Study On Properties And Reinforcement And Toughening Mechanism Of Cement-based Fiber Toughened Materials

Mortar often exhibits certain performance defects in actual engineering use,which adversely affects the construction(structure).A large number of studies have found that the addition of fiber to the mortar can improve the toughness of the mortar product and inhibit the development of cracks.This kind of composite material is composed of cement mortar as the matrix and various fibers as the reinforcing phase.It is a new type of composite building material.Based on the previous research,this paper uses the fully automatic cement load bending and compression tester,split hydraulic jack 10 T,ZNLBS micro S-type tensile force sensor to carry out the bending test of fiber cement mortar material.The test piece is made up of test pieces made of 10 mm,15mm,20 mm and 25 mm long,and the mass fraction of the blended fish is 0.1%,0.15%,0.2%,0.25%.The age is 3 days,7 days and 28 days.The load-deflection curve obtained by the test was analyzed to study the effect of fiber on the mechanical properties of cement mortar material.Then,the section of the test piece subjected to the flexural test was sliced and subjected to electron microscopy.The influence of fiber on the cement-based material was analyzed by microscopic observation.Then a simplified anti-folding theory analysis model is established to predict the performance of fiber-reinforced cement-based materials under four-point bending test(FPBT).The theoretical results obtained verify the rationality of the test results.Finally,the four-point bending beam crack propagation model was established by Abaqus software.The theoretical elastic modulus of the test piece was used to change the material properties of the test block.The loading method of the test block was simulated during the test.Finally,A load-deflection curve is obtained.The results show that the numerical calculation and theoretical analysis and the experimental results obtained the peak of the flexural strength can be well matched,but in the actual test,the fiber presents a 3D chaotic distribution in the matrix,and the interaction between the fiber and the matrix is very The complexity of the anti-folding softening section is not good.This also illustrates the bridging effect of the fiber on the substrate from the side,which is the key to improving the toughness of the matrix.The research results have certain value for the analysis of the performance of fiber reinforced cement composites.