Abstract

The strength development in concrete with its age is essentially a constant volume solidification process, which is controlled by multivarious parameters. However, the concrete mixes are designed for 28 day’s target compressive strength. In a more general characterization, it can be said that increase in strength of concrete is achieved by decrease in water cement ratio and decrease in aggregate cement ratio. However, it is impossible to develop a precise mathematical model that can predict crisp numerical values of strength that correspond to crisp values of w/c ratio and a/c ratio. This is due to uncertainties involved in these parameters, the uncertain behavior of constituent materials, and tolerances. The potential of fuzzy logic in developing a model for characterization by approximate reasoning really lies here. This paper presents a modest attempt made to characterize 28 day’s strength of concrete using Fuzzy Inference System (FIS). The methodology consists of two steps; (1) developing the basic model using generalized Abram’s law and (2) validating the basic model, using the experimental data. The water-cement ratio and aggregate-cement ratio are treated as antecedents and 28 day’s strength is the consequent. The results have shown that, the fuzzy inference system provides a prudent way to capture uncertainty (non-statistical) in relationships among parameters that control the early strength of concrete.

Key words:  Early strength of concrete, water-cement ratio, aggregate-cement ratio, fuzzy inference system, antecedents, consequents, approximate reasoning.