Alkali-activated calcined clay blended cement: Effect of NaOH activator on performance of HPEG PCEs and on early strength

IF 10.9 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Cement and Concrete Research Pub Date : 2024-06-20 DOI:10.1016/j.cemconres.2024.107588

Jiaxin Chen, Johann Plank

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Abstract

The effect of NaOH on dispersing performance of HPEG PCE superplasticizers and early strength was studied in a calcined clay (CC) blended cement (OPC:CC = 70:30 wt./wt.). Activator impact on workability and mechanical properties was investigated on mortar via fluidity and strength tests. The results revealed a time-dependent impact. At early ages (16 h – 3 d), the strength of the NaOH-activated OPC/CC blend exceeds that of OPC, while at longer curing times ( $>$ 3 d) it is $\sim$ 30 % below that of OPC. Among the HPEG PCEs tested, the polymer possessing a medium long side chain (n_EO = 50) performed best. Generally, NaOH addition prompted significantly increased PCE dosages. Heat flow calorimetry and in-situ XRD measurements suggest that NaOH promotes initial hydration of both OPC and CC, but later delays OPC reaction. Zeta potential measurements confirmed that NaOH significantly reduces the adsorbed amount of PCE on the binder, thus explaining higher dosage requirement.

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碱活化煅烧粘土混合水泥：NaOH 活化剂对 HPEG PCE 性能和早期强度的影响

在煅烧粘土（CC）混合水泥（OPC:CC = 70:30 wt./wt.）中研究了 NaOH 对 HPEG PCE 增塑剂分散性能和早期强度的影响。通过流动性和强度测试研究了活化剂对砂浆工作性和机械性能的影响。结果显示其影响与时间有关。在早期龄期（16 h - 3 d），NaOH 活化的 OPC/CC 混合物的强度超过了 OPC，而在较长的固化时间（3 d），其强度比 OPC 低 30%。在测试的 HPEG PCE 中，具有中等长侧链（nEO = 50）的聚合物性能最好。一般来说，加入 NaOH 会显著增加 PCE 的用量。热流量热法和原位 XRD 测量表明，NaOH 可促进 OPC 和 CC 的初步水合，但随后会延迟 OPC 的反应。Zeta 电位测量证实，NaOH 能显著减少粘合剂上的 PCE 吸附量，从而解释了为何需要增加用量。

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来源期刊

Cement and Concrete Research 工程技术-材料科学：综合

CiteScore

20.90

自引率

12.30%

发文量

318

审稿时长

53 days

期刊介绍： Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.