Research On Polyoxymethylene Fiber Surface Modification And Mechanical Property Of Polyoxymethylene Fiber Reinforced Concrete

Fiber reinforced concrete defined as the cement based composite materials is one of thehigh performance concrete,based on cement paste、mortar and concrete matrix, reinforced bydiscontinuous short fibers or continuous long fibers, often referred to as “fiber concrete”. Thefibers currently adopted to reinforce concrete mainly focus on PP, PAN, PET, PVA, PA,Kevlar, carbon fiber and so on. Polyoxymethylene(POM) fiber is a high strength, highmodulus fiber developed in recent years with the excellent alkali corrosion resistanceperformance and excellent dispersion performance in the composite matrix. When POM fiberis applied to the concrete matrix, the high strength and high modulus performance canimprove the concrete strength, excellent alkali resistance can resist strong alkaline concrete,its excellent dispersion help it uniformly dispersing in the concrete mixing process, and thePOM fiber surface with weak polarity combined the concrete matrix with a good interface.Much works had this paper researched in and the conclusions drawn as following:In this paper, POM fibers were treated with salpeter solution, hydroxide solution, coronaand coupling agents solution, then the active ingredients and pattern of treated POM fiberssurface, strength of treated POM fibers were investigated. The results show that POM fibershave better alkaline resistance properties than acid and acid solution, alkaline solution, coronaand coupling KH-570solution can’t active the surface of POM fibers. Decentrality of POMfibers is best among POM, PP and PET fibers in the methyl cellulose solution andethanol-ethylene glycol solution.Interface bonding force between POM fibers and cement paste was researched by the wayof single fiber pull-out method under the consideration of POM fibers length embedded incement paste, sample curing time and water-binder ratio. Researches show that bonding forceincreased in the beginning with increasing embedded length of POM fiber in cement paste,then when the embedded length of POM fiber in cement paste in the range of6.9-9mm,binding force remained constant, finally when the embedded length above9mm, the bindingforce again increased with the POM fiber embedded length increased. But with prolonging thecuring time and water cement ratio increases, the binding force between POM fibers andcement paste decreased. In the fiber surface morphology analysis of pull-out fibers, thecombination between surface treated fibers and cement paste is better than untreated fibers,and POM fibers treated with coupling agent grafting after corona have best combination withcement paste.And the main mechanical property of POM fibers reinforced concrete with different fiberlength and contents is researched, including compressive strength, rupture strength, rip-tensilestrength, permeation resist, crack resist performance. The dispersion of POM fibers inconcrete and the bonding state between fiber and concrete is observed by SEM. The resultsshow that the compressive strength of fiber concrete decreased, the crack resistance and bending properties improved, and the POM fiber concrete showed good cracking prevention.