Relationships Between Microstructure and Engineering Properties

Abstract

ABSTRACTThe calculation of such macroscopic engineering properties as elastic modulus and compressive strength for cement pastes and concrete depends upon the establishment of a realistic model of the microstructure. Increasingly complex models are considered, which appear capable of predicting the elastic modulus in terms of a modified Rule of Mixtures. The same models are able to account for the broad features of the compressive strength, because strength is always scaled by the elastic modulus of the material. The actual value of the compressive or the bend strength is determined by the mechanics of crack initiation and crack propagation in the particular test used. Crack initiation is controlled by the defects present in the material and crack propagation by the fracture toughness of the different phases and the porosity in the microstructure. Thus the strength depends upon microstructure in a number of different but interrelated ways, determined by the fracture toughness of the material.