Modelling of structural performance and sustainability of concrete produced with different water – Cement ratio and superplasticizer using multi-linear regression model

Abstract

Application of high-water cement ratio has been affecting the structural performance of concrete in service. Its negative impacts on construction sectors such as compromising concrete integrity, strength and elastic modulus require urgent attention. This study investigates the strengths, sustainability and durability of concrete produced with low water – cement ratio and Optima 206 Superplasticizer. The study aims at eradicating the issue of sudden collapse of concrete structures emanating from the use of high water - cement ratio, poor mix proportion and poor workability. In the experiment, the two different water – cement (W/C) ratios (0.6 and 0.43) with 1:2:3 concrete mix proportion were used for concrete production. The concrete samples produced were cured in water for 3, 7 and 28 days, respectively. Concurrently, the fresh and hardened properties of concrete were determined in accordance with SANS 10100 – 2: 2014, SANS5862-1:2006, SANS5863: 2006, and SANS 50196 – 3 standards while the results of investigations were modeled with multilinear regression analysis. The experimental results showed that concrete with 0.43 W/C surpassed that of 0.6 W/C in compressive, tensile and flexural strengths, modulus of elasticity (MOE), and Variation in MOE by 59.09, 60.94, 61.01, 10.8 and 29.7% respectively with the help of optima 206 superplasticizer. Also, the water absorption (WA) and carbon dioxide emissions from 0.43 W/C – concrete are by 1.36 and 3.60% less than that of 0.6 W/C ratio – concrete, thus, increase the concrete durability and environmental sustainability. Likewise, the optimum compressive, tensile, and flexural strengths, and modulus of elasticity (MOE) of 0.43 - W/C ratio – concrete predicted by regression model are by 29.2%, 80.4%, 45.8% and 9.9% more than that of 0.6 W/C ratio-concrete with coefficient of determination (R 2 ) values range of 0.971 - 0.976 indicating the strong fixing of the data by the statistical model while its WA reduced to 0.064%. In conclusion, the binary application of low W/C ratio (such as 0.43), Optima 206 superplasticizer and progressive increase in concrete’s curing ages are good for the production of sustainable concrete for industrial use. Also, based on experimental and model’s predictions, application of 0.43 W/C ratio together with superplasticizer is recommended for the production of sustainable concrete for the construction of high-strength infrastructures such as high-rise buildings, beams, columns, slabs, bridges, culverts and road – pavements. For better improvement, further investigation is required on application of low W/C ratio such as 0.43 W/C ratio on concrete’s durability and variation in MOE. “a” is Sieve analysis of coarse aggregate (Granite) which is one of good concrete materials“b” is the Tensile Strength of concrete Produced with 0.6 and 0.43 Water – Cement Ratios using Optima 206 Superplasticizer“c” is the Compressive Strength of concrete Produced with 0.6 and 0.43 Water – Cement Ratios using Optima 206 Superplasticizer“d” is the Modulus of Elasticity of concrete Produced with 0.6 and 0.43 Water – Cement Ratios using Optima 206 Superplasticizer • Application of low water – cement (W/C)) ratio in concrete helped in increasing the workability of concrete for better strength formation. • With the help of optima 206 superplasticizer, workable concretes were produced using low water – cement ratio of 0.43 which developed good strength than that 0.6 W/C ratio – concrete. • The 0.43 W/C ratio – concrete compressive strength is by 59% greater than that of concrete with 0.6 W/C ratio • Application of optima 206 superplasticizer together with low W/C such as 0.43 helped in controlling the flaws associated with production of less strength concrete structures which resulted into collapse and damages of the structures • The high strength concrete produced in this study is recommended for the construction of building materials in the global construction industries.