含硫酸盐的半刚性基层材料干缩性能试验研究

Experimental study on the dry shrinking performance of the semi-rigid material intensity at the basic level of sulfate salty soil

本文介绍了掺加硫酸钠的石灰土、水泥土和二灰土四种半刚性基层材料的室内干缩试验方法及步骤,得出了在最佳含水率下这四种盐渍化的半刚性基层材料的干燥收缩与失水率的关系曲线.试验结果显示:干燥引起的水分蒸发使硫酸钠从孔隙溶液中结晶析出,所产生的结晶膨胀部分抵消了半刚性材料的失水收缩,因而可减小半刚性基层材料的干缩裂缝,并推荐了四种半刚性基层材料各自的最佳Na2SO4含量.在失水初期,随着失水率的增大,干缩应变急剧增大,与其相应的干缩系数先急剧增大,而后又骤然减至较小,至失水率增大至某一数值之后,随着失水率的继续增大,干缩应变趋于缓慢增大,与其相应的干缩系数缓慢减小;在失水率或曝露时间相同的情况下,干缩应变由大到小的排序为:石灰稳定土>水泥稳定土>二灰稳定土(10∶15∶75)>二灰稳定土(10∶45∶45),干缩系数由大到小的排序为:水泥稳定土>石灰稳定土>二灰稳定土(10∶15∶75)>二灰稳定土(10∶45∶45).

This article describes the experiment methods and the steps of the laboratory dry shrinkage in the semi-rigid base materials of the lime soil,cement soil and lime-fly ash with sulfate.The relation curves of the dry shrinkage changes with water loss rate of the solemnization semi-rigid base material at optimum water content have been drawn.The experimental results show that the sodium sulfate crystallization from the pore solution for the water evaporation caused by drying and the expansion of the crystallization offset the dehydration shrinkage in the semi-rigid base materials.Thus it reduces the semi-rigid base material shrinkage cracks.And we recommend that the optimum sodium sulfate content for each material.In the initial stages of water loss,the dry shrinkage strain and the dry shrinkage coefficient increased rapidly as the water loss rate increased.Both the dry shrinkage strain,and corresponding shrinkage coefficient would slow down.Under the same circumstances of the water lossrate or exposure time,the order of descending for the dry shrinkage strainis： the lime stabilized soil〉 the cement stabilized soil〉 the lime-fly ash stabilized soil（10∶15∶75）〉 the lime-fly ash soil（10∶45∶45）.And the order of descending for the dry shrinkage coefficient is： the cement stabilized soil〉 the lime stabilized soil〉 the lime-fly ash stabilized soil（10∶15∶75）〉the lime-fly ash soil（10∶45∶45）