【作者】 王凯；

【导师】 李北星；

【作者基本信息】 武汉理工大学 ， 材料科学与工程， 2017， 硕士

【摘要】 混凝土构件在实际使用过程中因为复杂多变的服役环境,其受到的侵蚀也不是单一的侵蚀因素引起的,而各种侵蚀因素之间相互的影响机理也不甚明了。本文通过设计碳化、冻融与酸雨之间的耦合侵蚀实验,来研究在酸雨-冻融、酸雨-碳化复合作用下混凝土的耐久性化规律,探讨冻融、碳化对混凝土抗酸性能的影响;研究了材料组成对混凝土在酸雨-冻融耦合作用下的耐久性劣化规律的影响及其相关机理,并通过灰色系统理论建立了混凝土在酸雨-冻融耦合作用下关于酸性化深度的寿命预测模型。本文的主要研究内容如下:（1）侵蚀制度对混凝土耐久性劣化的影响。研究了4S、3S-T、T-3S、3S-D、D-3S这五种侵蚀制度下混凝土试件的性能劣化规律,以混凝土质量、抗压强度、动弹性模量、中性化深度、吸水率等为主要的性能劣化指标。研究结果表明,同4S组试件相比,3S-T和T-3S组试件的抗压强度、质量等性能劣化速率更慢,但是中性化深度发展却与4S组相差不大;3S-D和D-3S两组试件在前几个侵蚀周期与4S组相差不大,但是在后几个周期这两组在抗压强度、质量损失和动弹性模量等性能劣化速率远大于4S组;碳化使混凝土受酸雨侵蚀寿命提升了25.4²6.7%,冻融对混凝土中性化过程的影响率为1.5左右;（2）材料组成对混凝土在酸雨-冻融耦合作用下性能劣化的影响。研究了材料组成对混凝土试件在酸雨-冻融（3S-D）复合作用下的耐久性劣化规律,结果表明:与对照组相比,粉煤灰掺量为20%以下时,混凝土试件在3S-D侵蚀制度下的性能劣化速率更慢,粉煤灰掺量为30%时,没有表现出对混凝土试件抗侵蚀能力的提升;掺入矿粉后,混凝土试件的抗侵蚀能力更高,其中矿粉掺量为20%的K20组的抗侵蚀能力最高;含气量为4.5%的混凝土试件在3S-D侵蚀环境下性能更好;经过侵蚀后的腐蚀区的CaO的含量大大减少,Fe₂O₃、Al₂O₃等活性成分的量也有所降低;F20组、K20组侵蚀后的浆体中的活性组分（CaO、Fe₂O₃、Al₂O₃）的总量所占比例要大于纯水泥组,说明K20、F20侵蚀后的浆体受到的侵蚀程度要低,掺入粉煤灰和矿粉后混凝土的抗酸蚀能力得到提升;（3）利用GM（1,1）模型,以酸性化深度为研究对象,建立起在酸雨-冻融耦合作用下的时依性方程;利用GM（1,1）模型计算当保护层厚度为25 mm时的剩余抗压强度系数,不同粉煤灰掺量下混凝土的剩余抗压强度系数在47%⁵2%之间,混凝土抗压强度达到服役寿命的终点。更多还原

【Abstract】 Because of the complex service environment,the erosion of concrete structures in the actual was not caused by a single erosion factors,the mechanism of mutual influence between the various erosion factors are also unclear.In this thesis,the durability of concrete under acid rain and freeze-thaw,acid rain and carbonization was studied,the effects of freezing-thawing and carbonization on the acidity of concrete were discussed thought designing the coupling erosion experiment.The influence of material composition on the durability of concrete under acid rain and freeze thaw and its related mechanism were studied.The life prediction model of concrete under acid rain-freezing thawing interaction was established by gray system theory.The main contents of this paper are as follows:(1)Effect of erosion system on the deterioration of durability of concrete.The performance degradation of concrete specimens under the five erosion systems of 4S,3S-T,T-3S,3S-D and D-3S were studied.Take the change of mass,compressive strength,dynamic modulus,neutral depth,water absorption as the main performance degradation indicators.The results show that the compressive strength and mass of the 3S-T and T-3S specimens are slower than those of the 4S group,but the depth of the neutralization is similar to that of the 4S group.3S-D and D-3S were not significantly different from those in the 4S group,but in the latter several cycles,the rate of deterioration of the strength loss,mass loss and dynamic modulus loss was much higher than that of the 4S group.The service life of concrete under the acid rain corrosion was improved about 25.4% to 26.7%,the effect of freezing-thaw on the erosion of concrete by acid rain is about 1.5;(2)Effect of mineral admixture on performance degradation of concrete under acid rain and freeze-thaw coupling.The effects of mineral admixture on durability of concrete specimen under acid rain-freeze thaw(3S-D)were studied.The results showed that: Compared with the pure cement group,when the content of fly ash is less than 20%,the performance rate of concrete specimen under the 3S-D erosion system is slower,and when the fly ash content is 30%,there is no concrete The anti-erosion ability of the specimen is higher,and the corrosion resistance of the K20 group is the highest when the slag content is 20%;The concrete specimen with gas content of 4.5% has better performance under 3S-D erosion environment.The content of CaO in the corroded area is greatly reduced,the amount of active components such as Al2O3 are also reduced;(CaO,Fe2O3,Al2O3)in the F20 and K20 group were higher than those in the pure cement group,indicating that the erosion rate of the K20 and F20 specimens was lower;The anti-acid corrosion ability of concrete was improved after adding fly ash and slag powder;(3)Using the GM(1,1)model,the acidification depth was used as the object of study to establish the time-dependent equation under the interaction of acid rain and freeze-thaw.The residual compressive strength coefficient when the thickness of the protective layer is 25 mm is calculated by GM(1,1)model,the residual compressive strength under different fly ash content The coefficient is between 47% and 52%,the compressive strength of concrete reaches the end of service life更多还原