Abstract
One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate () and alumina () structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.
Highlights
It was reported that the alumina existing in the calcium aluminate cement concrete (CACC) considerably improved the mechanical features in comparison with conventional concrete
The presence of this structure at ambient temperature as a stable phase in CACCs has previously been established in similar studies [32,33]
This is a result of the different thermal expansion rates of the aggregate and cement paste appeared, which led to an 18% of reduction in the tensile strength compared to 400 °C
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Important mechanical features in this regard include the strength, elastic modulus, and deformation, in that they considerably affect the thermal performance of structural systems [5,6,8,9]. It was reported that the alumina existing in the CACC considerably improved the mechanical features in comparison with conventional concrete In this regard, the residual strength of the CACC was higher compared with that of the conventional concrete, especially for temperatures above 400 ◦ C. The impact of changes in the microstructure of CACC after experiencing heat and on the mechanical features of this concrete was explored. Data about this subject are scarce in the literature. To obtain a better understanding of the postfire performance of CACC, the observed results for this concrete were compared with the results reported in the literature for other concrete types, especially with the results of Khaliq et al [15]
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