摘要
为了更好揭示西部盐渍土地区混凝土耐久性劣化机理及服役寿命,设计了包含腐蚀盐侵蚀、冻融破坏、干湿循环、紫外线照射等多损伤因子在内的室内加速试验,采用动弹性模量评价参数、质量评价参数、抗压强度等宏观评价指标及扫描电子显微镜(SEM)、X射线衍射(XRD)等微观评价指标共同揭示混凝土耐久性损伤劣化机理,提出利用非单调Wiener随机过程建模.结果表明:在多损伤因子耦合作用下混凝土内部凝胶体表面出现裂缝、蜂窝状孔隙,有针状、棒状、薯条状晶体从内部缺陷处生长,腐蚀产物包括钙矾石、石膏等晶体及无胶凝性水镁石,消耗内部凝胶体,产生膨胀应力.干湿循环产生的物理结晶作用及冻融循环产生的胀缩应力加剧了裂缝的形成与发展.可靠性寿命曲线可以很好地描述混凝土在多损伤因子作用下的侵蚀劣化过程,各退化指标中通过质量得到的可靠性寿命时间最长,动弹性模量次之,强度退化指标可靠性寿命最短.以3类退化指标在0.35可靠度下的平均时间作为混凝土在多损伤因子作用下的可靠性寿命,可得C45,C40及C35混凝土的室内加速寿命分别为182.3,138.3和104.6 d.
In order to reveal the durability deterioration mechanism and service life of concrete in the western saline soil area better,an accelerated indoor test including damage factors such as corrosion salt erosion,freeze-thaw damage,dry-wet cycle and ultraviolet radiation was designed.Macroscopic evaluation indexes such as dynamic elastic modulus evaluation parameters,quality evaluation parameters and compressive strength as well as microscopic evaluation indexes such as SEM and XRD were used to reveal jointly the deterioration mechanism of concrete durability.A nonmonotone Wiener stochastic process was proposed for modeling.The results show that:Under the coupling action of multiple damage factors,cracks and honeycomb-like pores appear on the surface of concrete internal gel,and spicules,and there are needle-like,rod-like,and chip-like crystals growing from the internal defects.Corrosion products include crystals such as ettringite,gypsum,and non-gelling brucite which consume the internal gel and produce expansion stress.The physical crystallization produced by the dry-wet cycles and the expansion-contraction stress produced by the freeze-thaw cycles intensify the formation and development of cracks.The reliability life curve can well describe the erosion degradation process of concrete under the action of multiple damage factors of saline soil.Among the degradation indexes,the reliability life obtained by quality is the longest,the dynamic elastic modulus is the second,and the reliability degradation life of the strength degradation index is the shortest.The average time of three degradation indexes at 0.35 degree of reliability is taken as the reliability life of concrete under multi damage factors,the indoor accelerated life of C45,C40 and C35 concrete is 182.3,138.3 and 104.6 days respectively.
作者
路承功
乔宏霞
魏智强
李刊
付勇
LU Chenggong;QIAO Hongxia;WEI Zhiqiang;LI Kan;FU Yong(School of Civil Engineering,Lanzhou University of Technology,Lanzhou,Gansu 730050,China;Western Center of Disaster Mitigation in Civil Engineering of Ministry of Education.Lanzhou University of Technology,Lanzhou,Gansu 730050,China;School of Science,Lanzhou University of Technology,Lanzhou,Gansu 730050,China)
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2021年第2期265-272,288,共9页
Journal of China University of Mining & Technology
基金
国家自然科学基金项目(51168031,51868044)。
