Dispersant mechanisms in clays stabilized with MgO-based cement

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement and Concrete Research Pub Date : 2025-09-19 DOI:10.1016/j.cemconres.2025.108040

Raphael Kuhn , Pietro Lura , Daniel Rentsch , Guillaume Habert , Ellina Bernard

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引用次数: 0

Abstract

Clay-based, low-CO₂ cement-stabilized materials offer a sustainable alternative to conventional building materials. This study examines the impact of various admixtures (Na-hexametaphosphate, Na‑carbonate, Na-silicate, Na-citrate, and Na-oxalate) on the rheological behavior of poured systems containing a MgO-metakaolin cement as stabilizer. The yield stress reduction follows the order Na-hexametaphosphate > Na-silicate > Na-citrate > Na-oxalate ≥ Na‑carbonate > no admixture. The zeta potential data with the solution analysis of the suspensions show that the adsorption of admixtures and/or a change in pH leads to a more negative surface, enhancing dispersion through electrostatic repulsion. Silicate and phosphate are not found in the suspension, ²⁹Si ssNMR indicates that silicate precipitates and polymerizes most likely as M-S-H. The phosphates are most likely adsorbed onto particles with opening of the phosphate rings observed by ³¹P NMR. The anionic charge density of adsorbed polyphosphates was calculated and linked to the decreased colloid sizes observed with increasing Na-hexametaphosphate concentration.

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mgo基水泥稳定粘土中的分散剂机制

粘土基、低二氧化碳水泥稳定材料提供了传统建筑材料的可持续替代品。本研究考察了各种外加剂（六偏磷酸钠、碳酸钠、硅酸钠、柠檬酸钠和草酸钠）对含有氧化镁偏高岭土水泥作为稳定剂的浇注体系流变行为的影响。屈服应力降低的顺序为：Na-六偏磷酸钠>； Na-硅酸钠>； Na-柠檬酸钠>； Na-草酸钠≥Na-碳酸盐>；无外加剂。zeta电位数据与悬浮液的溶液分析表明，外加剂的吸附和/或pH的变化导致表面更负，通过静电排斥增强分散。悬浮液中没有发现硅酸盐和磷酸盐，29Si ssNMR表明硅酸盐沉淀和聚合最有可能形成M-S-H。经核磁共振31P观察，磷酸盐极有可能吸附在磷酸环开口的颗粒上。计算了吸附的聚磷酸盐的阴离子电荷密度，并将其与随着na -六偏磷酸钠浓度的增加而观察到的胶体尺寸的减小联系起来。

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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.