Prediction of concrete strength from the development of cement paste microstructure

Concrete is a very complex composite material. Due to this complexity it is difficult to predict its properties. Knowledge about microstructural properties of concrete allows prediction of macroscopic properties from known input parameters. Benefits are reduction of necessary testing methods, optimisation of mix design procedures and early determination of concrete properties without waiting for 28-day strength determination. In this study, an attempt is made to predict the compressive strength development of standard concrete cubes. Three concrete mixtures were prepared with similar w/c ratio. Compressive strengths at 1, 7, and 28 d were tested. The Hymostruc cement hydration program is used to compute the expected degree of hydration for cement at 1, 7, and 28 days. Gel-space ratio as defined by Powers and Brownyard is calculated and related to compressive strength of cement mortar. The data about compressive strength of cement mortar is used to predict compressive strength of concrete, at ages of 1, 7 and 28 days for comparison to the experimental data.