Chemical and Mechanical Characterization of Damage Evolution in Concrete due to External Sulfate Attack

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Title: Chemical and Mechanical Characterization of Damage Evolution in Concrete due to External Sulfate Attack

Author(s): A. Bonakdar, and B. Mobasher

Publication: Special Publication

Volume: 317

Issue:

Appears on pages(s): 1-12

Keywords: cement, chemical analysis, damage, expansion, fly ash, fracture, sulfate attack

Date: 6/1/2017

Abstract:
External sulfate attack is often described by a diffusion-reaction mechanism which leads to the decomposition of hardened cement paste and cracking of concrete. In most studies, the linear expansion of mortar/concrete prisms is measured according to ASTM C1012. Even though this test can be used to determine the suitability of a mixture for specific sulfate exposure conditions, it does not provide insights on the actual degradation process. This paper presents a series of experiments performed to quantify the damage evolution on cement-based mortars with and without fly ash. Conventional expansion tests were conducted, followed by measuring the chemical and mechanical changes on the cross section of the specimens using EDS and microhardness techniques. The overall damage was further evaluated using a novel flexural fracture test on the specimens. It was observed that partial replacement of cement with class F fly ash reduced the level of mechanical damage in exposure to sulfate attack.