含粗骨料超高性能混凝土与钢筋黏结性能研究  

Study on Bonding Performance of Ultra-high Performance Concrete with Coarse Aggregate and Reinforcement Bars

作　　者：黄远[1,2] 吴仁迪 HUANG Yuan;WU Rendi(College of Civil Engineering,Hunan University,Changsha 410082,China;Key Laboratory for Damage Diagnosis of Engineering Structures of Hunan Province(Hunan University),Changsha 410082,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]工程结构损伤诊断湖南省重点实验室(湖南大学),湖南长沙410082

出　　处：《湖南大学学报(自然科学版)》2025年第3期170-179,共10页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(51890901);湖南省自然科学基金资助项目(2020JJ2003,2020RC5005)。

摘　　要：在超高性能混凝土(UHPC)中加入粗骨料可以有效地解决UHPC自身收缩大、成本高等问题.为了研究弯曲应力状态下含粗骨料超高性能混凝土(UHPC-CA)与钢筋的黏结性能,对12根UHPC-CA搭接梁式试件进行4点弯曲加载试验,并采用钢筋开槽粘贴应变片的方式测量了沿搭接钢筋长度方向黏结应力,研究其分布规律.主要研究参数包括粗骨料粒径、粗骨料含量、搭接长度以及保护层厚度.试验结果表明,试件破坏以劈裂破坏为主.粗骨料对钢筋的黏结性能具有双重影响,一方面,骨料与钢筋的互锁机制能增强机械咬合力,提升黏结强度;另一方面,骨料的加入会增加材料的不均匀程度,对黏结性能产生不利影响.5~10 mm粒径的骨料对黏结性能的影响比10~15 mm粒径的骨料更显著,当骨料含量达到800 kg/m^(3)时,钢筋黏结应力沿搭接长度方向的分布变得更均匀.增大钢筋搭接长度和增加混凝土保护层厚度均能增强对黏结强度的保持作用,从而提高试件的峰后黏结强度.提出了考虑粗骨料特征参数的UHPC-CA劈裂黏结强度计算表达式,计算结果与试验结果吻合良好.The inclusion of coarse aggregates in ultra-high performance concrete(UHPC)can effectively address the issues of high shrinkage and high cost associated with UHPC.This study investigated the bond properties of UHPC with coarse aggregate(UHPC-CA)and steel reinforcement under flexural stress using 12 lap-spliced beam specimens in 4-point bending tests.The distribution pattern of bond stress along the length of the lap splice reinforcement has been obtained by milling a slot on the surface of the steel reinforcement and pasting strain gauges evenly.Key variables studied included coarse aggregate(CA)size,CA content,splice length,and cover depth.The specimens primarily failed in splitting.The results showed that CA affected the bond performance in two ways:it enhanced the mechanical interlock and bonding strength but also increased material inhomogeneity,which may reduce bond quality.Notably,smaller CA(5~10 mm)had a more significant impact than larger CA(10~15 mm).Increasing CA content to 800 kg/m^(3) made the bond stress distribution along the splice length more uniform.Extending splice length and increasing cover depth improved bonding strength retention and post-peak performance.A formula was developed to predict splitting bond strength,aligning well with experimental findings.

关 键 词：超高性能混凝土 粗骨料 黏结性能 梁式试验 搭接 

分 类 号：TU375.1[建筑科学—结构工程]