In order to investigate the development law of carbonization depth of manufactured sand concrete under the influence of internal and external multiple factors,rapid carbonization tests were used to study the carbonization rate of manufactured sand concrete at different carbonization ages under the influence of cement and mineral admixtures dosage,water to binder ratio and additive dosage,stone powder content,fineness modulus,curing time,and CO2 concentration,and combined with the scanning electron microscope for the microstructural analysis.The results showed that the replacement amount of fly ash increased from 0 to 40％,and the carbonation depth of concrete increased by 90％after 28 days of rapid carbonation.When the water to binder ratio is greater than 0.45,the carbonization depth still maintains a significant increase after 14 days of rapid carbonization.The content of machine-made sand powder increases,and the carbonation depth of concrete shows a trend of first decreasing and then increasing,stone powder content in 10％,the carbonation depth at 28 days is the minimum.The fineness modulus increases,and the carbonization depth at all age increases accordingly.The curing time is particularly important for the improvement of carbonation resistance of manufactured sand concrete.Concrete carbonation rate in the early stage is greatly affected by CO2 concentration,when the CO2 concentration exceeds 20％,there is no significant difference in the later carbonation rate.The carbonation depth of concrete decreases with the increase of compressive strength,and there is a good correlation between the two.The microstructure observation confirms that the appropriate content of stone powder has an improvement effect on the performance of manufactured sand concrete before and after carbonization.Finally,based on the experimental results,a multivariate nonlinear analysis was conducted to establish a prediction model for the carbonation depth of manufactured sand concrete considering multiple internal and external factors,which can provide reference for the durability prediction of manufactured sand concrete.
关键词
机制砂混凝土/碳化深度/石粉含量/微观结构/预测模型
Key words
manufactured sand concrete/carbonization depth/stone powder content/microstructure/prediction model
维普
万方数据