Steel-polypropylene hybrid fiber high performance cement-based composites: Mechanical properties, microscopic mechanisms, and carbon emission evaluation

To overcome the problems of steel fiber reinforced high performance cementitious composites (SF/HPCC), such as mixing difficulties, self-weight, high cost and high carbon emissions. The polypropylene fiber (PPF) was selected to substitute steel fiber (SF) in equal volume to explore the rule of PPF replacement rate on workability, compressive strength and split tensile strength of SF-PPF/HPCC, and the mechanism of the effect of the substitution ratio of PPF for SF on the mechanical properties of SF-PPF/HPCC was revealed. Finally, the carbon emission and economic analysis of SF-PPF/HPCC were evaluated. The results showed that PPF substitution of SF improves the workability of SF-PPF/HPCC, Compared to SP0, the SP10, SP15, SP20, SP30, and SP40 showed an increase of 4.34 %, 6.52 %, 10.87 %, 13.04 %, and 13.04 % in slump, and an increase of 1.25 %, 2.5 %, 5 %, 6.25 %, and 7.5 % in slump flow, respectively. For the mechanical properties, when the replacement of SF by PPF was 20 % (SP20), the compressive strength decreased by 6.54 % and the splitting tensile strength increased by 16.82 % compared with SP0. From the quantitative analysis of microscopic morphology and microscopic parameters, the increase of the substitution rate of PPF weakened the cutting effect of SF, so that the particles tended to be elongated and the pore size increased. However, the reasonable blending of PPF and SF can make the size of particle and pore tend to be fine and improve the macroscopic properties of SF-PPF/HPCC. Replacing SF with PPF can reduce CO₂ emission, lower the social cost of CO₂ emission, and lower the production cost of SF-PPF/HPCC, which was an effective strategy to achieve low-carbon and low-cost production, and was of great significance to promote its application in the engineering field.