Experimental Study On Inorganic Mineral Fiber Reinforced Cement Mortar

Fiber reinforcement has always been the important way and research focus of manufacturing high performance cement-based materials. For this reason, developing new fiber reinforced materials and playing performance advantages of different types of fibers are deeply significant for the research and exploration of fiber reinforced cement-based materials. And as two new kinds of inorganic mineral fiber reinforcing materials, CaCO3whiskers and basalt fibers have the cost and performance advantages that are incomparable for other common fibers.In this paper, CaCO3whiskers and basalt fibers were incorporated into the cement mortar. Through the experimental study, the improvement of whiskers on physical and mechanical properties of cement mortar was first investigated, and then the strengthening and toughening effect of basalt fibers with different length and content in mortar was discussed, after that the effect of hybrid fiber with different length on the mechanical properties of mortar was also analyzed. On this basis, whiskers were mixed into the basalt fiber cement mortar and the composite reinforcing effect of the whiskers and fibers was investigated. Finally, the performance of whisker and basalt fiber reinforced cement mortar was optimized with the use of silica fume. The main achievements are as follows:(1) When the CaCO3whisker content was10%, the fluidity of cement mortar had no significant deterioration and the harmful pores number decreased. The mechanical properties reinforcement also achieved the best results. Compared with the pure cement mortar,3d and28d compressive strength were increased by15.3%and13.0%and the flexural strength was increased by29.5%and7.2%respectively;28d split tensile strength was increased by26.2%; impact resistance was also improved to a certain degree and the impact number was increased.(2) The mechanical properties reinforcing effect of basalt fiber with different length and volume content in mortar were different. Through the comparative analysis, it can be seen that the strengthening and toughening effect of6mm fiber was most prominent. When the fiber content was0.05%,28d compressive strength was increased by3.54%; As the content was0.1%,28d flexural strength and split tensile strength were increased by8.83%and22.08%respectively, and the impact resistance has also been significantly improved. But the capacity to resist the impact load after the first crack of the specimen was enhanced. (3) Compared with the fiber reinforcement of single length, hybrid fiber with different length showed different hybrid effect. When fibers with four different length were mixed by the same content, in addition to compressive strength, flexural strength, split tensile strength and impact resistance were all improved more obviously than the fiber reinforcement with a single length under the same fiber content, which showed the best positive hybrid effect and hybrid mechanisms were also discussed.(4) When whiskers were incorporated into the basalt fiber cement mortar, the mechanical properties were improved further and the composite reinforcing mechanism was also analyzed. As the whiskers were mixed with fibers of four different length, it showed the most significant reinforcement and the reinforcing effect was superior to the combination of whiskers with6mm fibers. Under the best reinforcement conditions, compared with the pure cement mortar,28d compressive strength, flexural strength and split tensile strength were increased by7.68%,16.93%and32.26%respectively and the impact number of failure was3.85times more than the pure cement mortar.(5) Through mixing silica fume with appropriate content into the whisker and basalt fiber reinforced cement mortar respectively, the mechanical properties was further improved and the interface properties of whisker-matrix and fiber-matrix were optimized, which resulted in the improvement of reinforcing effect. When the silica fume content was5%, the reinforcing effect of whiskers and fibers was most significant. In this matrix, the increasing range of compressive and flexural strength by CaCO3whiskers were8.27%and10.96%, while the increasing range of flexural strength by basalt fibers was8.73%, but the reinforcing effect of compressive strength had little change.