矿渣+粉煤灰+聚丙烯酰胺固化硫酸盐渍土的物理力学性能

Physical and mechanical properties of saline soil stabilized by combined slag,fly ash and polyacrylamide

硫酸盐渍土广泛分布于新疆地区,其盐胀性常常导致道路的开裂破坏。针对新疆地区硫酸盐渍土,采用粉煤灰+矿渣+聚丙烯酰胺(polyacrylamide,简称PAM)联合改性土的方法,通过盐胀试验、界限含水率试验、p H/总溶解固体/电导率试验、硫酸根离子浓度测试、无侧限抗压强度试验及冻融循环试验,研究了固化土的力学和物理化学性能。在此基础上,通过扫描电镜(scanning electron microscope,简称SEM)试验分析了其改性机制和微观结构特征。结果表明:粉煤灰+矿渣+聚丙烯酰胺的无机有机相结合的方式不仅可以有效抑制硫酸盐渍土的盐胀量,而且可以改善盐渍土的力学性能、塑性及抗冻性。综合考虑经济性和适用性,当联合固化材料掺量达到15%,且PAM掺量为2%时最优,其抑制盐胀效果最佳;土体结构性和整体性变强,固化土7 d无侧限抗压强度达到993 kPa,相较天然土提高了3倍;土体抗冻融性得到明显的改善。

Sulfate saline soils are widely distributed in Xinjiang,where salt expansion often leads to road cracking and damage.This study investigated the effectiveness of a method that combines fly ash,slag,and polyacrylamide(PAM)in treating saline soils.Various tests,including salt expansion,boundary moisture content,pH,total dissolved solids(TDS),electrical conductivity(EC),sulfate ion concentration,unconfined compressive strength,and freeze-thaw cycle tests,were conducted to evaluate the mechanical and physicochemical properties of the solidified soil.Moreover,scanning electron microscopy(SEM)was utilized to explore the enhancement mechanism and microscopic features.The results indicate that the inorganic-organic combination of fly ash,slag,and polyacrylamide effectively suppresses salt expansion in sulfate saline soil,enhancing its mechanical properties,plasticity,and frost resistance.Considering economic feasibility and practicality,the optimal ratio was determined:a mixture of fly ash,slag,and PAM at 15%,with PAM at 2%.Under these conditions,the treatment exhibits the most efficient inhibition of salt expansion and improves structural integrity.The 7-day unconfined compressive strength of the treated soil reaches 993 kPa,three times higher than that of natural soil.Additionally,the soil demonstrates a significant enhancement in freeze-thaw resistance.