Interface Property Tailoring for Pseudo Strain-Hardening Cementitious Composites

Continuous Modeling Technique of Fiber Pullout from a Cement Matrix with Different Interface Mechanical Properties Using Finite Element Program

“…Using this relation, we can simulate the pullout of fibers in different types, for example, steel fiber with slip softening behavior, as seen in the experimental works of Naaman and Shah (1976) and Li et al (1991) and synthetic fibers with slip hardening behavior commonly observed in this fiber type, where the interfacial stress increases with slip distance (Wang et al (1988), Li et al (1995) and Ting et al (2015)). This hardening behavior is due to wear between the surfaces, occurring at the moment when low hardness fibers try to slide over the stiffer matrix, a resistance to movement is imposed by the accumulation of the fiber debris, and thus increases the interface shear stress.…”

“…To exemplify interface slip hardening behavior we referred the experimental test of Li et al (1995) where polyethylene fibers were added into a cement matrix. The geometric and mechanical properties of fiber, cement matrix, and interface parameters are listed in For the comparison, the same experimental test was referred to the analytical model of Lin and Li (1997) with a simple interface constitutive relationship adopted from Bao and Song (1993) to quantify the slip-hardening interface behavior, which is:…”

“…Therefore, we can say that the presented model integrated into the ANSYS is suitable for the modeling because it is more simple but capable of describing very well the fiber pullout process. Li et al (1995) and the analytic model of Lin and Li (1997) with different  values.…”

Methods of modifying the brittle behavior of cementitious composites

“…Also the interface will strongly influence the toughness of the composites and frictional bond [10] . Generally the interface zone is considerable weaker than the matrix due to the large calcium hydroxide crystals and higher porosity for the FRCCs with steel fiber or polypropylene fiber [9] , but the PVA fiber is a special organic fiber to the cementitious composites. The majority of fibers used to the cementitious composites, such as steel fiber, polypropylene fiber, etc, will not react with the hydration products of cement, but the investigations by Akers show that [11] , the PVA fiber performs surprisingly high chemical bonding between the PVA fiber and cement hydration products due to the strong hydrophilic characteristic or hydrogen intermolecular bond induced by the hydroxyl groups, and as the age increase, while there are no evident change in fiber properties, the bonding strength between fiber and cement-based matrix will increase due to an increase in interface bond with age.…”

“…That can be explained as follows: curing condition plays a significant influence on microstructure and macroscopical performance of cementitious composites. For fiber reinforced cementitious composites, there exists a distinctive layer of interface zone about 30-50 μm away from the fiber surface [9] . Also the interface will strongly influence the toughness of the composites and frictional bond [10] .…”