关键词: 水泥基复合材料, 花岗斑岩石粉, 拉伸性能, 收缩, 力学性能, 聚乙烯醇纤维

Abstract: High toughness engineered cementitious composites (ECC) have been used in large size plate and beam structures due to their excellent mechanical properties and crack control, but its further application is limited by high cost. The production process of mechanism sand will produce a large amount of rock powder, which will seriously pollute the environment if not handled properly. In order to achieve the dual objectives of reducing the cost of ECC and environmental protection, granitic porphyry rock powder high toughness engineered cementitious composites (GP-ECC) with rock powder instead of river sand was prepared, its properties were studied, and the self-shrinkage prediction model for GP-ECC was established. The results show that the GP-ECC specimens exhibit the characteristics of multi-seam cracking and strain hardening, and compressive strength and flexural strength decrease first and then increase with the increase of granite porphyry rock powder replacement rate, and the best performance is achieved when completely substituted. The 28 d tensile stress peak value reaches 4.4 MPa, the ultimate strain exceedes 4.2%, the compressive strength exceedes 50 MPa, and the flexural strength exceedes 18 MPa. The early self-shrinkage value of GP-ECC increases with the increase of rock powder replacement rate, in which the self-shrinkage value when rock powder completely replaces river sand is 3 133.3 μm/m, which is 117.3% higher than that of the benchmark specimen. So it is necessary to suppress the self-shrinkage of GP-ECC. Meanwhile, the self-shrinkage prediction model proposed in this paper can effectively predict the change of self-shrinkage of GP-ECC. The SEM test results show that the PVA fibers are uniformly dispersed in the granitic porphyry rock powder cement matrix and can work together.

Key words: engineered cementitious composite, granite porphyry rock powder, tensile property, shrinkage, mechanical property, polyvinyl alcohol fiber