Multiscale Investigation On Blast Resistance Of PVA And Steel Fiber-Reinforced Concrete

As an artificial building material which has been widely used in the world,concrete has many advantages,such as high compressive strength,good durability,low cost and so on.However,its weak tensile performance and obvious brittleness make concrete behave poorly under ultimate impact load like penetration and explosion.For improving the weak tensile performance and energy dissipation property of concrete,it is an effective method to add fibers with a certain volume ratio to the concrete matrix.In the field of building materials,steel fiber and PVA fiber are widely favored by scholars because of their good material properties and strong bond with cementitious matrix.In order to respond to the call of the national scientific and technological innovation plan of the 14 th Five-year Plan,this paper,from both meso-scale and macro-scale,studied low-cost and domestic production of PVA Fiber-Reinforced Concrete(PVA-FRC)and influence of fiber orientation effect on Steel Fiber-Reinforced Concrete(SFRC);Afterwards,contact explosion tests of the two kinds of fiber-reinforced cementitious composites were carried out,and Lattice Discrete Particle Model-Fiber(LDPM-F)was introduced herein to establish the mesoscale PVAFRC and SFRC numerical model for exploring their blast resistance.The main contents of this paper are as follows:(1)Through reasonable adjustment of mix proportion,this paper developed a cost-effective PVA-FRC whose all raw materials came from China.The tested maximum tensile strain of the PVA-FRC was more than 4% and the tensile strength was about 4.0 MPa,behaving good tensile performance.By fitting and comparing with the experimental results,mesoscale PVAFRC LDPM-F numerical model was established.The numerical model accurately predicted the compression,tension and bending responses of the PVA-FRC and successfully captured the multi-cracking phenomenon of the PVA-FRC.(2)Based on the experiment and LDPM-F numerical simulation,the fiber orientation effect in SFRC was studied at multiscale.In order to study the bond properties between fiber and matrix in mesoscale,this paper proposed a double-sided inclined fiber pullout test.According to the test results,the effect of fiber orientation on the interfacial bond properties was obtained,and the bond strength between steel fiber and matrix was captured as 6.6 MPa,the value of fiber snubbing parameter was 0.4.In the macroscale study,the SFRC "dogbone" tension test was carried out and simulated.The established SFRC LDPM-F numerical model was applied to macroscopically study the fiber orientation effect on the tensile properties of SFRC.It was conclued that the SFRC tension specimens showed the highest tensile strength when fiber deflection angle was 30?,and the best ductility and toughness of the specimens were captured when the fiber deflection angle was 60?.(3)The blast-resistant performance of SFRC and PVA-FRC was studied herein through contact explosion test.Firstly,the contact explosion tests were carried out on SFRC,PVA-FRC and control PC specimens,and the damage of each specimens was recorded in detail.It was found that SFRC showed the best blast resistance at the same fiber content.At the same time,the blast-resistant performance of PVA-FRC and SFRC was simulated based on the mesoscale LDPM-F numerical model.The FRC LDPM-F blast model predicted the blast resistance of FRC materials with different fiber content.It is found that when the fiber volume ratio was less than 2%,the blast resistance of PVA-FRC was greatly degraded,while SFRC still performed good blast resistance.