Environmental effects on durability of soil stabilized with recycled gypsum
Environmental effects on durability of soil stabilized with recycled gypsum
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DOI：
10.1016/j.coldregions.2010.12.004
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发表时间：
2011-05
影响因子：
4.1
通讯作者：
Aly Ahmed;K. Ugai
中科院分区：
文献类型：
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作者：
Aly Ahmed;K. Ugai
利用石膏废石膏板回收的石膏用于地面改良最近在日本开始，但在世界各地并不普遍。因此，有必要探讨环境条件对再生石膏稳定土的性能和耐久性的影响。由于石膏的溶解性，这在寒冷和多雨地区（如日本）尤为重要。本文通过综合试验研究了冻融循环和干湿循环等环境因素对再生石膏固化土耐久性的影响。为此，使用了四种不同含量的回收石膏，范围从0到20%。采用0 ~ 5%的四种不同水泥掺量作为固化剂，优化水泥掺量，使其足以防止溶解并提高耐久性。为研究环境因素对稳定土耐久性的影响，采用最大干容重击实圆柱形试件，恒温恒湿养护7 d。随后，样本进行不同数量的冻融和干湿循环。然后测试它们的抗压强度、土壤重量损失和体积变化。结果表明，随着冻融循环次数和干湿循环次数的增加，固化土的抗压强度降低，累计失重增加。冻融循环对固化土耐久性的影响比干湿循环的影响更为显著。随着再生石膏和水泥掺量的增加，固化土的耐久性提高。从地基的力学性能和经济性能来看，2.5%的水泥掺量足以提高再生石膏加固土的耐久性。冻融循环和干湿循环对再生石膏固化土的体积变化影响不大。当水泥掺量为2.5%时，随着干湿循环次数的增加，强度略有增加，但随着干湿循环次数的增加，强度有所下降。仅用回收石膏而不使用任何固化剂（如水泥）稳定的土壤不耐环境条件。
The use of recycled gypsum, which is derived from gypsum waste plasterboard, for ground improvement has recently been initiated in Japan and is not widespread around the world. As such, it is essential to explore the effect of environmental conditions on the performance and durability of soil stabilized with recycled gypsum. This is especially important in cold and rainfall regions such as in Japan, due to the solubility of gypsum. This paper presents an integrated experimental study to investigate the effect of environmental factors, in terms of freeze–thaw and wet–dry cycles, on the durability of soil stabilized with recycled gypsum. For this purpose, four different contents of recycled gypsum ranging from 0 to 20% were used. Four different cement contents ranging from 0 to 5% were used as solidification agent to optimize the cement content which is adequate to prevent the solubility and improve the durability. To study the effect of environmental factors on the durability, cylindrical specimens of stabilized soil were compacted at maximum dry unit weight and cured for 7days under constant temperature and humidity. Subsequently, specimens were subjected to different numbers of freeze–thaw and wet–dry cycles. They were then tested for compressive strength, loss soil weight, and volume change. Results showed that compressive strength of stabilized specimens decreased while accumulated soil losses weight increased with the increase of both numbers of freeze–thaw and wet–dry cycles. Freeze–thaw cycles have a significant effect on the durability reduction of stabilized soil compared with the effect of wet–dry cycles. The durability of stabilized soil improved with the increase of both contents of recycled gypsum and cement. The 2.5% cement content is adequate to improve the durability of soil stabilized with recycled gypsum based on ground mechanical and economic functions. Both freeze–thaw and wet–dry cycles have insignificant effect on the volume change of soil stabilized with recycled gypsum. After using 2.5% of cement content, the strength of stabilized soil specimens increased slightly with the increase of wet–dry cycles; subsequent to that, the strength declined with increasing wet–dry cycles. Soil stabilized with only recycled gypsum and without any solidification agents, such as cement, is not durable against environmental conditions.