Brief Introduction
This course will cover physical and chemical characteristics of hydrated cement paste. In particular, it will examine the role of the paste microstructure (porosity) in controlling permeability and related durability characteristics of concrete such as freeze-thaw resistance, sulfate attack and carbonation. In addition, shrinkage and creep phenomena will also be discussed.
Description
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.
Knowledge
- Volumetric phase distribution
- Capillary stress vs RH and pore radius
- Shrinkage and creep
- Role of porosity and permeability
- Mechanism of frost damage (freezing and thawing process),
- Effects of deicing chemicals- scaling and chemical degradation
- Sulfate attack - types and methods of identification
- Carbonation
- Degradation in marine environment
Manufacturing and Hydration of Portland Cement
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The role of the w:c ratio and chemical admixtures will also be addressed. Various types of Portland cements and the relevant testing methods and specifications will be reviewed next....
Physical and Chemical Characteristics of Hydrated Paste
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This course will cover physical and chemical characteristics of hydrated cement paste. In addition, shrinkage and creep phenomena will also be discussed....
