Effect of silica fume and slump-retaining polycarboxylate-based dispersant on the development of properties of portland cement paste
Effect of silica fume and slump-retaining polycarboxylate-based dispersant on the development of properties of portland cement paste
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DOI：
10.1016/j.cemconcomp.2019.03.021
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发表时间：
2019-05-01
影响因子：
10.5
通讯作者：
Khayat, Kamal Henri
中科院分区：
文献类型：
--
作者：
Meng, Weina;Kumar, Aditya;Khayat, Kamal Henri
研究了聚羧酸醚保坍分散剂硅灰（SF）及其复配对普通波特兰水泥浆体新拌和硬化性能的影响。所研究的性质包括水合动力学、流变性质（即，塑性粘度和屈服应力）、凝固时间和抗压强度。在质量替代水平为0%、10%、20%和30%时，用SF部分替代水泥。PCE剂量包括粘合剂的0质量%、0.6质量%、1.2质量%、1.8质量%和2.4质量%。结果表明，SF加快水泥水化速率，并减少与其在浆体中的含量有关的初/终凝时间。这是由于在SF表面上提供了额外的C-S-H成核位点。然而，当PCE存在时，由SF引起的这种增强被抑制。除了提高水泥水化速率，SF减少颗粒间的间距，从而放大流变性能。相比之下，PCE降低粘度和屈服应力。SF和PCE均降低1天抗压强度，这是由于水泥稀释（由SF引起）和水泥早期水化动力学抑制（由PCE引起）的影响。然而，7天的抗压强度，是大致相同的二元膏体之间，这是因为SF和PCE的加速和减速效果，分别是不太明显，在以后的年龄。最后，建立了水化动力学、流变性能和抗压强度演变之间的稳健相关性。这些相关性可为高/超高性能混凝土的胶凝材料配方和配合比优化提供依据。
This paper investigates the effect of silica fume (SF), a slump-retaining polycarboxylate ether (PCE) dispersant, and their combinations, on the fresh and hardened properties of ordinary portland cement paste. The investigated properties include hydration kinetics, rheological properties (i.e., plastic viscosity and yield stress), setting time, and compressive strength. Cement was partially replaced by SF at mass substitution levels of 0%, 10%, 20%, and 30%. The PCE dosages included 0%, 0.6%, 1.2%, 1.8%, and 2.4%, by mass of the binder. The results indicate that SF accelerates cement hydration rates and reduces the time of initial/final setting in relation to its content in the paste. This is due to the provision of additional C-S-H nucleation sites on SF surfaces. However, when PCE is present, such enhancement induced by SF is suppressed. In addition to enhancing cement hydration rate, SF reduces inter-particle spacing, thus amplifying rheological properties. In contrast, PCE reduces viscosity and yield stress. Both SF and PCE reduce 1-day compressive strength due to the effects of cement dilution (caused by SF) and the suppression of early-age hydration kinetics of cement (caused by PCE). The 7-day compressive strength, however, are broadly the same among the binary pastes; this is because the acceleratory and retarding effects of SF and PCE, respectively, are less pronounced at later ages. Finally, robust correlations between hydration kinetics, rheological properties, and compressive strength evolution are established. Those correlations can provide a basis for optimizing binder formulation and proportioning of high/ultra-high performance concrete.