Iranian Journal of Science and Technology, Transactions of Civil Engineering ( IF 1.7 ) Pub Date : 2021-03-19 , DOI: 10.1007/s40996-021-00621-y Ali M. Rajabi , Alireza Hosseini
Improvements in the strength characteristics of soil are noteworthy in geotechnical engineering. Many engineering problems emerge in silty sand soil because the silty fraction generally has low strength properties. High dispersion in such soil at a construction site illustrates the necessity of studying and surveying new methods of improvement of its strength properties. One of the methods used to improve soil strength is chemical additives. In the present research, the effects of the addition of polyvinyl acetate (PVA) and micronized calcium carbonate (MCC) on the strength of silty sand soil have been investigated. PVA and MCC were mixed with soil in different proportions (1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 5% and 6% (wt.)) for unconfined compression testing and (1%, 2%, 3% and 4% (wt.)) for direct shear strength test under different curing time (1, 7, 14 and 28 days). SEM images were acquired before and after mixing to determine changes in the properties of each sample. It was found that the addition of MCC and PVA to silty sand soil increased the unconfined compression strength (UCS) by 2.5% and 4%, respectively, comparing to untreated soil. An increase in the MCC and PVA contents decreased the UCS of the soil. It was also demonstrated that the addition of PVA more effectively improved the soil strength properties than did MCC. The addition of both of materials increased the shear strength of the soil, but this increase was greater for cohesion than for the internal friction angle. It was also demonstrated that increasing the curing time in stabilized samples of both additives increased the UCS more than 80% in the first 14 days.
中文翻译:
液态醋酸乙烯酯和微粉碳酸钙对粉质砂土强度参数的影响
在土力工程中,土壤强度特性的改善是值得注意的。由于粉质级分通常具有较低的强度特性,因此在粉质砂土中会出现许多工程问题。在建筑工地的这种土壤中的高分散性说明了研究和调查改善其强度特性的新方法的必要性。用于提高土壤强度的方法之一是化学添加剂。在本研究中,已经研究了添加聚乙酸乙烯酯(PVA)和微粉化碳酸钙(MCC)对粉质砂土强度的影响。将PVA和MCC以不同的比例(1%,1.5%,2%,2.5%,3%,3.5%,4%,5%和6%(wt。)与土混合)进行无限制压缩测试,以及(1% ,2%,3%和4%(wt。))在不同的固化时间(1、7、14和28天)下进行直接剪切强度测试。在混合之前和之后获取SEM图像,以确定每个样品的特性变化。研究发现,与未经处理的土壤相比,向粉质砂土中添加MCC和PVA分别使无侧限抗压强度(UCS)分别提高了2.5%和4%。MCC和PVA含量的增加降低了土壤的UCS。还表明,与MCC相比,添加PVA更有效地改善了土壤强度。两种材料的添加都增加了土壤的抗剪强度,但这种内聚力的增加大于内摩擦角的增加。