Effect of sulfate attack on geopolymer mortars at early ages of exposure

IF 3.4 3区工程技术 Q2 CONSTRUCTION & BUILDING TECHNOLOGY Materials and Structures Pub Date : 2024-11-21 DOI:10.1617/s11527-024-02526-4

Neusa Aparecida Munhak Beltrame, Amanda Venancio Trisotto, Rafaela Souto, João Claudio Nascimento da Silva, Bárbara Cicuto Gonçalves Pereira, Ronaldo A. Medeiros-Junior

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Abstract

Geopolymers have generated interest due to their potential to be used as an alternative binder to Portland cement. This study investigated the effects of sodium and magnesium sulfate attack on metakaolin-based geopolymer mortars (MK) considering different concentrations of silica in the activator (Ms), Na₂O/MK ratio, and the inclusion of an air-entraining additive. Geopolymer mortars prepared with metakaolin and a combination of Na₂SiO₃ and NaOH were cured for 84 days. The visual appearance, linear dimensional change, mass variation, and microstructure were monitored during two weeks of immersion in a Na₂SO₄ and MgSO₄ solution at 40 ºC to understand the behavior of this material in early ages. The results indicated that the highest compressive strength was achieved with Ms = 1.5 and Na₂O/MK content of 22%. The addition of the air-entrainer to the geopolymeric mixtures minimized the expansion of the samples. This effect was attributed to the accommodation of the expansive phases in the air bubbles. The sulfate resistance of the geopolymeric material is significantly dependent on the dosage and different performances were found in the first weeks of exposure to sulfates.

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硫酸盐侵蚀对土工聚合物砂浆早期龄期的影响

土工聚合物具有替代波特兰水泥粘结剂的潜力，因此引起了人们的兴趣。本研究调查了硫酸钠和硫酸镁对偏高岭土基土工聚合物砂浆（MK）的侵蚀作用，考虑了活化剂（Ms）中不同浓度的二氧化硅、Na2O/MK 比率以及是否加入引气添加剂。使用偏高岭土以及 Na2SiO3 和 NaOH 组合制备的土工聚合物砂浆固化了 84 天。在 40 ºC 的 Na2SO4 和 MgSO4 溶液中浸泡两周后，对其外观、线性尺寸变化、质量变化和微观结构进行了监测，以了解这种材料在早期龄期的行为。结果表明，当 Ms = 1.5 和 Na2O/MK 含量为 22% 时，抗压强度最高。在土工聚合物混合物中加入引气剂后，样品的膨胀率降到了最低。这种效果归因于气泡对膨胀相的容纳。土工聚合物材料的抗硫酸盐性能与用量有很大关系，在暴露于硫酸盐的最初几周内就会出现不同的表现。

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来源期刊

Materials and Structures 工程技术-材料科学：综合

CiteScore

6.40

自引率

7.90%

发文量

222

审稿时长

5.9 months

期刊介绍： Materials and Structures, the flagship publication of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM), provides a unique international and interdisciplinary forum for new research findings on the performance of construction materials. A leader in cutting-edge research, the journal is dedicated to the publication of high quality papers examining the fundamental properties of building materials, their characterization and processing techniques, modeling, standardization of test methods, and the application of research results in building and civil engineering. Materials and Structures also publishes comprehensive reports prepared by the RILEM’s technical committees.