| 摘要: |
| 【目的】研究冻融循环与硫酸盐侵蚀双因素作用下粉煤灰对混凝土耐久性的影响机理，为粉煤灰在耐久性混凝土工程中的应用提供依据。【方法】将粉煤灰掺量（质量分数）为15%，25%，35%的混凝土在质量分数 5.0% 硫酸钠溶液中进行单一冻融循环试验、单一硫酸盐侵蚀试验及冻融循环+硫酸盐侵蚀交替试验，分析混凝土的质量损失率及相对动弹模量的变化规律和特点。【结果】粉煤灰掺量对混凝土抗冻及抗硫酸盐侵蚀具有一定的影响，混凝土的最优粉煤灰掺量为25%。在此掺量下经过6次冻融循环与硫酸盐侵蚀交替试验后，试件的质量损失率为 0.72%，相对动弹模量为80.27%;相比粉煤灰掺量为15%，35%的混凝土试件，其质量损失率分别减少0.23%，0.38%，相对动弹模量分别增加2.38%，4.95%，表明粉煤灰可以提高混凝土的抗冻及抗硫酸盐侵蚀性能，并且在一定范围内随着粉煤灰掺量的增大而提高。冻融破坏与硫酸盐侵蚀交替循环下，这两种破坏相互影响，相互促进。【结论】 掺加25%的粉煤灰可以有效提高混凝土的耐久性。 |
| 关键词: 粉煤灰 混凝土 耐久性 冻融循环 硫酸盐侵蚀 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目（50779051） |
|
| Influence of fly ash on resistance of concrete to freeze and sulfate |
|
LI Yang,WANG Ruijun,YAN Fei，et al
|
| Abstract: |
| 【Objective】This study investigated the influence of fly ash on durability of concrete under freeze-thaw cycle and sulfate attack to provide basis for application of fly ash in durable projects.【Method】In this paper,the damage process of concrete with fly ash contents (mass fraction) of 15%,25%,and 35% under freeze-thaw cycles,sulfate with concentration of 5.0% (mass fraction) Na2SO4,as well as alternate test of freeze thaw cycles and sulfate attack was studied and mass loss and relative dynamic modulus were analyzed.【Result】Content of fly ash had effect on frost and sulfate resistance of concrete face slab,and the optimal amount of fly ash was 25%.After 6 times of freeze thaw cycles and sulfate attack alternate test,the mass loss rate was 0.72% and the relative dynamic elastic modulus was 80.27%,which were decreased by 0.23% and 2.38% compared to the samples with fly ash of 15% and by 0.38% and 4.95% compared to the samples with fly ash of 35%.Fly ash improved the frost and sulfate resistance of concrete,and the improvement increased with the increase of fly ash content in a certain range.Freeze-thaw damage and sulfate attack had mutual influence on concrete.【Conclusion】The fly ash content of 25% effectively improved the durability of concrete. |
| Key words: fly ash concrete durability freeze-thaw cycles sulfate attack |
