苏捷 秦红杰 史才军 方志

摘要：通過5组再生骨料取代率和4组钢纤维体积掺量小梁试件的四点弯曲试验，研究了再生骨料取代率和钢纤维掺量对再生混凝土抗折强度及尺寸效应的影响.结果表明：各规格小梁试件的抗折强度均存在尺寸效应，随再生骨料取代率的增加，再生混凝土抗折强度尺寸效应呈先增大后降低的规律，取代率为75%小梁试件抗折强度尺寸效应约分别为取代率为0和100%试件的1.32倍和1.09倍.钢纤维掺量对再生混凝土抗折强度尺寸效应有一定影响，当掺量为0～0.75%时，钢纤维掺量越大，尺寸效应越明显，钢纤维掺量分别为0、0.25%和0.50%时，试件抗折强度尺寸效应约分别为钢纤维掺量0.75%试件的77%、85%和94%.钢纤维掺量较大时，钢纤维掺量对尺寸效应的影响较弱，钢纤维掺量为0.75%试件抗折强度尺寸效应度约为1.00%掺量试件的99%.提出了再生混凝土抗折强度尺寸效应律计算公式，可用于再生混凝土抗折强度的分析计算.

关键词：再生骨料混凝土；抗折强度；尺寸效应；钢纤维；取代率

中图分类号：TU528文献标志码：A

基金项目：国家自然科学基金资助项目（51408213），National Natural Science Foundation of China（51408213）；湖南省自然科学基金资助项目（2018JJ2042），Natural Science Foundation of Hunan Province of China（2018JJ2042）

Experimental Study on Scale Effect of Flexural Strength of Steel Fiber Reinforced Recycled Concrete

SU Jie1，2，QIN Hongjie1，SHI Caijun1，2，FANG Zhi1

（1. Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province，Hunan University，Changsha 410082，China；2. College of Civil Engineering，Hunan University，Changsha 410082，China）

Abstract：The four-point bending test of 5 groups of recycled aggregate substitute rates and 4 groups of steel fiber reinforced recycled aggregate concrete prism specimens were conducted to study the effects of recycled aggregate substitution rate and steel fiber content on the flexural strength and the scale effect of recycled concrete. The test re-sults show that there is scale effect in the flexural strength of each kind of prism specimens. With the increase of the substitution rate of recycled aggregate， the scale effect of the flexural strength of recycled concrete increases first and then decreases. The scale effect of the flexural strength of the specimen with a substitution rate of 75% is about 1.32 times and 1.09 times that of the specimens with a substitution rate of 0 and 100%， respectively. The content of steel fiber has a certain effect on the scale effect of the flexural strength of recycled concrete. When the steel fiber content ranges from 0% to 0.75%， the larger the content of steel fiber， the more pronounced the scale effect is. The scale effect of specimens with steel fiber content of 0， 0.25% and 0.5% is about 79%， 85% and 94% of the specimen with steel fiber content of 0.75%， respectively. When the steel fiber content is over 0.75%，the variation on the scale effect of flexural strengthwithdifferentsteelfibercontentsislimited.Thescaleeffectofthespecimenwithsteelfibercontent0.75%isabout 99% of the specimen with fiber content of 1%. A calculation formula for the scale effect law of the flexural strength of recycled concrete is proposed，which can be used to analyze the flexural strength of recycled concrete.

Key words：recycled aggregate concrete；flexural strength；scale effect；steel fiber；substitute rate

通过破碎废旧混凝土得到的再生骨料由于内部存在微裂缝和表面残留有砂浆，其物理性质离散性通常较天然骨料更大[1]，由此导致再生骨料混凝土各方面物理力学性能与普通混凝土相比存在一定差异.力学性能的尺寸效应是再生混凝土材料的固有特征[2]，通常认为尺寸……