• Charpentier, Thibault
• Stephant, Sylvain
• Chomat, Laure
• Nonat, André

Abstract

The physico-chemical properties of cementitious materials, such as transport properties or porosity are established during the hydration process. The latter which involves dissolution and precipitation reactions, is characterized by the mineralogical and structural changes associated to water state (evolution from evaporable water to chemically bound water and physically absorbed water) and chemical shrinkage. These physico-chemical properties are modified by the addition of supplementary cementitious materials like slag. Powers' model, based on the water state repartition, was initially developed to describe the hydration of Portland cement. This work aims to apply this model to slag blended cements hydration. Commercial cements with a variable amount of slag, ranging from 0% to 80% (% weight) are used in this study. First, the water state repartition was experimentally studied from 7 days to 1 year. The measurements of chemical shrinkage and bound water content show clearly the slowdown of the hydration with the presence of slag. The determination of the degree of hydration, by thermogravimetry analysis and by $^{29}$Si MAS NMR, is a crucial point which is discussed. Then Powers' model is applied to slag blended cements and the results are compare to experimental measurements.

Topics

• impedance spectroscopy
• cement
• thermogravimetry
• precipitation
• porosity
• Nuclear Magnetic Resonance spectroscopy