烧结法赤泥-沥青粉固化剂稳定粉土的路用性能研究

为解决黄河冲积平原地区粉土粘聚力低、水稳定性差等工程应用问题,采用烧结法赤泥和基质沥青为主材制备粉土固化剂(RAC)对粉土进行综合稳定。按5%水泥优选掺量并附加0,2,4,6,8% RAC成型稳定粉土试件,经过标准养护、浸水软化、循环加热、低温冻融、高温自愈等特定试验条件后,进行3d、7d和28d龄期的抗压强度与压缩模量试验,对比分析不同掺量RAC稳定粉土路用性能的变化规律。采用扫描电镜(SEM)分别观察粉土、水泥稳定粉土和RAC稳定粉土的微观结构形貌和孔隙特征,进而探讨固化稳定机理。结合实体工程的应用实践对RAC稳定粉土的路用性能进行测试分析与验证。结果表明：与单掺水泥相比,RAC稳定粉土具有良好的力学性能,2,4,6,8%RAC稳定粉土标准养护3d强度分别提高110%,146%,156%,161%,28d龄期浸水强度损失率均小于20%；当RAC掺量高于4%时,循环加热5次以上可使稳定粉土的强度增长超过140%,低温冻融强度损失率小于15%；试件加载至90%极限荷载,循环加热5次后,2,4,6,8%RAC稳定粉土强度变化率分别是-8.3%,-2.3%,+8.0%,+12.9%。SEM图像显示RAC稳定使粉土形成密实的胶结凝聚体和均匀分布的孔径小于1μm非连通微孔结构,有利于稳定粉土水稳定性和抗冻性的提高；高温条件下沥青组分发生湿润粘结包裹粉土颗粒及水化产物,同时加速扩散填充内部孔隙和微裂缝,实现土体的损伤修复和结构补强。实体工程中RAC稳定粉土结构层取芯测试抗压强度为1.7MPa,压缩模量为1360MPa,路面弯沉为18~23(0.01mm),未出现裂缝、坑槽、松散等损坏现象。

Study on Road Performance of Stabilized Silt with Sintering Red Mud-asphalt Powder Curing Agent

In order to solve the engineering application problems such as low cohesion and poor water stability of silt in the alluvial plain of the Yellow River, used sintering red mud and matrix asphalt as the main materials to prepare red mud-asphalt powder curing agent (RAC) to comprehensively stabilize the silt. According to the optimum dosage of 5% cement and adding 0%, 2%, 4%, 6% ,8% RAC to form stable silt specimens, conducted the compressive strength and modulus tests at 3d, 7d, 28d ages after standard curing, immersion softening, cyclic heating, low-temperature freeze-thaw and high-temperature self-healing methods, compared and analysed the change rule of road performance of stabilized silt with different dosage of RAC. Used scanning electron microscope (SEM) to observe the microstructure and pore characteristics of silt, cement stabilized silt and RAC stabilized silt, and then to discuss the mechanism of solidification and stabilization. Combined with the practical application of entity engineering, test and verify the road performance of RAC stabilized silt. The results show that