粉煤灰对混凝土抗冻及抗硫酸盐性能的影响

发布时间：2018-10-31 20:35

【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。
[Abstract]:[objective] to study the influence mechanism of fly ash on concrete durability under the action of freeze-thaw cycle and sulfate erosion. This paper provides the basis for the application of fly ash in durability concrete engineering. [methods] A single freeze-thaw cycle test was carried out in the solution of 5.0% sodium sulfate by adding 15% fly ash (mass fraction) to 15% of concrete. Single sulfate erosion test and alternate test of freeze-thaw cycle sulfate erosion, The variation law and characteristics of mass loss rate and relative dynamic modulus of concrete are analyzed. [results] the content of fly ash has certain influence on the frost resistance and sulfate corrosion resistance of concrete, and the optimum fly ash content of concrete is 25%. After six cycles of freeze-thaw cycle and sulfate erosion, the mass loss rate and the relative dynamic modulus of the specimen are 0.722 and 80.27 respectively. Compared with concrete specimens with 15% fly ash and 35% fly ash, the mass loss rate is reduced by 0.23% and 0.38%, and the relative dynamic modulus increases by 2.38% and 4.95%, respectively. The results show that fly ash can improve the frost resistance and sulfate corrosion resistance of concrete, and increase with the increase of fly ash content in a certain range. Under the alternate cycle of freeze-thaw failure and sulfate erosion, these two kinds of failure interact and promote each other. [conclusion] addition of 25% fly ash can effectively improve the durability of concrete.
【作者单位】：西安理工大学水利水电学院;
【基金】：国家自然科学基金项目(50779051)
【分类号】：TV431

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