Effects of randomly distributed discrete short PVA fibers on impact strength of cement based composite

The aim of this research is to investigate the performance of randomly distributed polyvinyl alcohol (PVA)fibers of 6 mm length in cementitious composite. Based on total weight, three fiber contents (0.5%, 1% and 1.5%) byweight of cement were evaluated for their effect on static and dynamic mechanical properties of hardened mixtures.Providing a basis for comparison, control specimens were cast without fly ash. For all mixtures, water to cement ratiokept constant (0.45) and the maximum aggregate size was taken 4.75 mm. Poly carboxylate super plasticizer also used,1.5% by weight of cement to keep flow ability of the mix. All casted experiments demolded after 24 hours and cured insaturated lime water for 28 days and tested at the day of 35. By carrying out basic mechanical tests, it was observedthat presence of PVA fibers slightly decrease the compressive strength but increase the flexural strength ofcementitious composite. Major influence was observed in tensile and impact behavior. The absorbed impact energyprovided by the mechanisms of matrix cracking, PVA fiber/matrix interface debonding and fiber rupture. The SEManalysis showed that the introduced PVA fiber acted as bridge across the crack, which improved the load-transferefficiency and reduce the spalling of fragments. The experimental result showed that the addition of PVA fibers at1.5% by weight of cement is the optimal improvement in the flexural, tensile and impact resistance of experiments.

کلیدواژه ها:

PVA- fiber ، cementitious composite ، impact load ، energy absorption