为解决明董高速公路浸水路基水稳定性不足问题,提高路基承载能力,将工业固废电石渣粉(CS)与煤矸石粉(CG)作为稳定材料用于浸水路基土稳定。对掺量分别为5%、10%和15%及CS-CG配比分别为0∶100、30∶70、50∶50、70∶30和100∶0的稳定土进行无侧限抗压强度试验、干湿循环试验、浸水试验、pH值试验、X射线衍射试验、扫描电子显微镜试验、压汞试验,分析CS-CG稳定土力学性能及水稳定性,研究水影响下稳定土的微观结构特征,揭示其强度形成机理。结果表明:CS-CG-10%-(70∶30)的28d龄期稳定土强度较大为5.87MPa,6次干湿循环试验后的强度为4.77MPa,对比4%水泥稳定土水稳定性占优,CS-CG稳定土具有良好的承载能力和水稳定性;浸水30d后强度随着CS占比增大而增大,CS-CG-10%-(100∶0)和CS-CG-10%-(70∶30)强度分别为6.29和5.74MPa,相比未浸水时分别增加了54.0%和48.5%,水稳定性良好;pH值随着CS-CG掺量及CS占比增加而增大,但随着干湿循环次数的增加pH值略微减小,CS-CG-10%-(70∶30)稳定土的pH值为9.71,呈弱碱性,对环境影响较小;掺加CS-CG后稳定土中产生了大量的C-(A)-S-H凝胶、Ca(OH)2及钙矾石晶体等水化产物,改善了孔隙结构,稳定土强度增加,干湿循环作用下水化产物进一步增加但孔径有所增大。研究表明CS-CG稳定土具有良好的承载能力和水稳定性,考虑到环境因素pH值不宜过高,建议CS-CG最佳掺量为10%,最佳配比为70∶30。

A mixture of carbide slag (CS) and coal gangue powder (CG) was utilized as the stabilizer for the roadbed soil of the soaked subgrade of the Mingdong Expressway in order to increase the water stability and bearing capacity of the subgrade. The dosages of stabilizer were 5%, 10% and 15%, and the quantity ratios of CS and CG were 0∶100, 30∶70, 50∶50, 70∶30 and 100∶0. Tests of unconfined compressive strength (UCS), dry-wet cycles, water immersion, pH value detection, X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) were conducted to evaluate the mechanical properties, water stability and microscopic characteristics of the CS-CG stabilized soil. The results show that the UCS value of CS-CG-10%-(70∶30) stabilized soil was 5.87 MPa after curing for days, and the UCS was decreased to 4.77 MPa after dry-wet cycles. It was evident that the bearing capacity and water stability were good. With increasing CS percentage, the UCS of the stabilized soil after days’ immersion increased. The UCS of CS-CG-10%-(100∶0) and CS-CG-10%-(70∶30) stabilized soil were 6.29 and 5.74 MPa respectively. The pH value increased with an increase of CS-CG dosage and CS proportion, but decreased slightly as the dry-wet cycles increased. The pH value of CS-CG-10%-(70∶30) stabilized soil was 9.71. After adding CS-CG, a large number of hydration products such as C-(A) -S-H gel, Ca (OH) crystal and ettringite were produced in the stabilized soil, which improved the pore structure and increased the UCS. With more dry-wet cycles, the hydration products increased, which was benefit for the properties of the stabilized soil, but the pore diameter also increased. It can be seen that CS-CG stabilized soil has good bearing capacity and water stability. Considering the effects on the environment, the pH value of stabilized soil should not be too high, so it is recommended that the best dosage of CS-CG stabilizer is 10%, and the best ratio of CS-CG is 70∶30.