Physical and Chemical Characteristics of Hydrated Paste

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Durability of concrete is a function of performance of all three of its main components (hydrated cement paste, aggregate and (if present) reinforcement. This course will specifically focus on the influence of physical and chemical haracteristics of the of hydrated cement paste on the performance of concrete.

Hydrated cement paste (hcp) is a porous, multiphase material deposited in situ as a result of chemical reactions between clinker minerals and gypsum with water. The internal porosity of hcp plays an important role in controlling the durability of concrete as it influences the ingress of moisture (and any dissolved aggressive chemicals). The size and the degree of saturation of pores influence such properties of paste as drying shrinkage or freeze-thaw resistance.

The lectures will review volumetric distribution of phases in hcp (including porosity) and examine the influence of porosity on shrinkage, creep and freeze-thaw resistance of concrete. The interaction of solid phases present in hcp with aggressive chemicals (e.g. chlorides and sulfates) will be discussed to address the issue of resistance of concrete to chemical attack.