Abstract
Magnesia-phosphate cements are fast setting materials which can be used for rapid repair. While they are typically brittle in nature, their ductility can be significantly improved by addition of fibers. This paper presents some results obtained with five different types of fibers, namely E-glass, polyester, polypropylene, polyamide, and metallic. E-glass and polyester fibers are usually destroyed by chemical reaction with ordinary Portland cement but are compatible with magnesia-phosphate cement. The fiber volume fraction ranged from 0.69% (metallic) to 1.32% (polyamide). The composites were prepared according to the premix method, the matrix being composed of 50% magnesia-phosphate cement and 50% sand. The behavior of such composites was compared to that of a control composite made with ordinary Portland cement based composite reinforced by 0.97% A.R. glass fibers. Besides the type of fiber and cement matrix, the test parameters included the age at loading (from 3 h to 90 days) and the exposure conditions by prior immersion in hot water or by cycles of wetting and drying. Test results include the load-deflection response, the modulus of rupture, the toughness indices, the residual strength factor and a comparison of the various modes of failure. It is pointed out that the performance of magnesia-phosphate cement composites, at 3 h of age, was about the same as that obtained at 28 days by the control composite. Moreover, when subjected to accelerated aging, these composites maintained their performance, and elastic-plastic behavior in bending was observed as polypropylene and metallic fibers were used.
Published Version
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