EFFECTS OF A SIZE IN BUNDLED FIBERS ON THE INTERFACIAL ZONE BETWEEN THE FIBERS AND THE CEMENT PASTE MATRIX

The effects of polymer used as a size for bundled fibers in cementitious composites were revealed by investigating the changes in microstructural features of the interfacial zone between the bundled fibers and cement paste matrix. Microstructures characterized by microhardness measurements were related to the flexural behavior of glass and carbon fiber reinforced cement prisms. Comparing the interfacial zone formed around sized glass fibers with that around size - free fibers, the sizes were found to affect the microstructure of the interfacial zone. The influence of size on the interfacial zone depends on the type of size. One size raised the microhardness of interfacial zone, while another kept the interfacial zone soft. These differences in microstructure of the interfacial zone between different sizes were reflected in the flexural behavior of fiber reinforced cement prisms.