Experimental Study On Impact Resistance Of PVA Fiber Reinforced Fly Ash-slag Base Polymer

Geopolymer Concrete(GC)has many advantages over traditional concrete.The first is the production process.The GC dissolves the raw materials through the chemical action of the alkali to directly produce the cementitious material or finished product without the need to go through the calcination and grinding processes of traditional cement.Secondly,in terms of material performance,GC is more excellent in strength,corrosion resistance,freeze resistance,impermeability and alkali-aggregate reaction.In the context of global attention to environmental protection,GC's advantages are increasingly prominent.Fiber Reinforced Concrete(FRC)is a general term for composite materials composed of fibers,cementitious materials and aggregates.The addition of fibers can make up for the defects of concrete itself.Research shows that different types of fibers can enhance the compressive strength,impact resistance and high temperature resistance of concrete.Under the current situation,conflicts in various regions have intensified.Large-scale energy sources,potential safety hazards in factories,and the impact of vehicles on road barriers have caused various types of buildings to experience strong impact loads during their life cycle.Unlike the static loads that FRC is usually subjected to,these impacts tend to cause greater damage to FRC.Therefore,it is very necessary to study the impact resistance of fiber geopolymer concrete(FGC).It has certain significance for the development of environmentally friendly concrete materials with excellent mechanical properties and the theoretical basis for the application of FGC in actual engineering.In this project,the static axial compression and impact resistance of polyvinyl alcohol(PVA)fiber toughened fly ash-slag composite base polymer concrete(PFRGC)were studied,and the content of low calcium fly ash and PVA fiber were studie d The influence of the axial pressure and impact resistance of PFGC is explained at a micro level through the scanning electron microscope(SEM).The failure mode,static mechanical index change law and impact resistance change law are obtained.The result s showed that:1)With the increase in the content of low-calcium fly ash and the content of PVA fiber,the strength and elastic modulus of the specimen gradually decreased,while the Poisson's ratio increased first and then decreased.2)In the PFGC with the content of plain GC and PVA fiber being 0.6%,the peak stress of the specimen gradually decreases with the increase of the content of fly ash;when the content of PVA fiber is 1.2%,with the addition of fly ash As the amount increases,the peak stress of the specimen decreases first and then increases.3)Under the similar logarithmic strain rate,the PFGC dynamic increase coefficient corresponding to 0.6% of plain GC and PVA fiber is not much different;the PF RGC dynamic increase coefficient of 1.2% of PVA fiber is greater than the other two PVA Test piece group with fiber content.In plain GC,when the fly ash content is 100%,the dynamic increase coefficient of the specimen increases significantly.With the PVA fiber-incorporated test piece group,as the fly ash content increases,the dynamic increase coefficient of the test piece gradually increases.4)The energy absorbed by PFRGC with a PVA fiber content of 0.6% is almost the same as the energy absorbed by plain geopolymer concrete;when the PVA fib er content is 1.2% of the volume content,the energy absorbed by the test piece is significantly reduced.In plain GC,when the amount of fly ash exceeds 80%,the energy absorbed by the test piece drops sharply;when the amount of PVA fiber is 0.6%,as the amount of fly ash increases,the energy absorbed by the test piece The values are not much different.When the amount of PVA fiber is 1.2%,as the amount of fly ash increases,the energy absorbed by the specimen decreases first and then increases.5)SEM test shows that compared with ordinary concrete,the combination of coarse aggregate and cementitious material in GC is very tight,and the interface transition area is not seen from the microscopic image.As the content of fly ash increases,the number of complete spherical fly ash particles remaining in the cementitious material gradually increases,and the number of cracks in the matrix also gradually increases,which in turn causes the compressive strength of the specimen axis.The incorporation of PVA fiber reduces the alkali-excited reaction of geopolymer concrete.The optimal PVA fiber content under this test condition is 0.6% of the volume content.Under this test condition,the plain GC mixed with 60% fly ash still has good mechanical properties;the integrated split Hopkinson pressure bar test and scanning electron microscopy test,the optimal content of PVA fiber is 0.6%.