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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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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: Submicrocracking in Cement Paste and Mortar
Author(s): Emmanuel K. Attiogbe and David Darwin
Publication: Materials Journal
Appears on pages(s): 491-500
Keywords: cement pastes; compression; concretes; cracking (fracturing); electron microscopes; measurement; microcracking; microstructure; strains; mortars (material); stresses; stress-strain diagram; Materials Research
Abstract:Submicroscopic cracking of cement paste and mortar under uniaxial compression is measured and compared to applied strain. Cement paste specimens with water-cement ratios of 0.7, 0.5, and 0.3 and mortar specimens with a water-cement ratio of 0.5 were tested at ages ranging from 27 to 29 days. After loading, slices of material were removed for study at a magnification of 1250 x in a scanning electron microscope. Cracking on transverse and longitudinal surfaces was measured, and three-dimensional crack distributions were obtained from the surface crack data. The research demonstrates that surface crack density in cement paste and mortar is an order of magnitude greater than the density of bond and mortar microcracks in concrete at the same value of compressive strain. The mean size of submicrocracks increases with increasing compressive strain, while the number of cracks per unit volume decreases. Differences in water-cement ratio have a small but measurable effect on the crack distributions. Crack density is lower initially in mortar than in cement paste but increases more rapidly as compressive strain increases.
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