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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Chemical Shrinkage and Cracking Resilience of Metakaolin Concrete
Author(s): A. Markandeya, D. G. Mapa, M. Fincan, N. Shanahan, Y. P. Stetsko, K. A. Riding, and A. Zayed
Publication: Materials Journal
Appears on pages(s): 99-106
Keywords: cracking; metakaolin; pozzolans; shrinkage
Abstract:Metakaolin (MK) is a highly reactive pozzolan obtained from calcining clay with high kaolinite content at elevated temperatures (650 to 800°C). Its use at replacement levels between 5 and 20% enhances concrete properties such as high early- and later-age strength and lowers the diffusion coefficient due to pore size refinement. However, early-age cracking due to higher temperature rise and autogenous shrinkage is a concern. This study reports on the effect of the inclusion of prewetted lightweight aggregates (LWAs) on early-age cracking under semi-adiabatic conditions and uniaxial restraint using a rigid cracking frame. Lower cracking tendency is reported based on the tensile stress-strength ratio and cracking temperature. The chemical shrinkage coefficient for MK is determined using shrinkage measurements and thermodynamic modeling (GEMS). These findings can be used to determine appropriate LWA replacement levels in MK-blended concrete mixtures to minimize shrinkage and cracking potential.
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