New Approach to Reduce Early-Age Shrinkage of Cement-Based Materials

Author(s): Keisuke Takahashi, Thomas Bier, Takayuki Aoki
Paper category: Conference
Book Title: 8th International RILEM Symposium on Self-Compacting Concrete - SCC 2016
Editor: Kamal H. Khayat
ISBN: 978-2-35158-156-8
e-ISBN: 978-2-35158-157-5
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 89-99
Total Pages: 11
Language: English

Abstract: Shrinkage of cement-based materials under drying conditions at early ages of up to 24 h after production has become of great concern due to recurrent problems with cracking in high strength concretes and self-consolidating concretes. Cracks provoked by early-age shrinkage are considerably deeper and more serious than those formed by drying induced under hygral gradients in hardened concretes. Nevertheless, relatively little research on dimensional stability has been directed at the reasons for the changes seen at early ages. This work investigates the dimensional stability and oscillatory rheology of cement-based mortars, shows the mechanism of early-age shrinkage, and describes the effects of polyol-based agents on reducing early-age shrinkage. Our results indicate that, in addition to capillary pore pressure, changes in early-age shrinkage are readily explicable by the upward movement of water. Utilizing a specific polyol-based agent showed a significant decrease of early-age shrinkage. The corresponding mechanism may be explained by the reduced surface tension of the pore water as well as water retained at the ethylene oxide adduct, and by nanoscale micelles of the agents fitting into capillary pores in the mortars and subsequently acting as stress absorbers.

Online publication: 2016
Publication Type: full_text
Public price (Euros): 0.00