Effect of hydroxypropyl-methyl cellulose ether on rheology of cement paste plasticized by polycarboxylate superplasticizer
Effect of hydroxypropyl-methyl cellulose ether on rheology of cement paste plasticized by polycarboxylate superplasticizer
复制标题
羟丙基甲基纤维素醚对聚羧酸高效减水剂塑化水泥净浆流变性能的影响
DOI：
10.1016/j.conbuildmat.2017.11.010
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发表时间：
2018-01-30
影响因子：
7.4
通讯作者：
He, Xingyang
中科院分区：
文献类型：
--
作者：
Ma, Baoguo;Peng, Yi;He, Xingyang
通常，在实际混凝土中掺入羟丙基甲基纤维素醚(HPMC)可以解决渗漏和离析问题。然而，这对聚羧酸盐高效减水剂(PCE)的分散总是有负面影响的。为了深入了解这一负面影响，研究了PCE和HPMC对水泥净浆流变性的影响，并用总有机碳分析仪、X射线光电子能谱和动态光散射等手段揭示了PCE和HPMC相互作用的机理。结果表明，HPMC的掺入能显著提高PCE增塑水泥净浆的塑性粘度和屈服应力，对流动性有负面影响。造成这种负面影响的一个原因是，HPMC可以与孔溶液中的钙离子结合，形成团聚甚至沉淀，从而消耗PCE并使其失效；另一个原因是HPMC可以通过竞争吸附扰乱PCE的吸附，从而发挥分散作用。相反，HPMC的相对分子质量越大，其负面影响越大。实验结果表明，适当的HPMC相对分子质量可以平衡HPMC对PCE分散的负面影响和HPMC的增粘作用。这些结果有望为在实际工程中使用HPMC来优化PCE增塑的水泥基材料的工作性提供指导。(C)2017爱思唯尔有限公司。保留所有权利。
Generally, bleeding and segregation can be solved with addition of hydroxypropyl-methyl cellulose ether (HPMC) in real concrete. However, the negative effect of this on dispersion of polycarboxylate superplasticizer (PCE) can always be found. In order to deeply understand this negative effect, the rheology of cement paste in the presence of PCE and HPMC was investigated, and the mechanism behind the interaction between PCE and HPMC was revealed with total organic carbon analyzer, X-ray photoelectron spectrometer and dynamic light scattering. The results show that addition of HPMC can obviously increase the plastic viscosity and yield stress of cement paste plasticized by PCE, showing negative effect on fluidity. One reason for this negative effect is that HPMC can be combined with Ca2+ in pore solution, resulting in agglomeration and even precipitation, which can consume and invalid PCE; another reason is that HPMC can perturb the adsorption of PCE to exert dispersion by competitive adsorption. By contrast, much stronger negative effect can be observed with greater molecular weight of HPMC. It is inferred that proper molecular weight of HPMC can balance the negative effect of HPMC on dispersion of PCE and the viscosity-enhancing effect of HPMC to improve bleeding and segregation. Such results were expected to provide guidance on the use of HPMC to optimize workability of cement-based materials plasticized by PCE in real engineering practice. (C) 2017 Elsevier Ltd. All rights reserved.