches of concrete produced with locally sourced pit sand, with characteristic strength of 30 MPa. One batch was without the SNF superplasticizer to serve as a control, whereas the other batch was made with the incorporation of the superplasticizer. The fresh properties of slump and air content and the hardened properties of compressive and flexural strength, elastic, and dynamic moduli were investigated. Further, durability indicators comprising sorption, water absorption, sorptivity, chloride penetration, electrical surface resistivity, and acid attack were investigated. The results of the study demonstrated that the incorporation of SNF superplasticizers in concrete resulted in improved workability and a reduction in ion mobility within the concrete. This was attributed to a decrease in the presence of interconnected pores, leading to notable enhancements in mechanical properties such as increased strength, as well as improvements in both elastic and dynamic moduli. Moreover, concrete containing SNF superplasticizer protects the concrete much better from acid attack than those without SNF superplasticizer. The study recommends the use of SNF superplasticizers in concrete for improved workability, reduced ion movement via fewer interconnected pores, and enhanced mechanical properties, potentially boosting overall durability.

The detrimental impact of anthropogenic gases such as carbon dioxide, methane, and nitrous oxide has become a pressing concern across various industries. In this study, thermally activated clay (TAC) was investigated as a substitute for Portland cement in proportions ranging from 10 to 40 wt%. Compressive strength and efficiency factors were employed to ascertain the optimal mortar mixture. Both the control mortar and the optimal blend underwent capillary water sorptivity tests. Fourier Transformed Infrared spectroscopy (FT-IR) was utilized to gain insight into the hydration process and pozzolanic reaction within the mortar mixtures. Furthermore, the study assessed the impact of the optimized blended mortar on greenhouse gas emissions through estimated carbon dioxide equivalent values. Results revealed that incorporating 30% TAC attained the maximum strength of approximately 33, 36, and 48 MPa at 3, 7, and 28 days respectively compared with the other mortars. The mortar containing 30% TAC enhances both compressive strength and efficiency factors, demonstrating effective pozzolanic activity and minimal compromise on performance. Notably, the inclusion of 30% TAC also led to reduced water absorption rates, indicating improved durability-related performance. Additionally, the study uncovered the superior performance of the 30% TAC mix in terms of efficiency factors and carbon savings. FTIR analysis provided novel insights into the hydration and pozzolanic reactions induced by TAC, resulting in the formation of compounds contributing to enhanced compressive strength over time. This research advocates for the substitution of Portland cement with TAC as a low-carbon binder alternative to traditional Portland cement binders.

The high kaolinite content of metakaolin makes it valuable to other industries, thereby affecting its availability and affordability for the production of limestone calcined clay cement (LC³). This work presents a study on the potential utilization of low-grade clay in place of pure metakaolin in the preparation of LC³ for mortar formulations. CEM I was partially substituted with calcined clay and limestone by 20, 30, 40, and 50 wt.%. The weight ratio of calcined clay and limestone was maintained at 2:1 for all mixes and the water-to-binder ratio was 0.48. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and isothermal conduction calorimetry were used to study the hydration process and products after 28 days. Mechanical and durability assessments of the LC³ mortar specimens were conducted. LC³ specimens (marked LC20%, LC30%, LC40%, and LC50%) trailed the control sample by 1.2%, 4%, 9.8%, and 18%, respectively, at 28 days and 1.6%, 2.3%, 3.6%, and 5.5%, respectively, at 91 days. The optimum replacement of OPC clinker, calcined clay, and limestone was 20% (LC20%).

The recent emphasis on sustainable development in the construction industry has made it essential to develop construction and building materials that are not only affordable, but have minimal negative impact on the environment. This study investigates the valorisation of steel slag, which is mostly considered to be a waste material in several parts of the world, by blending with calcined impure kaolinitic clay to partially replace ordinary Portland cement (OPC) in the preparation of self-compacting concrete (SCC). OPC was substituted with steel slag at a constant level of 10%, whereas calcined clay replaced OPC at varying levels, ranging from 10 to 30% in a ternary blended mix. The hardened properties evaluated include compressive and flexural strengths. Samples containing only calcined clay showed a lower fluidity, which was significantly improved when steel slag was added to the mix. SCC containing 10% steel slag and 20% calcined clay obtained 28 days compressive strength, which was 3.6% higher than the reference cement concrete. An XRD analysis revealed a significant decrease in the peak heights of portlandite in mixtures containing steel slag and calcined clay, regardless of their replacement percentage. Generally, all the blended cement samples performed appreciably in resisting sulphate attack. The results of this study demonstrate that using steel slag and calcined clay together can significantly improve the fresh and hardened properties of SCC without compromising its mechanical properties.

Sustainable procurement adoption in the public sector construction organisation is still evolving in both developed and developing countries, researchers believe that its existence will aid in achieving sustainable development. This paper presents the level of implementation of sustainable procurement in public sector construction organisation in Ghana. Based on stratified and purposive sampling techniques data was collected from 193 government institutions. One-sample t-test was used to validate the data collected. The findings indicated that the simultaneous application of the economic, social and environmental aspects of sustainable procurement in construction were limited. It was revealed that nine out of the twenty-one of the three aspects of sustainable procurement practices was moderately implemented. The significant sustainable practices implemented were preventing nuisance from construction operations; providing employment to the community; clearly establishing needs and evaluate other options; value for money; decreasing water usage; reusing existing built assets; reducing water, land and air pollution and environmental management system. This suggests that government must encourage the incorporation of the considerations of economic, environmental and socially responsible policy goals within sustainable procurement practices of public sector instructions.