【作者】 黄春霞；

【导师】 杜应吉；

【作者基本信息】 西北农林科技大学 ， 结构工程， 2011， 硕士

【摘要】 粉煤灰混凝土是一种被广泛应用的建筑材料。在混凝土中掺入粉煤灰,一方面是可以将粉煤灰有效利用,减小对环境的污染;另一方面可以节约成本,降低工程造价。但有大量研究表明,粉煤灰的性能不稳定,导致粉煤灰对混凝土的耐久性能影响比较大。本文在总结前人研究的基础上,主要通过将理论与试验相结合的方法,研究粉煤灰混凝土的抗碳化性能。工程中经常采用快速碳化试验测定混凝土试块的碳化深度,这种方法能快速得到试验结果。但是快速碳化试验结果和实际工程碳化情况之间的关系研究的不够深入。本文分别对同一配合比的混凝土试块进行快速碳化试验和自然环境碳化对比试验,并从水胶比、粉煤灰掺量、CO₂浓度、环境温、湿度五个方面分析快速碳化试验结果与自然碳化试验结果的关系,经研究主要得出以下结论:1、水胶比是影响混凝土碳化深度的一个重要因素。在两种试验环境中,不同水胶比的混凝土碳化深度发展趋势基本相同:水胶比越大,混凝土碳化深度越大。2、粉煤灰掺量也是影响混凝土耐久性的一个关键因素,其对混凝土碳化深度的影响程度较大,所以当混凝土中掺入粉煤灰时,不能仅用水胶比的大小断定混凝土碳化深度变化规律。3、将不同环境的两种试验结果对比发现,变化的温度和湿度对粉煤灰掺量超过60%的混凝土碳化深度影响比较大。4、当粉煤灰掺量超过60%时,在低CO₂浓度情况下,也很容易碳化。在现有理论模型及快速碳化试验结果的基础上,建立一个适用于大掺量粉煤灰碳化深度的预测模型,并用自然碳化试验数据验证,其计算误差小于15%。更多还原

【Abstract】 At present,the fly ash is a kind of building material that has been applied extensively.When mix the fly ash in the concrete,on the one hand,the fly ash is used effectively and lessen air pollution;on the other hand,reducing and controlling construction cost.But a large number of researches indicate that the property of fly ash is unstable,and it effect to the durability of concrete.This paper based on previous studies,primary research the carbonation resistace of concrete by the theoretical and experimental analyses.In actrual enginerring,normally adopted the quick experiment to determine the carbonation depth,the experimental results is showed fast.But,there is less study on the carbonation of concrete in natural condition and its correlation with artificial accelerated carbonation.The article studies the same mix proportion through the accelerated carbonation experimental and the natural condition carbonation experimental,and it mainly analyzes their relationship from five aspects:water-binder ratio,addition of fly ash,CO₂ concentration,environment temperature,environment humidity,the main contents of the research can be summarized as follows:1.W/B ratio is one of significant factors affecting durability of concrete carbonation depth.Dynamic changes of the carbonation depth of different W/B ration were similarly during these two experimental:the carbonation depth of concrete increases with the water-binder ratio.2.The effect of the fly ash replacement on the carbonation depth is considerable than the water to binder ratio.So we couldn’t judge the concrete carbonation model just by the water-binder ratio when mix the fly ash in concrete.3.According to analyes and compares the two experimental results,we find that when the quantity of fly ash amount to 60 percent,the carbonation depth changes bigger in the changed temperature and humidity environment.4.When the quantity of fly ash amount to 60 percen,the concrete will easily carbonized at low CO₂ concentrations.So we should be cautious to use the concrete with high properties using of large dosage fly ash.On the basis of analyzing the test results,analysis the existing concrete carbonation model,and through this time experimental,reformulate the existed models,get a new prediction model which is suitable to the concrete with high properties using of large dosage fly ash,when it has been proved in this experimental,we find that it has small error .更多还原