自密实混凝土等效砂浆多组分协同增韧试验研究  

Experimental investigation on the synergistic effects in self-compacting concrete equivalent mortar with multi-toughening components

作　　者：葛飞 唐卓 程智清 杨恺 赵洪 龙广成[1] GE Fei;TANG Zhuo;CHENG Zhiqing;YANG Kai;ZHAO Hong;LONG Guangcheng(School of Civil Engineering,Central South University,Changsha 410075,China;Yunnan Traffic Science Research Institute Co.,Ltd.,Kunming 650011,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]云南省交通科学研究院有限公司,云南昆明650011

出　　处：《铁道科学与工程学报》2023年第8期2901-2912,共12页Journal of Railway Science and Engineering

基　　金：云南省交通运输厅科技计划项目(202004AR040022)。

摘　　要：为了改善自密实混凝土(SCC)的断裂韧性,选用橡胶颗粒、可再分散聚合物乳胶粉及聚丙烯纤维3种韧性组分,制备了一系列SCC等效砂浆。通过单边切口梁3点弯曲试验获取了试件的荷载−裂缝口张开位移曲线,对比分析了总掺量一定时,单掺、双掺与三掺上述3种韧性组分对SCC等效砂浆断裂性能的影响,采用协同效应因子定量评价了3种韧性组分的协同增韧效应。此外,通过观察微观形貌和构建物理模型,阐释了不同韧性组分间的协同增韧机理。研究结果表明:单掺聚丙烯纤维对断裂性能的提高幅度最大;任意2组分双掺对断裂性能均发挥正向协同增韧作用;3组分混掺时正向协同增韧作用更显著。乳胶粉有效增强橡胶颗粒和纤维与水泥石基体的界面黏结强度;橡胶颗粒有效缓解裂缝尖端的应力集中,促使纤维和乳胶粉发挥更好的增韧效应;纤维使基体的破坏形式主要为多缝开裂,有利于橡胶颗粒和乳胶粉在基体开裂后持续发挥阻裂作用。3种韧性组分在水泥基体中构建多层次、多尺度的增韧阻裂网络,优势互补协同增韧,从而实现SCC等效砂浆的韧性提升。研究成果可为水泥基材料的增韧减脆提供新思路,为其工程应用提供参考。To improve the fracture toughness of self-compacting concrete(SCC),a series of SCC equivalent mortars incorporating multiple toughening components such as rubber particles,redispersible polymer latex powder,and polypropylene fibers(PP fibers)were produced.The flexural load-crack mouth opening displacement curves were obtained by the three-point bending test of the single-edge notched beams.The effects of single,double and triple addition of the above three toughness components on the fracture properties were analyzed under constant total dosage conditions.The synergistic toughening effect of the three components was quantitatively evaluated using the synergistic effect factor.In addition,the mechanism of synergistic toughness enhancement between different toughening components was illustrated by observing the microstructure of specimens and constructing a physical model of hybrid materials.The results show that,with the addition of polypropylene fibers only,the value of fracture toughness is improved most.The double doping of any two toughness components demonstrates a positive synergistic effect on the fracture properties.Incorporating all three toughening components exhibits the most superior fracture toughness of the study,which means a better synergistic toughening effect of the three materials.Besides,The polymer latex powder can effectively enhance the interfacial adhesive strength between rubber particles fibers and cement matrix;the rubber particles can decentralize the stress concentration at the crack tips,which promotes the PP fibers and polymer latex powder to exert a better toughening effect;PP fibers could transfer crack forms of the matrix into a large number of dense cracks,which is conducive to the continuous anti-cracking effect of rubber particles and latex powder in the softening process.In conclusion,the three toughness components build a multi-level and multi-scale toughening and crack-resistance network in the cement matrix,whose advantages are complementary to each other for better synergi

关 键 词：自密实混凝土 等效砂浆 韧性组分 断裂性能 协同增韧 

分 类 号：TU502[建筑科学—建筑技术科学]