Influence of basalt fiber and polypropylene fiber on the mechanical and durability properties of cement-based composite materials

Abstract

To boost the mechanical strength and endurance quality of cement-based composites, basalt fiber and polypropylene fiber have been included cement-based composites in a single-doped and mixed manner, respectively. Through the tests of flexural strength, compressive strength, drying shrinkage and freeze-thaw cycle, the mechanics properties and endurance quality of cement-based composites with different fiber contents were analyzed. Scanning electron microscopy and a mercury intrusion test were used to compare and study the microstructure and pore structure properties of cement-based composites. The results indicate that the improvement of compressive strength for cement-based composites by single adding basalt, polypropylene fiber and mixed addition of two kinds of fibers is not obvious, but improving the flexural strength of composites by single addition of fiber and 1:1 mixing in a certain dosage range is effective. Among them, 1:1 mixed fiber shows a better advantage superposition effect, which shows better enhancement and toughening effect on composites. Fiber single doping and 1:1 mixing can reduce the Drying shrinkage and mass loss rate of the composites within a certain range, and enhance the composites' ability to resist Drying shrinkage and freezing. Based on the comprehensive mechanical properties and durability tests, it is recommended that the content range of the two fibers mixed with 1:1 is 0.4 %–0.6 %. Both basalt fiber and polypropylene fiber can be closely combined with the cement matrix, and randomly distributed in the composite material to form a network structure, which has the function of series skeleton, effectively inhibits the generation and expansion of cracks in the composite material, and improves the microstructure of the composite material. Both basalt fiber and polypropylene fiber can reduce the harmful pores and multi-harmful pores of the composite material, and transform them into harmless pores and less harmful pores, refine the internal pore structure of the composite material, and improve its compactness. The two kinds of fibers are randomly distributed to form a network structure, which refines the large pore size inside the composite material and blocks the connected pores, and the basalt fiber is refined to fill the interface between the polypropylene fiber and the cement matrix, so that the composite material is more compact, thereby significantly improving the mechanical properties and durability of the composite material.