Computational Materials Science of Cement-Based Materials

Abstract

Cement-based materials are random composite materials over many length scales. In common with any random material, the two main problems that must be solved to obtain quantitative theoretical understanding of microstructure-property relationships are: (1) what actually is the microstructure, and (2) given enough knowledge of a micro-structure, how can properties be calculated?In the past few decades, physicists and chemists have studied microstructure/property relationships for atomically disordered materials like semiconductor and metallic glasses, while mechanical engineers have done the same for continuum problems of macroscopic inclusions of one material distributed in a matrix of a second material. With the large memories and fast computational speeds of late 20th-century computers, it is now possible to attack problems that lie between these two extremes, namely random grain problems like those of cement-based and ceramic materials. For these kinds of materials, the important randomness for most problems is at the grain or particle level, not the atomic level, and is complicated by the fact that their microstructure changes markedly on time scales of hours and days, either due to sintering (ceramics), or hydration reactions (cement-based materials). The following sections of this paper describe how microstructures are simulated and properties like electrical conductivity and elastic moduli are computed-mostly for cement-based materials, but with some mention of parallel work on ceramic materials.