One difference between fiber-reinforced polymer (FRP) and fabric-reinforced cementitious matrix (FRCM) systems is the mechanical behavior in tension of the composite. FRP systems are linear elastic until failure, and their ultimate tensile strain is limited by the ultimate strain of the fibers.
Conversely, the tensile behavior of FRCM systems is a bit more complex, having three different phases. In the first phase, the load is carried primarily by the cementitious matrix until it cracks. In the second phase, the matrix undergoes a multicracking process, resulting in transfer of stresses from the reinforcing fabric to the matrix, with some debonding at the fabric-matrix interface. In the third phase, the composite system behaves almost linearly until failure occurs due to the progressive rupture of the roving fiber filaments and debonding of the fabric from the matrix. In this phase the load is carried almost exclusively by the fabric. The bond strength of FRCM to the substrate material is strongly affected by the type of fibers, fiber sizing, mesh layout, composition of the matrix, substrate properties, and quality of the surface preparation.
Also, the brittle “unzipping” debonding failure that is typical of FRP systems does not occur with FRCM systems. FRCM typically fails due to progressive slippage of the fibers within the cementitious matrix, or delamination at the fiber-matrix interface. The fiber slippage is typically initiated at crack locations, and is caused by the gradual loss of bond between the fibers and the matrix or by the gradual rupture of the fibers or both.
