Study On Properties Of Hybrid Fiber Reinforced Cement-based Materials

Cement-based materials are currently the most widely used construction materials.Cement-based materials are more brittle,have lower tensile strength and strain capacity,and will affect the overall load-bearing capacity,durability and normal use function of the structure during long-term use.The defects in the performance of cement-based materials mentioned above should be improved in some way.Incorporating fibers into cement-based materials to form composites is one of the most effective methods to improve the performance of cement-based materials.In this study,a composite material composed of basalt fiber,polypropylene fiber,and portland cement was used as the object,while maintaining the mixing ratio of the cement-based material,the effects of fiber types,lengths,and amounts on the mechanical and durability properties of cement-based composites were studied.The specific length of the basalt fiber is 6mm?9mm?12mm?18mm,and the fiber content is 1.2 kg·m-3?2.4 kg·m-3?3.6 kg·m-3?4.8 kg·m-3;the length of polypropylene fiber is 6mm?9mm?12mm?18mm,and the fiber blending amount is 0.6 kg·m-3?0.9 kg·m-3?1.2kg·m-3?1.5 kg·m-3.The test clarifies the change of performance parameters of hybrid fiber reinforced cement composites by performing performance tests on compressive strength,flexural strength,water absorption,and acid corrosion resistance of single-fiber and hybrid fibers.The results show:1.The single-doped basalt fiber has little effect on the compressive strength of the composite material;the early flexural strength of the composite material increases with the increase of the fiber content,within a certain content range,the flexural strength of the composite material basically remains with the fiber length increases and the trend of increasing;the bending ratio of the composite material increases with the increase of the fiber content,and the bending ratio of the composite material decreases with the increase of the fiber length.When the fiber length is constant,as the fiber content increases,the water absorption coefficient of the composite material decreases first and then increases;when the fiber content is constant,as the fiber length increases,the water absorption coefficient of the composite material decreases first and then increases.As the number of days increases,the strength retention rate of the composite material gradually decreases;when the fiber length is constant,as the fiber content increases,the strength retention rate of the composite material increases first and then decreases;when the fiber content is constant,the strength retention rate of the composite material increases first and then decreases with the increase of the fiber length.2.The effect of single-doped polypropylene fibers on the compressive strength of the composite material is negligible;the flexural strength and compression ratio of composites increase with the increase of fiber content,in a certain range,the flexural strength and bending strength of composite materials increase with the increase of fiber length;with the increase of fiber content,the bending ratio of composite materials basically increased.When the fiber content is less than 1.2 kg·m-3,as the fiber length increases,the folding ratio of the composite material gradually increases;when the fiber content is higher than 1.2 kg·m-3,as the fiber length increases,the bending ratio of the composite material decreases first and then increases.When the fiber length is constant,as the fiber content increases,the water absorption coefficient of the composite material decreases first and then increases;when the fiber content is constant,as the fiber length increases,the water absorption coefficient of the composite material gradually decreases.When the fiber length is 12mm,the strength retention rate of the composite material increases first and then decreases with the increase of the fiber content;when the fiber content is 1.5 kg·m-3,the strength retention rate of the composite material increases as the fiber length increases.Gradually reduce the trend.3.Basalt and polypropylene fiber composites have improved mechanical properties and durability to a certain extent,but the incorporation of fibers has a small effect on the compressive strength of the composite material.When the polypropylene fiber length is 6mm-12mm,the flexural strength of the test block is better,when the fiber length is 6mm-9mm,the flexural strength of the test block is better;when the basalt fiber content is 3.6 kg·m-3-4.8 kg·m-3,the flexural strength and compression of the test block are better.The polypropylene fiber has a better impermeability to the test block within the range of 6mm-9mm;when the basalt fiber content is in the range of 1.2 kg·m-3-2.4 kg·m-3,the test block has a lower water absorption rate and better impermeability.The increase of polypropylene fiber length has a negative impact on the acid corrosion resistance of the composite as a whole;for the flexural strength of the acid corrosion resistance test block,the optimum range of the basalt fiber content is 1.2 kg·m-3-2.4 kg·m-3.