复合盐浸下多元外掺剂-混凝土抗干湿-冻融循环性能

通过对粉煤灰、硅灰、矿渣、膨胀剂、引气减水剂（Air-Entrained Water Reduce Agent，AEWRA）和水泥基自愈合防水材料（Cementitious Capillary Crystalline Waterproofing Material，CCCWM）等多元外掺剂进行组合搭配掺入混凝土中，设计了5组混凝土配比。分析了复合盐（氯盐、硫酸盐和碳酸盐）浸-干湿-冻融循环等多种因素共同作用下多元外掺剂-混凝土的腐蚀破坏现象、质量损失率、相对动弹性模量衰减规律和抗侵蚀系数变化规律。采用SEM、EDS和XRD，研究了多元外掺剂-混凝土腐蚀的微观结构变化规律。研究结果表明，双掺粉煤灰和硅灰混凝土提高混凝土的抗侵蚀性能作用有限；在双掺粉煤灰和硅灰基础上加入适量的膨胀剂能够较大幅度提高混凝土的抗侵蚀性能，经11次复合盐浸-干湿-冻融循环后，其相对动弹性模量仍然在80%以上，抗侵蚀系数在0.9以上；CCCWM作为一种外掺剂加入混凝土会降低混凝土的耐侵蚀性，经4次复合盐浸-干湿-冻融循环后，相对动弹性模量就降到了60%以下，抗侵蚀系数从1.0降到了0.3。微观机制研究也表明，在复合盐浸-干湿-冻融循环作用下，腐蚀产物钙矾石和方解石共同作用会加速混凝土的腐蚀破坏。

Property of multiple admixture-concrete in multi-salt soaking under wetting-drying and freezing-thawing cycles

Multiple admixtures (e.g. Fly ash, silica fume, slag, expansion agent, air-entrained water reduce agent (AEWRA) and cementitious capillary crystalline waterproofing material (CCCWM)) were added in concrete. Five groups concrete mix was designed, and experiments were conducted to study the damage, mass loss rate, dynamic elastic modulus, erosion-resistance coefficients, with multi-salt soaking and wetting-drying cyclic and freezing-thawing. The microstructure corrosion mechanisms were revealed by SEM, EDS and XRD. The results show that a limitation in improvement of erosion resistance is only for mixing with fly ash and silica fume. Nevertheless, it is significant to improve the erosion resistance of the fly ash and silica fume mixture in which certain amount of expansion agent are added. The dynamic elastic modulus is above 80%, and the erosion-resistance coefficients are above 0.9 after 11 cycles in multi-salt soaking and wetting-drying cyclic and freezing-thawing. CCCWM mixed into concrete can reduce the erosion resistance, the dynamic elastic modulus is below 60%, and the erosion-resistance coefficients are reduced from 1.0 to 0.3 after 4 cycles of multi-salt soaking and wetting-drying cyclic and freezing-thawing. The corrosion products for ettringite and calcium carbonate are found that multi-salt soaking under wetting-drying and freezing-thawing cycles will accelerate corrosion of the concrete, using microscopic mechanism analysis.