Experimental Study On Impact Resistance Of Layered Fiber-reinforced Cementitious Composite

Fiber Reinforced Cementitious Composite is a new kind of material with high ductility and dynamic compressive strength,which is suit for impact resistance.Different kinds of fiber reinforce the cementitious composite in different way and adding different kinds of fiber into the composite can improve the material's performance.However,the difference among fibers' material properties restrict their reinforce behavior in cementitious composite.Therefore,Hybrid Fiber Engineered Cementitious Composite(HFECC)directly mixes different fibers in cementitious composite may not has the best reinforce effect.A new way has been adopted in the paper to solve this problem:adding different fibers into layered cementitious composite.PVA fiber and steel fiber have been introduced into the experiment and the impact resistance of the Layered Fiber-reinforced Cementitious Composite have been tested.The test method reference the drop weight test that recommend by ACI Committee 544 and the impact number of specimen reaching its ultimate failure can be used to judge the specimen's impact resistance.Experiments care the influences of impact surfaces and fiber-layer thickness on the material's impact resistance.Through the failure mode and failure mechanism of the specimens,the following conclusions can be obtained:When the surface of steel fiber layer receives direct impact,the energy absorption of Layered Fiber-reinforced Cementitious Composite increases and then decreases with the increase of PVA layer thickness.When the thickness is 10mm,the energy absorption reaches the peak point,compared with the HFECC,the impact resistance increases 29%;furthermore,with increasing the thickness of PVA layer,the layered specimens' ductility also improves,the failure mode turned form fragile to plastic and the specimens keep in one piece.When the surface of PVA layer receives direct impact,the energy absorption of Layered Fiber-reinforced Cementitious Composite also increases and then decreases with the increase of PVA layer thickness.When the thickness is 15mm,the energy absorption reaches the peak point,the impact resistance equal with that of the HFECC.Specimens' ductility also shows the same tendency;Because the steel fiber reinforced layer settled in the tensile region,most specimens show the failure mode of fragile.With increasing the thickness of PVA layer,the failure mode turns to plastic and the specimens relatively tend to keep in one piece.Finite element simulation for impact experiment of layered fiber-reinforced cementitious composite was performed using the ANSYS/LS-DYNA numerical software and the parameters taken according to the HJC model.The simulation results and the experimental results show similar tendency.