Economical Mixtures to Reduce Both Thermal and Autogenous Shrinkage Contributions to Early-Age Cracking

Published

July 2, 2008

Author(s)

Dale P. Bentz, Max A. Peltz

Abstract

Early-age cracking continues to be a significant problem for new concrete construction. Two of the major contributors to such cracking are the heat released by cement hydration during the first few days of curing and the autogenous shrinkage that often occurs during the same timeframe. In this paper, three potential alternatives for reducing these contributions by modifying the concrete mixture proportions are investigated, namely increasing the water-to-cement ratio, utilizing a coarser cement, or replacing a portion of the portland cement with a coarse limestone powder. Each alternative reduces the heat generated per unit volume by either reducing the volumetric cement content or its early-age reactivity, and reduces autogenous shrinkage by increasing the interparticle spacing between grains in the three-dimensional microstructure. These reductions are quantified for paste and mortar systems by measuring their semi-adiabatic temperature rise and autogenous deformation, along with measurements of compressive strength to indicate the strength tradeoff that will be experienced in reducing the risk of early-age cracking. These mixtures each have the additional advantage that they should result in a cost savings in comparison to an initial (control) mixture.

Citation

Aci Materials Journal Journal

Pub Type

Journals

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Keywords

autogenous deformation, building technology, early-age cracking, mixture proportioning, thermal stresses

Citation

Bentz, D. and Peltz, M. (2008), Economical Mixtures to Reduce Both Thermal and Autogenous Shrinkage Contributions to Early-Age Cracking, Aci Materials Journal Journal, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860716 (Accessed April 23, 2024)