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Fine aggregates significantly affect the drying shrinkage in mortar, but concrete.  Limestone sand and blast furnace slag sand can reduce the mortar drying shrinkage.  Coarse aggregate characteristics play an important role on the concrete drying shrinkage property.  Coarse aggregate strain, specific surface area and pore structure of coarse aggregates are investigated.  Total amount of water content parameter on drying shrinkage is introduced.

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Pore structural changes in hardened cement pastes, subjected to drying and wetting/drying cycles, were studied at micrometer and nanometer levels. Characterization techniques included Nuclear Magnetic Resonance (NMR), nitrogen and water vapor adsorption, mercury intrusion porosimetry (MIP) and under-water weighing. Coarsening of pore structure was observed with MIP and increase in the true density of C-S-H was suggested by the result of under-water weighing. Decrease in specific surface area due to drying was observed with nitrogen adsorption, and water vapor adsorption associated with Excess Surface Work (ESW) analysis suggested a development of cohesive structure in C-S-H. NMR confirmed polymerization of silicate anion chains. The drying-induced coarsening of pore structure is probably attributed to polymerization of silicate anion chains and development of cohesive structure in C-S-H.

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