3.1 This test method provides standardized procedures for obtaining and testing specimens to determine the compressive, splitting tensile, and flexural strength of in-place concrete.
3.2 Generally, test specimens are obtained when doubt exists about the in-place concrete quality due either to low strength test results during construction or signs of distress in the structure. Another use of this method is to provide strength information on older structures.
3.3 Concrete strength is affected by the location of the concrete in a structural element, with the concrete at the bottom tending to be stronger than the concrete at the top. Core strength is also affected by core orientation relative to the horizontal plane of the concrete as placed, with strength tending to be lower when measured parallel to the horizontal plane.3 These factors shall be considered in planning the locations for obtaining concrete samples and in comparing strength test results.
3.4 The strength of concrete measured by tests of cores is affected by the amount and distribution of moisture in the specimen at the time of test. There is no standard procedure to condition a specimen that will ensure that, at the time of test, it will be in the identical moisture condition as concrete in the structure. The moisture conditioning procedures in this test method are intended to provide reproducible moisture conditions that minimize within-laboratory and between-laboratory variations and to reduce the effects of moisture introduced during specimen preparation.
3.5 The measured compressive strength of a core will generally be less than that of a corresponding properly molded and cured standard cylinder tested at the same age. For a given concrete, however, there is no unique relationship between the strengths of these two types of specimens (see Note 3). The relationship is affected by many factors such as the strength level of the concrete, the in-place temperature and moisture histories, the degree of consolidation, batch-to-batch variability, the strength-gain characteristics of the concrete, the condition of the coring apparatus, and the care used in removing cores.
Note 3: A procedure is available for estimating the equivalent cylinder strength from a measured core strength.4
Note 4: In the absence of core strength requirements of an applicable building code or of other contractual or legal documents that may govern the project, the specifier of tests should establish in the project specifications the acceptance criteria for core strengths. An example of acceptance criteria for core strength is provided in ACI 318,5 which are used to evaluate cores taken to investigate low strength test results of standard-cured cylinder during construction. According to ACI 318, the concrete represented by the cores is considered structurally adequate if the average strength of three cores is at......
氯离子是诱发钢筋锈蚀的重要因素,为了避免钢筋过早锈蚀,混凝土原材料中氯离子含量的控制相当严格。我国部分规范明确要求混凝土在选配砂子、骨料、水泥、外加剂、拌和水等混凝土原材料的时候,必须进行氯离子含量的测试,从根本上避免将过量氯离子带入混凝土中。 标准简介 根据水利技术标准制修订工作安排,按照SL 1-2014《水利技术标准编写规定》, 对SL 352-2006《水工混凝土试验规程》 进行修订。...
停钻的要求是:先关机器后关水,若是深孔时,还不能立即提钻和停水,而要用水冲孔一段时间,目的在于将孔内的岩粉冲洗干净,以防岩粉沉淀导致埋钻,造成取芯困难。 混凝土钻孔取芯机简介: 该产品为HZ系列金钢石工程钻机之一。采用汽油发动机为动力(进口本田原装)启动快捷,操作简便,运转可靠,适用于无电力场所和较大口径的工程钻孔。 ...
注:7个有效的试验结果就可以计算出偏斜系数,但考虑到有无效试验情况,建议至少取10根试样。A.2.2 试样长度应满足试样进行拉伸和锚固用。A.2.3 试样除被切割外不能进行任何的加工处理。...
所以工地上混凝土的取样如果不是按规定的数量随机抽取,而是根据混凝土搅拌质量的好坏来取,质量好的时候才取样,所取的样品就没有代表性,不能真实反映混凝土的质量情况。 2、钻芯法,是在有代表性的混凝土结构上用金钢石钻头钻取芯样,经过加工,两端锯切、磨平或补平后,制作成圆柱体进行抗压强度测定。...
Copyright ©2007-2022 ANTPEDIA, All Rights Reserved
京ICP备07018254号 京公网安备1101085018 电信与信息服务业务经营许可证:京ICP证110310号