An Experimental Study of the Water-Cement Ratio and Concrete Strength

Abstract

Water cement ratio is always a burning question for casting concrete. Concrete is the most versatile construction materials and used as a substitute of stone which acts as artificial stone. The strength of this important construction material mostly depends on a proper water cement ratio. A wrong water cement ratio may produce weak concrete in spite of using 1st class ingredients of concrete. Hence determining a proper water cement ratio is one of the important factors of civil engineers worldwide. The first, less frequently mentioned fundamental presumptions for the strength versus water-cement ratio relationship are discussed, namely that (a) the strength of structural concrete is controlled by the strength of the cement paste contained within it; (b) the strength of a cement paste strongly depends on its porosity; and (c) the porosity (capillary) is a function of the water-cement ratio. The connection between concrete strength and water-cement ratio is based on this. For this relationship, many empirical formulations, or "strength formulas," have been established, such as the Abrams formula. These calculations, which often are straightforward but have limited validity, estimate the concrete strength only based on the water-cement ratio. In order to provide improvements, a new class of strength formulas is presented in this study. These formulas include a second independent variable in addition to the water-cement ratio, such as the amount of cement, water, paste, etc. This addition (a) increases the precision with which strength estimates are made (b) demonstrates that, when the water-cement ratio of two comparable concretes is changed, the concrete with the higher cement content will have a lower strength, and (c) demonstrates that the size of changes in concrete strength depends on whether the water-cement ratio is altered by changing the cement content or the water content. These predictions are supported by experimental data. The impact of the other type of porosity, the air content, on the strength of concrete is likewise explained using a formula. When this is combined with any reliable strength formula, the experimental results for both air-entrained and non-air-entrained concretes are well-fitted.