FDN-C对高塑性黏土力学特性的影响与机理分析

摘要/Abstract

摘要： 为考察萘系减水剂(FDN-C)在土体固化中的应用效果,在高塑性黏土中掺加不同用量FDN-C,与木质素磺酸钙(CA-LS)对比,分析其对压实荷载、无侧限抗压强度等力学性能的影响,并对固化处理后试样粒度、微观结构、结合水以及矿物成分和官能团等进行分析,研究FDN-C对土壤颗粒的作用机理。结果表明:与CA-LS类似,FDN-C也可起到降低压实荷载,提高土体无侧限抗压强度的作用,在掺量超过土样质量的0.7%后,掺加FDN-C试样的压实荷载更低,添加两种减水剂试样的无侧限抗压强度相当;FDN-C和CA-LS均可通过分散土中的“假粉粒”,降低土颗粒表面结合水膜厚度及减少颗粒间距,使土颗粒间更密实,从而提高土体的工程性质;不同的是,CA-LS降低弱结合水膜厚度能力较强,FDN-C降低强结合水膜厚度能力较强。CA-LS分子中较多可交联的游离空位使其具有一定的粘合性,可以使土颗粒更好地胶结到一起,而未发现FDN-C有类似作用。

关键词: FDN-C, CA-LS, 高塑性黏土, 结合水, 无侧限抗压强度, 压实荷载

Abstract: In order to investigate the effect of naphthalene sulfonate water reducer (FDN-C) used in concrete on soil solidification, different amounts of FDN-C were added into high plastic clay, compared with calcium lignosulfonate (CA-LS), the compaction load, unconfined compressive strength (UCS) were tested. The mechanism was analyzed by testing the particle size, microstructure, bonded water, mineral composition and functional group of solidification treated samples. The results show that, like CA-LS, FDN-C can also reduce the compaction load and improve the UCS. When the dosage is higher than 0.7% of soil sample mass, the UCS has little difference, while the compaction load of samples added FDN-C is lower. FDN-C and CA-LS improve the UCS by dispersing soil particles, reducing the thickness of bonded water on the surface of soil particles, and reducing the particle spacing, so that the soil particles can be better filled and compacted with each other, thus improving the engineering properties of soil. CA-LS has a strong ability to reduce the thickness of weak bonded water, while FDN-C reduces the thickness of strong bonded water. More free vacancies in CA-LS molecules make it have certain adhesion, which can make soil particles better cemented together, but the similar effect is not found with FDN-C.

Key words: FDN-C, CA-LS, high plastic clay, bonded water, unconfined compressive strength, compaction load

中图分类号:

TU411

刘云霄, 顾凡, 周辉, 崔桓荣, 习婷. FDN-C对高塑性黏土力学特性的影响与机理分析[J]. 硅酸盐通报, 2023, 42(5): 1822-1830.

LIU Yunxiao, GU Fan, ZHOU Hui, CUI Huanrong, XI Ting. Effect and Mechanism of FDN-C on Mechanical Properties of High Plastic Clay[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(5): 1822-1830.

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