RESEARCH ON THE DAMAGE OF GEOPOLYMER CONCRETE UNDER THE ACTION OF SALTWATER AND FREEZE-THAW
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摘要: 采用钠水玻璃(Na2O·mSiO2)激发高活性偏高岭土和粉煤灰的混合物制备地聚物混凝土,研究地聚物混凝土在盐溶液中(3.5% NaCl溶液、3.5% Na2SO4溶液、3.5% Na2SO4溶液+3.5% NaCl溶液和纯水)经过冻融循环后的损伤程度,分析各冻融循环周期下试件的表观形貌变化、质量损失率变化和相对动弹性模量变化规律。结果表明:盐侵蚀作用下,随着冻融次数的增加,试件表面浆体的剥落现象越来越明显,质量和相对动弹性模量损失严重。由质量损失率和相对动弹性模量变化曲线可知,在四种溶液中相同冻融次数下,地聚物混凝土的冻融破坏程度由强到弱依次为复合盐冻、氯盐冻、水冻、硫酸盐冻,说明复盐环境对地聚物混凝土的抗冻性能最不利。研究成果可为盐水与冻融环境中的地聚物混凝土结构工程设计提供一些理论参考。Abstract: Geopolymer concrete was prepared with a mixture of high-activity metakaolin excited by fly ash with sodium waterglass (Na2O·mSiO2). The damage degree of geopolymer concrete immersed in the saline solution (3.5% NaCl solution, 3.5% Na2SO4 solution, 3.5% Na2SO4 +3.5% NaCl solution and tap water) after being subjected to freeze-thaw cycles was studied. The changes in the apparent morphology, mass loss rate and relative dynamic elastic modulus of the specimens in each freezing-thawing cycle were analyzed. The results showed that, under the action of salt erosion, with the increase of freezing-thawing times, the phenomenon of slurry spalling on the surface of specimen became more and more obvious, and the loss of mass and relative dynamic elastic modulus was more serious. According to the curve of mass loss rate and relative dynamic modulus of elasticity, it could be seen that the freeze-thaw damage of geopolymer concrete under the same freeze-thaw times in the four kinds of solutions from strong to weak was as follows:compound salt freeze, chloride freeze, water freeze and sulfate freeze. It was indicated that the composite salt environment was the most unfavorable to the frost resistance of geopolymer concrete. The research results can provide some theoretical references for the design of geopolymer concrete structures in saltwater and freeze-thaw environment.
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Key words:
- geopolymer concrete /
- salt erosion /
- freeze-thaw cycle /
- damage test /
- evolution equation
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