Critical observations for the evaluation of cement hydration models

Abstract

The development of computer models for cement hydration and microstructure development, with an explicit consideration of microstructure, has accelerated in the past 25 years, creating a need for a set of critical experimental observations that can be used in evaluating the model predictions. During this same time period, there have been rapid advances in experimental techniques for quantifying both the hydration rates and the produced microstructures. This paper utilizes several of these techniques to elaborate a preliminary set of experimental observations concerning the influence of water-to-cement ratio, cement particle size distribution, and curing conditions on hydration and microstructure development. Isothermal calorimetry provides a convenient measure of the ongoing hydration rates during the first 7 days of hydration, while low temperature calorimetry can be used to directly assess the percolation state of the capillary porosity and the quantity of freezable water in a hydrated cement paste. Conventional measurements of setting times, such as Vicat needle penetration, are related to the ongoing percolation transitions of the solids within the three-dimensional microstructure. Finally, since concretes in the field rarely experience saturated curing conditions, the influence of sealed curing on resultant degree of hydration and microstructure is examined. The presented data sets should provide a first step in performing a critical evaluation of existing and future computer models.

Comparative Study of Setting Time and Heat of Hydration Development of Portland Cement According to EN 196-3

“…In order to avoid the problems mentioned above and to be able to monitor the setting process, semi-adiabatic calorimetry (SAC) is an increasingly widespread method for determining the setting time of cementitious mixtures [10][11][12][13][14][15][16][17][18].…”

“…Recently, the measurement based on semi-adiabatic calorimetry (SAC) has become popular for determining the setting time of cementitious materials [10][11][12][13][14][15][16][17][18]. During the procedure, the change in the hydration heat development of the cement is monitored as the clinker minerals chemically react with the water, which results in heat generation (exothermic reaction).…”

Structural Approach for Numerical Internal Strain Modelling of Conglomerate Structures

“…The required relation expressed in mathematical terms could be obtained by computer simulation modeling which involves creation of composite structure simulation models (Bentz, 2011;Buffo-Lacarrière et al, 2007).…”