| With the acceleration of the pace of socialist modernization in China,civil engineering materials are also constantly toward the development of new,diversified,complex and green in order to meet people’s growing yearning for a better life.The emergence of new building materials not only proves their inherent superiority,but also an important way to solve the defects of existing materials.It is one of the main ways to achieve high performance of materials.They are in combination with concrete in both macro and micro combination,it has become the new research subject in the strength and durability of concrete.This paper also lays a foundation for the research and application of calcium sulphate whisker reinforced materials in cement-based materials.In this paper,different dosage of basalt fiber and calcium sulfate whisker was used as a variate.Based on macro and micro fiber composite optimization,the effect of different dosage of basalt fiber and calcium sulfate whisker on the fresh concrete slump and the effect of the calcium sulfate whisker on cement setting time are explored.Three mechanical indices and failure patterns were analyzed under different mechanical parameters which include concrete compressive strength,splitting tensile strength and flexural tensile strength;The chloride ion penetration resistance of concrete was tested.The microcosmic level and comprehensive mechanical properties of concrete materials were analyzed,and the action mechanism of the combination of basalt fiber and calcium sulfate whisker was expounded.The results showed that:(1)The addition of basalt fiber and calcium sulfate whisker will lead to the increase of cohesion of fresh concrete,and the slump of concrete will gradually decrease.when the mass content of calcium sulfate whisker varied from 0% to 4%,the consistency of cement paste increased with the increase of whisker content,and the effect of whisker cement setting time was firstly shortened and then lengthened.(2)When the volume content of single mixed basalt fiber is 0.2%,the compressive strength,splitting tensile strength and flexural tensile strength of ordinary concrete can be improved,but the improvement effect was not obvious.The single mixed calcium sulfate whisker can improve the compressive strength and flexural tensile strength of concrete,and the best increase rates are 16.6% and 9.8%,respectively,but has no obvious effect on the splitting tensile strength of concrete.The composite mechanical properties of concrete can be optimized by adding basalt fiber and calcium sulfate whisker together compared with adding single fiber or whisker.(3)The effect of the single mixed basalt on the chloride ion permeability is not obvious.Single calcium sulfate whisker can significantly improve the chloride ion penetration resistance of ordinary concrete.The optimal content of calcium sulfate whisker was 2%,and the chloride ion diffusion coefficient was 36.8% higher than that of ordinary concrete.A suitable amount of complex basalt fiber and calcium sulfate whisker can improve the chloride ion permeation resistance of concrete,and the maximum increase rate is 33.7%,the contribution is mainly from calcium sulfate whisker(4)The single mixed calcium sulfate whisker reduces ratio of the flexural strength to compressive strength and tensile strength to compressive strength of ordinary concrete,and increases the brittleness of concrete.The addition of basalt fiber can reduce the brittleness of concrete to a certain extent.The addition of macroscopic and microscopic fibers played a good strengthening effect on improving the overall mechanical properties of concrete.The microstructure test results showed that the basalt fibers can be staggered on the surface and inside of the matrix,filling the internal holes and bridging the fracture area.When the content of basalt fiber is high,the uneven dispersion of basalt fiber will also reduce the macroscopic mechanical properties and durability of concrete.Calcium sulfate whiskers can strengthen the bond between the aggregate and the hardened slurry and make the concrete a dense continuum. |
