硫酸钠环境下气泡混合轻质土的抗干湿性能研究

Study on Resistance to Dry-wet Cycles of Air-foam Treated Light Soil under Sodium Sulfate Environment

制备了不同密度的气泡混合轻质土试样,研究了硫酸钠环境下气泡混合轻质土的抗干湿循环性能,重点分析了气泡混合轻质土的体积、密度和强度随浸泡时间和干湿循环次数的变化规律。试验结果表明,气泡混合轻质土在硫酸钠溶液和干湿循环共同作用下,硫酸钠晶体的析出和溶解以及钙矾石等物质所致的试样膨胀与表层剥落,均会对试样的体积产生显著的影响,较高的初始强度和孔隙率对于试样体积稳定性是有利的;试样在膨胀、剥落前的密度随干湿循环次数变化曲线相互平行乃至重合,试样在膨胀、剥落后的密度变化曲线相互交错;硫酸钠侵蚀试样生成钙矾石等物质,致使试样在干湿循环作用下更易产生裂缝,选用较高初始强度和较低水泥用量的试样可有效控制这一影响。

Air-foam treated light soil samples of different densities are prepared to study the resistance to dry-wet cycles under sodium sulfate environment. The influence of sodium sulfate solution and the dry-wet cycles on the volume,density and strength of the samples is studied. The experimental results show that,under the effect of sodium sulfate solution soaking and dry-wet cycles,the precipitation and dissolution of sodium sulfate crystals and the expansion and surface peeling of samples caused by calcium alum and other substances have a significant impact on the volume of samples. High initial strength and high porosity are beneficial to volume stability. The density variation curves of samples before expansion and exfoliation are parallel to and even coincide with each other. Calcite and other substances are produced when the samples are eroded by sodium sulfate,making the samples more prone to cracking under the effect of dry-wet cycles. The influence can be effectively controlled by selecting samples with high initial strength and low cement content.