摘要
为了研究复杂环境因素作用下纳米材料对混凝土耐久性及劣化规律的影响,本工作对不同种类(SiO_(2)和TiO_(2))、不同粒径(15 nm和30 nm)及不同掺量(0.2%、0.4%、0.6%、0.8%)(质量分数)的纳米改性混凝土依次进行硫酸盐侵蚀(3 d)和碳化(3 d)劣化处理后进行冻融循环(25次、50次、75次)试验,测定混凝土的质量损失和相对动弹性模量,并采用工业CT(Computer tomography)技术对纳米改性混凝土内部孔隙变化进行研究。结果表明:粒径为15 nm的改性混凝土的耐久性总体上优于粒径为30 nm的改性混凝土;相较于纳米TiO_(2),纳米SiO_(2)改性混凝土的改善效果较好;含量为0.6%的15 nm SiO_(2)混凝土损伤较小,能较好地改善混凝土内部结构。在硫酸盐侵蚀、碳化和冻融循环依次作用下,15 nm-Nano-SiO_(2)、30 nm-Nano-SiO_(2)和30 nm-Nano-TiO_(2)改性混凝土的孔隙率总体呈先降低后增加的趋势;随着冻融次数的增加,不同含量的纳米改性混凝土孔结构演变规律总体一致,不大于0.01 mm^(3)的孔隙体积占比呈降低的趋势,大于10 mm^(3)的孔隙体积占比呈增加的趋势。
In order to study the influence of nano-materials on durability and deterioration of concrete under complex environment,nano-modified concrete with different types(SiO_(2)and TiO_(2)),different particle sizes(15 nm and 30 nm)and different dosage(0.2%,0.4%,0.6%,0.8%)suffered sulfate attack(3 d),carbonation(3 d)and freeze-thaw cycles(25 times,50 times,75 times)in turn.The mass loss and relative dynamic elastic modulus of concrete samples were measured.The pore structure evolution was monitored by industrial CT(computer tomography).The results show that the durability of nano-modified concrete with particle size of 15 nm is better than that with particle size of 30 nm in general.Compared with nano-TiO_(2),the improvement of nano-SiO_(2)modified concrete is better.The damage of 15 nm-SiO_(2)concrete with 0.6%content is less,which can improve the internal structure of concrete better.During the process of sulfate attack,carbonation and freeze-thaw cycles,the porosity of 15 nm-nano-SiO_(2),30 nm-nano-SiO_(2)and 30 nm-nano-TiO_(2)modified concrete generally decreases firstly and then increases.With the increase of freeze-thaw cycles,the pore structure evolution of all nano-particles modified concrete samples have the same regulation.The volume proportion of pores(≤0.01 mm^(3))decreases monotonously,while the volume proportion of pores(>10 mm^(3))increases generally.
作者
刘方
张昆昆
罗滔
马卫卫
蒋伟
LIU Fang;ZHANG Kunkun;LUO Tao;MA Weiwei;JIANG Wei(School of Civil Engineering,Xijing University,Xi’an 710123,China;Shaanxi Key Laboratory of Safety and Durability of Concrete Structures,Xi’an 710123,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2022年第8期112-118,共7页
Materials Reports
基金
国家自然科学基金(51902270)
西京学院特区人才科研启动专项基金(XJ21T01)。
关键词
纳米改性混凝土
复杂环境
冻融损伤
工业CT
孔隙率
nano-modified concrete
complex environment
freeze-thaw damage
industrial CT
porosity
