摘要
我国水泥行业每年排放大量二氧化碳,为降低水泥用量,采用纳米二氧化钛及秸秆灰替代部分水泥,研究不同混合料掺量对混凝土坍落度、抗压及抗拉强度等影响,同时利用SEM探究双掺混合料对混凝土微观结构的影响,并使用CT扫描仪研究单轴压缩下混凝土损伤规律,且利用MATLAB软件提取裂缝长度。试验结果表明,随混合料掺量增加,坍落度呈先增加后下降趋势;掺入纳米二氧化钛与秸秆灰对混凝土早期抗压及抗拉强度提高影响较小,对后期强度影响较大,掺入10%纳米二氧化钛与15%秸秆灰时混凝土抗压及抗拉强度达到最高;SEM图像显示,纳米二氧化钛及秸秆灰协同作用可有效降低孔隙率改善混凝土微观结构;随应变增加,不同掺量下CT数均值呈先增加后下降趋势;掺入纳米二氧化钛及秸秆灰时,裂缝总长度呈下降趋势,但当掺入20%的秸秆灰时,裂缝总长度达172.6μm,过量秸秆灰对混凝土微观结构产生不利影响。
China′s cement industry emits a large amount of carbon dioxide every year,in order to reduce the amount of cement,it uses nano-TiO2 and straw ash to replace part of the cement,to study the effect of different mixes on concrete slump,compressive strength,etc,using SEM to explore the effect of double mixes on the microstructure of concrete,and use CT scanner to study the damage law of concrete under uniaxial compression.Extraction of fracture length by MATLAB software.The test results show that the slump tends to increase and then decrease with the increase of the mixture.The effect of incorporating nano-TiO2 and straw ash on the early compressive and tensile strength of concrete is relatively small,but the effect on the later strength is greater,with the highest compressive and tensile strength of concrete being achieved when 10%nano-TiO2 and 15%straw ash are incorporated.SEM images show that the synergistic effect of nano-TiO2 and straw ash can effectively reduce the porosity and improve the microstructure of concrete.With the increase of strain,the mean value of CT number increases and then decreases at different dosing levels.The total length of cracks decreases when nano-TiO2 and straw ash are incorporated,but when 20%of straw ash is incorporated,the total length of cracks reaches 172.6μm,and the excessive amount of straw ash has a negative effect on the microstructure of concrete.
作者
刘先南
王珂
李学军
LIU Xiannan;WANG Ke;LI Xuejun(Guangzhou Baiyun International Airport Co.,Ltd.,Guangzhou 510470,China;Guangdong Yuewan Concrete Co.,Ltd.,Zhongshan 528400,China;South China University of Technology,Guangzhou 510641,China)
出处
《混凝土》
CAS
北大核心
2023年第6期125-129,133,共6页
Concrete
基金
国家自然科学青年基金(517083106)
广东省自然科学基金项目(2019A030314799)。
