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.
