Strength Characteristics of Superplasticizer-retempered Concrete using Chryso Quad 622 under Tropical Construction Site Conditions in Nigeria.
1Akintola, M. A. ; 1 Labiran, J. O; 2Akinsanya, A. Y., *3Olowu, O. A. and 1Adebambo, O. M…
1Department of Civil Engineering, Faculty of Engineering, University of Ibadan, Oyo, Nigeria.
2Department of Building Technology, College of Environmental Science and Technology, University of Science and Technology, Ikorodu, Lagos, Nigeria.
3Department of Building Technology, School of Environmental Studies, Yaba College of Technology, Lagos, Nigeria..
DOI: 10.36108/laujoces/6202.61.0241
Abstract
Scholarly evidence suggests that the southwest region of Nigeria has more manufacturing, construction, and engineering sectors, which increase population, social crises, seasonal flooding, and environmental pollution. These have significantly affected the ease of transporting construction materials in the metropolis. Additionally, some studies note that the average tropicalhot ambient temperatures of 32°C often impact the early setting of ready-mix concrete due to excessive evaporation and insufficient moisture for hydration, resulting in lower concrete strength and durability. Many construction industries rely on ready-mix concrete for their operations. Over the years, challenges faced by ready-mix concrete in Lagos include, but are not limited to, untimely delivery, which results in premature stiffening. These problems directly and indirectly affect project costs, quality, and functionality of the structure. Studies show that stakeholders suffer losses from wasted concrete while relying on the common practice of restoring (retempering) stiff concrete with water, re-mixing, heating, or retardants, which often falls short of the international standards. Experts have long emphasized the importance of maintaining the integrity, performance, durability, and ecological sustainability of such concrete in engineering projects. This study aims to address these concerns by using natural aggregates at a 0.4 w/c ratio with an adopted admixture (Chryso Quad 622 TDS) superplasticizer for retempering stiff concrete. Observations indicate that retempered concrete at 30, 60, 90, and 120 minutes showsa significant increase in compressive and flexural strengths compared to the control specimen. Correlation and regression analyses reveal a strong relationship between the control and superplasticized retempered concrete. This research provides scientific evidence and valuable information for practitioners and academia on the use of superplasticizer retempering, forming a basis for decision-making among stakeholders.
Keywords: Southwest, Concrete, Chryso-quad-622, Ready-mixed, Retempering, Superplasticizer, Workability, Re-mix.