Study On Mechanical Properties And Durability Of Steel Basalt Fiber Concrete

Steel basalt fiber concrete is a new type of fiber reinforced material which is formed by mixing steel fiber and basalt fiber into concrete at the same time.Steel fiber has high elastic modulus,strong tensile,bending and impact resistance.Basalt fiber not only has chemical stability,but also has certain acid and alkali resistance and high temperature resistance.Combining steel fiber and basalt fiber together can better improve various properties of concrete.However,at present,there are few experimental studies on steel basalt fiber concrete,and the research on its mixing ratio,deterioration mechanism under sulfate dry wet cycle and life prediction is not deep enough.When the fiber content is too large,the agglomeration between fibers will produce more pores,reduce the compactness of concrete and weaken the strength.In order to further improve the comprehensive performance of steel basalt fiber concrete,micro silica fume is used to replace part of cement to increase the compactness of concrete and make the interface between fiber and matrix more solid.Basalt fiber with two lengths is mixed with steel fiber and micro silica fume.Through mechanical property test,it is judged which fiber has better performance.Then simulate the complicated coastal zone environment of China,study the macro mechanical properties of steel basalt fiber concrete under the sulfate dry wet cycle environment,predict the service life based on the test data,carry out SEM and XRD microanalysis,and study the deterioration mechanism of steel basalt fiber concrete under the sulfate dry wet cycle environment in combination with the macro mechanical test data and microanalysis.The results show that:Adding a certain amount of micro silica powder into steel basalt fiber can correspondingly improve the compactness and strength of the material.The mixing effect of 12 mm basalt and steel fiber is better than 6mm basalt fiber.For the improvement of compressive strength,hfrc-5(12mm basalt fiber content 0.1%,steel fiber content 0.9%,micro silica powder replacement rate 10%)test block has the most obvious improvement,which is 34.4% higher than NC(ordinary concrete)group.For the splitting tensile strength,the hfrc-6(12mm basalt fiber content 0.1%,steel fiber content 1.1%,micro silica powder replacement rate 10%)group has the most significant effect,increasing 147.7% compared with the NC group.In terms of impact resistance,hfrc-6 group has the most significant effect.Compared with NC group,the number of initial crack impact increases by 10.4 times and the number of final crack impact increases by 19.9 times.The tensile compression ratio and impact toughness ratio of hfrc-6 test block are the highest,which are 0.174 and 19.889 respectively.In the sulfate dry wet cycle test,the corrosion solution reacts with the concrete hydration products to generate new substances,which increases the weight of each group of test blocks.The new products formed will improve the mechanical properties of the test blocks to varying degrees at the initial stage of corrosion.With the increase of the corrosion cycle,the expansive products ettringite and gypsum crystals will generate expansive stress in the cracks.When the expansive stress is greater than the ultimate tensile strength of the test blocks,the test blocks will produce larger cracks,Reduce the strength of the test block.The life prediction results show that the life of steel basalt fiber concrete under sulfate dry wet cycle is longer than that of NC group.Figure [35] Table [18] Reference [83]...