Page 51 - Handbook of Thermal Analysis of Construction Materials

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2

Introduction to Portland

Cement Concrete

Concrete, made from cement, aggregates, chemical admixtures,
mineral admixtures, and water, comprises in quantity the largest of all
synthesized materials. The active constituent of concrete is cement paste
and the performance of concrete is largely determined by the nature of the
cement paste. Admixtures are chemicals that are added to concrete for
obtaining some beneficial effects such as better workability, strength,
durability, acceleration, retardation, air entrainment, water reduction, plas-
ticity, etc. Mineral admixtures, such as blast furnace slag, fly ash, silica
fume, and others, are also incorporated into concrete to improve its quality.
The performance of concrete depends on the quality of the ingre-
dients, their proportions, placement, and exposure conditions. For example,
the quality of the raw materials used for the manufacture of clinker, the
calcining conditions, the fineness and particle size of the cement, the
relative proportions of the cement phases, and the amount of mixing water
influence the physico-chemical behavior of the hardened cement paste in
concrete. In addition, the cement type, nature of fine and coarse aggregates,
water, temperature of mixing, admixture, and the environment will deter-
mine the physical, chemical, and durability aspects of concrete. Thermal
analysis techniques are widely applied to investigate the physico-chemical
behaviors of cement compounds, cement, and concrete subjected to various
conditions.

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