Multi-response optimization of post-fire residual compressive strength of high performance concrete

Abstract

This paper presents results of an experimental study undertaken to optimize the residual compressive strength of heated high performance concrete using the Taguchi off-line method and the utility concept. The design of experiments (DoEs) was first carried out by Taguchi method using a standard L9(34) orthogonal array (OA) of four factors with three material parameter levels. The factors considered in the context of high performance concrete were cement content, fly ash content, super-plasticizer content and fine aggregate content. The cube specimens were cast and heated up to 200°C, 400°C, 600°C and 800°C target temperatures. They were subsequently tested under axial compressive loads in cooled conditions. Based on the results, the material parameter responses were analyzed by utility concept to reduce the multi-characteristic response and to obtain single setting of optimized parameters in order to maximize the post-fire residual compressive strength of concrete. The results indicate that the best level of control factors paid their own contribution for compressive strength at various elevated temperatures. The cement content was found to be the most influencing parameter followed by fine aggregate content and fly ash dosage. The role of chemical admixture dosage was observed to be relatively less marked on the residual compressive strength of high performance concrete. The confirmation tests corroborated the theoretical optimum test conditions.