Location
University of Leeds
Keywords
hardened cement paste; drying shrinkage; calcium silicate hydrate; calcium hydroxide; pore structure
Abstract
The aim of the present study is to relate microstructure to the drying shrinkage of hardened cement paste. Three microstructural features, calcium silicate hydrate(C-S-H), calcium hydroxide(CH) and pore structure were studied. A new method to determine the C-S-H content of hardened cement paste is presented. Drying shrinkage behavior of cement pastes were investigated by drying specimens through successive steps of RH 100% to 7% RH and re-saturating the specimens. The total shrinkage of cement paste after drying to 7% RH and irreversible shrinkage were decreased with the increasing amount of C-S-H and CH. Prolonged curing resulted in a paste with finer pore structure and more weight loss when dried in lower humidity. For a certain paste, the same amount of weight loss induced less liner shrinkage in the 54-23% RH range than in the 100-54% RH range. The total shrinkage of cement paste after drying to 7% RH and irreversible shrinkage decreases with increasing amount of C-S-H and CH. The formation of C-S-H increase the resistance of cement paste to shrinkage rather than enhance drying shrinkage by providing more gel pores and empty of which would bring large stress on the solid skeleton.
Included in
Drying Shrinkage of Hardened Cement Paste and Its Relationship to the Microstructure
University of Leeds
The aim of the present study is to relate microstructure to the drying shrinkage of hardened cement paste. Three microstructural features, calcium silicate hydrate(C-S-H), calcium hydroxide(CH) and pore structure were studied. A new method to determine the C-S-H content of hardened cement paste is presented. Drying shrinkage behavior of cement pastes were investigated by drying specimens through successive steps of RH 100% to 7% RH and re-saturating the specimens. The total shrinkage of cement paste after drying to 7% RH and irreversible shrinkage were decreased with the increasing amount of C-S-H and CH. Prolonged curing resulted in a paste with finer pore structure and more weight loss when dried in lower humidity. For a certain paste, the same amount of weight loss induced less liner shrinkage in the 54-23% RH range than in the 100-54% RH range. The total shrinkage of cement paste after drying to 7% RH and irreversible shrinkage decreases with increasing amount of C-S-H and CH. The formation of C-S-H increase the resistance of cement paste to shrinkage rather than enhance drying shrinkage by providing more gel pores and empty of which would bring large stress on the solid skeleton.
