西北盐渍干寒地区聚丙烯纤维混凝土耐久性损伤试验研究  

Experimental Investigation on Durability Damage of Polypropylene Fiber Reinforced Concrete in Saline and Dry Cold Region of Northwest China

作　　者：张秉宗 贡力[1,2] 杜强业 梁颖 宫雪磊 杜秀萍[3] ZHANG Bingzong;GONG Li;DU Qiangye;LIANG Ying;GONG Xuelei;DU Xiuping(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Institute of Water Diversion Engineering and Water Security,Lanzhou Jiaotong University,Lanzhou 730070,China;Baoding Survey and Design Institute of Water Conservancy and Hydro Power,Baoding 071000,Hebei,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070 [2]兰州交通大学调水工程及输水安全研究所,兰州730070 [3]保定市水利水电勘测设计院,河北保定071000

出　　处：《材料导报》2022年第17期104-110,共7页Materials Reports

基　　金：国家自然科学基金(51969011);甘肃省科技计划资助(20JR10RA274;20JR2RA002;21JR7RA301);甘肃省教育厅:优秀研究生“创新之星”项目(2021CXZX-640)。

摘　　要：西北盐渍干寒地区的盐胀、溶陷和腐蚀等工程病害严重影响混凝土正常使用。针对水工混凝土耐久性突出问题,以引大入秦工程为例,在现场取样基础上对混凝土残渣进行XRD分析确定侵蚀产物;结合混凝土侵蚀机理,设计室内劣化加速试验,利用核磁共振技术,从细观角度分析混凝土内部孔隙发展状况;选取混凝土相对动弹性模量、抗压强度损失率、质量损失率等宏观指标,结合SEM微观图像,探究聚丙烯纤维混凝土(PFRC)的耐久性损伤过程规律及特征。研究表明:聚丙烯纤维能够增加混凝土在复盐溶液中的循环次数,有效减少脱落,试验停止时,掺量为0.9 kg/m^(3)的PFRC比普通混凝土质量损失减小3.61%;从细观层面看,聚丙烯纤维对浇筑完成后的混凝土微观孔隙结构稍有改善,但不明显;在混凝土“加速劣化”阶段,聚丙烯纤维能有效抑制混凝土中毛细孔和非毛细孔的增多;从微观形貌看,混凝土内部孔隙处生成的腐蚀产物是裂缝发展的主因,聚丙烯纤维不能阻止钙矾石、石膏等腐蚀产物生成。The normal use of concrete is severely affected by engineering diseases such as salt swelling,melt sinking and corrosion in a certain environment of saltness-dryness-coldness in the northwest of China.Datong River-Qingwangchuan Water Diversion Project was selected as a research scope in order to study the outstanding problems of concrete durability.On the basis of collecting concrete residue samples within the research scope,the concrete residue was analyzed by XRD to determine the corrosion product.At the same time,an indoor deterioration accelerated test was designed based on the corrosion mechanism of concrete to analyze the propagation of internal pores in concrete from a meso-level perspective by using nuclear magnetic resonance technology.Combining with SEM observations,durability indicators such as relative dynamic elastic modulus,compressive properties and the mass loss rate were selected to explore the law and characteristics of the durability damage process of polypropylene fiber reinforced concrete(PFRC).The results show that polypropylene fiber can increase the number of cycles of concrete in the compound salt solution and effectively reduce shedding.When the test is stopped,the mass loss of PFRC with a dosage of 0.9 kg/m^(3)is reduced by 3.61%compared with that of ordinary concrete.From the meso-level,polypropylene fiber slightly improves the microscopic pore structure of concrete after pouring.In the‘accelerated deterioration’stage of concrete,polypropylene fiber can effectively inhibit the increase of pores and non-capillary pores in concrete.From the micro-level,the corrosion products generated in the internal pores of concrete are the main reason of the propagation of cracks;polypropylene fiber cannot prevent the formation of corrosion products such as ettringite and gypsum.

关 键 词：聚丙烯纤维混凝土 盐渍土环境 冻融循环 耦合加速试验 耐久性损伤 微观结构 

分 类 号：TU528[建筑科学—建筑技术科学]