冻融与盐蚀耦合作用下钢纤维–玄武岩纤维再生混凝土劣化机理研究
Deterioration Mechanism of Steel Fiber-Basalt Fiber Recycled Concrete under the Coupling Action of Freeze-Thaw and Salt Erosion

在再生混凝土中加入钢纤维和玄武岩纤维能增强抗冻性能和抗硫酸盐侵蚀。通过对再生骨料进行超声清洗，基于冻融循环–硫酸盐耦合试验测定了试件的质量损伤、相对动弹性模量、抗压强度损失。讨论了钢纤维和玄武岩纤维对再生骨料工作性能的影响，研究了试件冻融循环50次、100次和150次的应力–应变曲线。基于纤维增加理论，提出了复合材料效应，深入探讨了混凝土受压破坏机理。结果表明：钢纤维和玄武岩纤维掺入再生骨料，会降低再生混凝土的工作性能；在不受冻融循环影响时，钢纤维–玄武岩纤维再生混凝土比对照组再生混凝土抗压强度增强13.27%。经过150次冻融循环后，SBFRCC-3的强度损失为22.63%，再生混凝土强度损失为31.62%；当钢纤维掺量为1.5%时，通过对钢纤维–玄武岩纤维再生混凝土的质量损失、相对动弹性模量、抗压强度损失数据分析后，SBFRCC-3的抗冻性和抗硫酸盐侵蚀性能均优于普通再生混凝土；钢纤维–玄武岩纤维再生混凝土中钢纤维起到支撑作用，玄武岩纤维则是阻止裂缝的延展。
The addition of steel fibers and basalt fibers to recycled concrete can enhance frost resistance and sulfate attack resistance. The recycled concrete was prepared after ultrasonic cleaning of recycled aggregate. The mass damage loss, relative dynamic elastic modulus loss and compressive strength loss of the specimens were determined based on the freeze-thaw cycle-sulfate coupling test. The effects of steel fibers and basalt fibers on the performance of recycled aggregates were discussed, and the stress-strain curves of the specimens were studied for 50, 100 and 150 freeze-thaw cycles. Based on the fiber increase theory, the composite material effect is proposed, and the compression failure mechanism of concrete is discussed in depth. The results show that the steel fiber and basalt fiber mixed with recycled aggregate will decrease the slump of recycled concrete; when not affected by freeze-thaw cycles, the compressive strength of steel fiber-basalt fiber recycled concrete is 13.27% higher than that of the control group recycled concrete. After 150 freeze-thaw cycles, the strength loss of SBFRCC-3 was 22.63%, and the strength loss of recycled concrete was 31.62%. The frost resistance and sulfate corrosion resistance of SBFRCC-3 are better than ordinary recycled concrete after analysis of the loss data of dynamic elastic modulus and compressive strength; the steel fiber plays a supporting role in recycled concrete. In addition, basalt fiber plays a role in preventing crack development.