固定掺量聚丙烯纤维对水泥砂浆力学及干缩性能影响OA

To address the issue of durability degradation caused by through cracks due to drying shrinkage in cement-based materials,a systematic study was conducted on the effects of different lengths of polypro-pylene fibers(6 mm,9 mm,12 mm)and their combinations on the mechanical properties and drying shrinkage behavior of cement mortar under the condition of a fixed mass content(1.0%).The microscopic mechanism was analyzed using scanning electron microscopy(SEM).The results showed that the incorpora-tion of polypropylene fibers significantly improved the mechanical and drying shrinkage properties of the mortar.When 9 mm fibers were incorporated alone,the 28-day flexural strength of the mortar reached 7.5 MPa,an increase of 22.95%compared to the control group.The 28-day compressive strength of the mortar in the three-length hybrid group was 36.06 MPa,an increase of 19.21%compared to the control group.The combination of three-length fibers effectively suppressed drying shrinkage,with a shrinkage rate of 0.123 3%at 28 days,a reduction of 16.52%compared to the control group.SEM observations revealed that sin-gle-length fibers mainly enhanced crack restraint through interfacial bonding,while three-length fibers formed a three-dimensional network structure within the matrix,synergistically improving the comprehensive performance of the mortar