Optimization of the material structure and composition of cement based composites

Abstract

The materials considered in the paper are called concrete-like composites or materials with cement based matrices. These are not only ordinary and high performance concretes, but also materials with different admixtures, dispersed fibre reinforcement, polymers, etc. The matrix may be improved by several procedures and in this continuous phase different inclusions are randomly dispersed. The concretes, when treated as composite materials, may be studied and designed using modem methods developed for advanced high strength composites and mathematical optimization. In the paper a few important objective functions (criteria), constraints and variables are examined from the viewpoint of material design. The fracture energy is considered as an important feature of the material resistance against cracking. The amount of the fracture energy required for a given mode of rupture may be calculated using more or less approximate formulae, based on simplified assumptions. The main aim of the paper is to demonstrate through simple examples how the optimization approach may be used in practical situations of the design of high performance concretes.