Experimental Study And Numerical Simulation Of Mechanical Properties Of Twisted Basalt Fiber Bundle Reinforced Concrete

With the rapid development of the economy in China,the traffic volume undertaken by bridges is increasing,and at the same time,some problems arise,such as cracking of concrete,damage to expansion joints,water seepage on pavements,and serious damage to bridge decks.Under the action of overload and dynamic load,the concrete layer of the long bridge is prone to cause cracks in key parts of the bridge.Working under abnormal conditions,the accumulated durability over time will deteriorate,and fatigue damage is inevitable.Studies have shown that adding fibers to concrete can improve the crack toughness and durability of concrete and increase the service life of the structure.Basalt fiber(BF),which has emerged in recent years,is a material with high mechanical properties and environmental protection.The basalt fiber reinforced concrete(BFRC)prepared from it has high application value.However,the chopped basalt fiber has a great influence on the fluidity of the concrete,and agglomeration is easy to occur during mixing,which brings inconvenience to the construction.In this paper,a twisted basalt fiber bundle is prepared by improving the preparation process of basalt fiber and used to reinforce concrete materials;through the two methods of experiment and simulation,the performance of chopped basalt fiber and twisted basalt fiber bundle concrete is compared and studied.First,five groups of chopped basalt fiber reinforced concrete mechanical properties tests with different volumes were conducted.The test results show that with the increase of the fiber content,the fluidity of the mixture gradually decreases;the addition of fiber reduces the compressive strength of the concrete,and the maximum 28 d split tensile strength and flexural strength are increased by 4.22%,3.6%;Secondly,the mechanical properties of 6 groups of twisted basalt fiber bundle concrete with different volumes and different diameters were tested,and the same volume content(0.2%)of chopped basalt fiber and twisted basalt fiber bundleconcrete were compared.Studies have shown that the addition of twisted basalt fiber bundles can significantly enhance the splitting tensile strength and flexural strength of concrete.Under the same dosage(0.2%),twisted basalt fiber bundles have better effects on the mechanical properties of concrete;At the same time,through the comparison of the fluidity of the mixture,it is found that twisted basalt fiber bundle has a smaller effect on the fluidity of the concrete than chopped basalt fiber.Then,six groups of twisted basalt fiber bundle concrete with different volume and different diameters were tested for fracture performance.The study found that twisted basalt fiber bundles can significantly enhance the fracture properties of concrete.With the increase of the fiber content,the peak load,initiation toughness,and instability toughness gradually improved;among the three twisted basalt fiber bundle diameters of 0.2mm,0.5mm,and 0.8mm,the 0.2mm diameter twisted basalt fiber bundle affects the fracture performance of concrete.The enhancement effect is the best;Finally,based on the flexural test data of 0% and 0.2% twisted basalt fiber bundle concrete,the numerical simulation of the flexural test of twisted basalt fiber bundle concrete was carried out using ABAQUS finite element software,and the simulation results were compared with the test to verify validity and accuracy of numerical simulation;by simulating the uniaxial compression test of twisted basalt fiber bundle concrete,the effects of twisted basalt fiber bundle dosage,length and diameter on the compressive strength of concrete were studied.The results show that the compressive toughness gradually increases with the increase of the admixture;the change in length has no obvious effect on the compressive strength;when the admixture is a certain amount,appropriately increasing the fiber length-to-diameter ratio can increase the compressive strength of the concrete.