bonding performance of nylon tire cord yarns in fine grained concrete

polymeric yarns for reinforcing cement composites have got great interest in all over the world. in this research the performance of bonding between nylon tire cord grad yarns, and one kind of cement composite called fine grained concrete was studied. two kinds of nylon cord yarns, nylon 6 and 66, with different finesse were selected. the durability of yarns with time in alkaline media was investigated. meanwhile the effect of usual tire cord coating on bonding performance and alkaline durability of yarns were studied by mechanical testing and sem images. then the bonding of these yarns to cement paste and the effects of finesse on bonding performance were investigated by pull out tests. the results show that coating could enhance alkaline durability. results also show that yarns with higher finesse are more sensitive to alkaline media and their mechanical properties reduced more. sem images show that in general, alkali damage of nylon tire cord yarns was not deep and no significant changes were observed on the surface of filaments after exposed to alkali. the bonding of nylon tire cord to cement composite was suitable and no slippage was observed. the pull out behavior of finer yarns is better than coarse yarns. meanwhile tire cord coating could enhance bonding of yarns to cement paste.