(1 上海市建筑科学研究院有限公司, 上海 200032;2 上海市工程结构安全重点实验室, 上海 200032)

摘要: 现场检测混凝土强度的推定值同时受到样本强度平均值和标准差的影响,而不同测试方式下样本强度标准差的差异很大. 对立方体、圆柱体两种同条件养护试块和回弹法、钻芯法两种方法检测混凝土强度的平均值和标准差进行对比试验,同时研究了芯样直径、高径比、粗骨料表面积占比等因素对芯样强度平均值和标准差的影响. 试验结果表明,与同条件养护立方体试块相比,芯样强度的平均值偏大,标准差略偏大;回弹强度的平均值偏小,标准差明显偏小;ϕ150、ϕ105、ϕ75 三种芯样中,相对于 ϕ105 芯样,ϕ150 芯样的强度平均值偏小,而 ϕ75 芯样的强度标准差偏大;小高径比芯样与标准芯样的强度平均值之间有较明确的换算关系,而前者的强度标准差略小于后者,故小高径比芯样仍有较大的利用价值;芯样强度标准差表现出随外露粗骨料尤其是大粒径粗骨料表面积占比增大而增大的趋势,这可以解释芯样强度标准差相对于立方体试块强度标准差偏大的原因.

关键词: 混凝土抗压强度; 回弹法; 钻芯法; 芯样直径; 高径比; 粗骨料表面积占比

中图分类号:TU528. 1 文献标志码:A 文章编号:1002⁃848X(2022)08⁃0105⁃07

DOI:10. 19701 / j.jzjg.LS202101

Comparative experimental research on concrete compression strength under different testing methods

ZHENG Shiju1,2, LIU Hui1,2, JIANG Lixue1,2

(1 Shanghai Research Institute of Building Sciences Co., Ltd., Shanghai 200032, China; 2 Shanghai Key Laboratoryof Engineering Structure Safety, Shanghai 200032, China)

Abstract: The presumed value of concrete strength tested on site is affected by both the mean value and standard deviationof the sample strength, and the standard deviation of the sample strength varies greatly under different testing methods. Themean value and standard deviation of the concrete strength of the cube and cylinder test blocks under the same conditions ofcuring as well as the rebound method and the core drilling method were compared. The influence of core sample diameter,height⁃diameter ratio and surface area ratio of coarse aggregate on the mean value and standard deviation of the samplestrength of testing samples was also studied. The test results show that, compared with cube test block under the sameconditions of curing, the mean value of core sample strength is larger and the standard deviation is slightly larger. The meanvalue of the rebound strength is smaller and the standard deviation is obviously smaller. Among ϕ150、ϕ105 and ϕ75 coresamples, when compared with the ϕ105 core sample, the mean strength of the ϕ150 core sample is smaller and the strengthstandard deviation of the ϕ75 core sample is larger. There is a clear conversion relationship between the mean strengths ofthe core samples with small height⁃diameter ratio and standard core samples, and the strength standard deviation of theformer is slightly smaller than that of the latter, so the core sample with small height⁃diameter ratio still has a considerableapplication value. The standard deviation of core sample strength shows a growth trend with the increase of the surface arearatio of exposed coarse aggregate, especially large particle size coarse aggregate, which can explain the reason why thestandard deviation of the core sample strength is larger than that of the cube test block.

Keywords:concrete compression strength; rebound method; core drilling method; core sample diameter; height⁃diameterratio; surface area ratio of coarse aggregate

∗国家重点研发计划项目(2017YFC0806100),上海市科学技术委员会项目(19DZ1202400).

第一作者:郑士举,硕士,高级工程师,一级注册结构工程师,主要从事既有建筑鉴定与加固研究,Email:zsj85408048@ 163.com.

[引用本文] 郑士举,刘辉,蒋利学. 不同测试方式下混凝土抗压强度对比试验研究[ J]. 建筑结构,2022,52(8):105⁃111. ZHENG Shiju, LIU Hui, JIANG Lixue. Comparative experimental research on concrete compression strengthunder different testing methods[J]. Building Structure,2022,52(8):105⁃111.