钢渣混合土基层材料干缩及抗冻性能研究

Investigation on Drying Shrinkage Performance and Frost Resistance for Steel Slag Mixed Soil Base Material

为了解钢渣混合土基层材料在环境作用下的响应特性,分别以失水率、干缩应变、干缩系数和冻融质量损失率、冻融残留强度比为指标,开展了干缩和冻融循环试验研究。研究发现,随着钢渣占比的增加,钢渣混合土28 d干缩系数、冻融质量损失率均有所减小,冻融残留强度比先增后减,在钢渣占比50%(质量分数)时达到峰值96.1%,说明合适的钢渣占比既能抑制钢渣混合土的干缩,又赋予其较好的抗冻性能;随着水泥掺量的增加,28 d干缩系数、冻融残留强度比增加,冻融质量损失率减小,表明水泥掺量的增加不利于钢渣混合土的干缩性能但有利于其抗冻性能;土壤固化剂的掺入能改善钢渣混合土的干缩和抗冻性能。SEM分析表明,钢渣占比为50%、水泥掺量为5%配合比的钢渣混合土结构更紧密,8次冻融循环后整体性更好。通过对比不同基层材料的干缩系数和冻融残留强度比发现,钢渣混合土的干缩性能劣于水泥稳定碎石但优于水泥石灰稳定土,抗冻性达到甚至超过水泥稳定碎石。

The dry shrinkage and freeze-thaw cycle tests were conducted to discover the response characteristics of steel slag mixed soil base material under environmental conditions,the dry shrinkage strain,water loss rate,dry shrinkage coefficient,freeze-thaw mass loss rate and BDR were used as indicators,respectively.It is found that the 28 d dry shrinkage coefficient and freeze-thaw mass loss rate decrease,and BDR increases first and then decreases with the increase of steel slag proportion.It exhibits peak value of 96.1%when steel slag proportion is 50%(mass fraction),indicating that the appropriate steel slag proportion could not only restrain the dry shrinkage of steel slag mixed soil,but also endow it with better frost resistance.With the increase of cement dosage,the 28 d dry shrinkage coefficient and BDR increase,and the freeze-thaw mass loss rate decreases,which indicates that the increase of cement dosage is harmful to the dry shrinkage performance of steel slag mixed soil but is beneficial to its frost resistance.It is also found that soil curing agent can improve the drying shrinkage performance and frost resistance of steel slag mixed soil.SEM investigation implied that the steel slag mixed soil with 50%steel slag proportion and 5%cement dosage exhibits a closer structure and better integrity after 8 freeze-thaw cycles.By comparing the drying shrinkage coefficient and BDR of different base materials,it is found that the dry shrinkage performance of steel slag mixed soil is inferior to that of cement stabilized macadam,but is superior to that of cement lime stabilized soil,and the frost resistance reaches or even exceeds cement stabilized macadam.