Shrinkage-Reducing Admixtures and Early-Age Desiccation in Cement Pastes and Mortars

Published

July 1, 2001

Author(s)

M R. Geiker, K K. Hansen

Abstract

Fundamental studies of the early-age desiccation of cement-based materials with and without a shrinkage-reducing admixture (SRA) have been performed. Studies have been conducted under both sealed and drying conditions. Physical measurements include mass loss, surface tension, x-ray absorption to map the drying profile, internal relative humidity, and autogenous deformation. Interestingly, although the SRA accelerates the drying of bulk solutions, in cement paste with a water-to-cement ratio of 0.35, it actually reduces the measured drying rate. Based on the accompanying x-ray absorption measurements and a simple three-dimensional microstructure model, an explanation for this observation is proposed. In sealed systems, at equivalent hydration times, the SRA maintains a greater internal RH and reduces the induced autogenous deformation. Thus, these admixtures should be beneficial to low w/c ratio concretes undergoing self-desiccation, in addition to their normal usage to reduce drying shrinkage.

Citation

Cement and Concrete Research

Volume

31

Issue

No. 7

Pub Type

Journals

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Keywords

building technology, cement paste, drying, humidity, shrinkage, surface tension

Citation

Geiker, M. and Hansen, K. (2001), Shrinkage-Reducing Admixtures and Early-Age Desiccation in Cement Pastes and Mortars, Cement and Concrete Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860316 (Accessed October 14, 2024)