Study Of Polypropylene Fiber And Polyacrylonitrile Fiber On Properties Of Concrete

Based on the prospects for development with synthetic fiber, this article selectsPolypropylene fiber of6mm,12mm,19mm, and Polyacrylonitrile fiber of12mm,19mm,30mm to study the effect of fiber’s length and dosage on compressive strength, flexuralstrength, abrasion, anti-assault and freeze-thaw resistance of concrete. The researchcontents include:(1) Make300specimen of100mm×100mm×100mm and149specimen of100mm×100mm×400mm to measure the compressive strength, flexural strength,anti-assault performance. The research shows6mm and12mm polyacrylonitrile fiber canincrease the compressive strength; the compressive strength of polypropylene fiberconcrete in early age is inhibited, but with the age growing there shows obviousreinforcing effect. In the flexural strength test, the more dosage is, the more abviouspromoting effect of polyacrylonitrile fiber on56day concrete than28day. WhenPolypropylene fiber is longer, it is less conducive to improve flexural strength, butpolypropylene fiber group reached the similar maximum increase of about16%at thedosage of0.9kg/m3. In anti-assault test,12mm polypropylene fiber group is the best while19mm polyacrylonitrile fiber one is the worst.(2) Make114specimen of150mm×150mm×150mm and50specimen of100mm×100mm×400mm to measure the abradability and freeze-thaw resistance. Theresult shows: in a certain dosage below, the longer polyacrylonitrile fiber group has a better28-day abradability, but the content become smaller rapidly with the increase of fiberlength. The56day wear resistance of polyacrylonitrile fiber group is similar with the lawof compressive strength. Wear resistance of12mm and19mm polypropylene fiber groupincreases overally with dosage, but in a significant different speed,30mm polypropylenefiber group has a poor wear resistance and doesn’t reflect any law. Freeze-thaw resistanceof19mm polyacrylonitrile fiber group decreased first and then increased, all of them canwithstand300cycles;12mm polyacrylonitrile fiber concrete can withstand300cycles in0.9kg/m3;6mm polyacrylonitrile fiber and12mm polypropylene fiber one can withstand300cycles in1.3kg/m3;19mm,30mm polypropylene fiber one can withstand300cycles in 1.7kg/m3.In order to observe the effect of fiber content on the matrix and interface to supportthe analysis of the mechanism of experimental data, the study selects four dosage groups ina certain length group of each fiber to conduct56-day SEM analysis. Combined with theexperimental phenomena and data, this paper analysis the inner mechanism, easy to give awider understanding of the effect of synthetic fiber.