服役混凝土的抗冻性研究-结构工程专业论文.docxVIP

摘要 摘要 万方数据 万方数据 摘 要 长期以来，研究混凝土的抗冻性能大多是以“纯材料”形式进行的，并未 考虑荷载的影响。混凝土在实际结构中是要承受荷载（自重加有效荷载）的， 荷载作用下混凝土孔结构发生变化，在“纯材料”形式下测试混凝土的抗冻性 能得到的结果往往与实际情况不相符。目前，考虑荷载作用的研究多是以带“夹 具”的形式进行的，实际操作比较复杂，较难得到精确的结果。本文采用“先 加载，后测试”的方法研究应力水平、强度以及单掺粉煤灰、复掺粉煤灰-硅灰 对服役混凝土抗冻性的影响规律。 研究结果表明：1）服役混凝土（40%～60%应力水平）的抗冻性与“纯材料” （0%应力水平）混凝土相比存在较大差异，服役混凝土的质量损失率、动弹模 损失约为“纯材料”混凝土的 1.5 倍；2）中低强度服役混凝土与高强服役混凝 土的抗冻性能相差不大；3）单掺粉煤灰服役混凝土的质量损失率约为普通服役 混凝土（未掺矿物掺合料）的 95%；复掺粉煤灰-硅灰服役混凝土的质量损失率 约为普通服役混凝土的 90%；单掺粉煤灰、复掺粉煤灰-硅灰服役混凝土的动弹 模损失约为普通服役混凝土的 90%。矿物掺合料提高服役混凝土的抗冻性能效 果不明显。 关键词：服役混凝土；应力水平；抗冻性能； Ⅰ Abst Abstract ABSTRACT For a long period, researches on freeze-thaw resistance of concrete are mostly based on pure material form ,without considering the impact of load. Concrete in structure is to withstand load (weight plus payload) which leads the internal pore structure of concrete changes. The results of testing freeze-thaw resistance of con- crete in a pure material form were often not consistent with actual situation. Cur- rent studies considering loads are often in the form of multi-band clamp, whose operation is complex, difficult to get accurate results. This thesis used the testing after loading method to study rules of stress levels, intensity and fly ash, fly ash complex - silica fume on freeze-thaw resistance of concrete in service. Research draw the following conclusions : There is a difference between service concrete(40%～60% stress level) and “pure material”(0% stress level) concrete on freeze-thaw resistance of concrete. the mass loss rate and the dynamic modulus loss of pure material concrete is about 1.5 times the service concrete’s. Low-intensity concrete in service and high-strength concrete in service has nearly the same freeze-thaw resistance. Mass loss rate of fly ash concrete in service is about 95% of normal concrete (without admixture) in service. Mass loss rate of fly ash complex-si lica fume concrete in service is about 90% of normal concrete in service. Dy namic modulus loss of fly ash, fly ash