STP745: Compliance Measured Fracture Toughness of Mortar and Fiber Reinforced Mortar

    Visalvanich, K
    Research assistant and associate professor of structural design, University of Illinois at Chicago Circle, Chicago, Ill.

    Naaman, AE
    Research assistant and associate professor of structural design, University of Illinois at Chicago Circle, Chicago, Ill.

    Pages: 16    Published: Jan 1981


    Abstract

    Contoured double cantilever beams 610 mm (24 in.) long were tested to measure the fracture parameters of plain and fiber reinforced mortar. The crack extension, the crack opening displacement (COD) and the crack opening of the cantilever's arms at the loading points were experimentally recorded in function of applied loads. The unloading-reloading technique was used to measure the compliance of the specimens. Slow crack growth was observed and the specimens experienced a permanent deformation at unloading. The permanent deformation was significant and increased linearly with crack extension for plain mortar and at a faster rate for fiber reinforced mortar. Specimens' compliances measured with and without the effect of the permanent deformation are compared and are shown to be substantially different. It is observed that the apparent critical stress intensity factor of plain mortar stabilizes at a crack extension of about 203 mm (8 in.) but no stabilization is observed for fiber reinforced specimens. One of the significant findings of this study is that cracks in mortar start propagating when their opening angle reaches a critical value called the critical crack opening angle (COA) regardless of their length.

    Keywords:

    mortar, concrete, fiber concrete, fracture mechanics, double cantilever beam, fracture toughness, COD, compliance, crack opening angle, crack propagation, composite materials


    Paper ID: STP28303S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP28303S


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