题 目： 评估和验收混凝土
系 别： 土木工程系 专业班级： 土木153 姓 名： 黄志豪 学 号： 20151864 指导教师： 张婉霞
二〇一八年一月十日
CODE
5.6 — Evaluation and acceptance of concrete
5.6.1 — Concrete shall be tested in accordance with the requirements of 5.6.2 through 5.6.5. The testing agency performing acceptance testing shall comply with ASTM C1077. Qualified field testing technicians shall perform tests on fresh concrete at the job site,prepare specimens required for curing under field conditions, prepare specimens required for testing in the laboratory, and record the temperature of the fresh concrete when preparing specimens for strength tests. Qualified laboratory technicians shall perform all required laboratory tests. All reports of acceptance tests shall be provided to the licensed design professional, contractor, concrete producer, and, when requested, to the owner and the building official.
5.6.2 — Frequency of testing
5.6.2.1 — Samples for strength tests of each class of concrete placed each day shall be taken not less than once a day, nor less than once for each 110 m3 of concrete, nor less than once for each 460 m2 of surface area for slabs or walls.
5.6.2.2 — On a given project, if total volume of concrete is such that frequency of testing required by 5.6.2.1 would provide less than five strength tests for a given class of concrete, tests shall be made from at least five randomly selected batches or from each batch if fewer than five batches are used.
5.6.2.3 — When total quantity of a given class of concrete is less than 38 m3, strength tests are not required when evidence of satisfactory strength is submitted to and approved by the building official.
5.6.2.4 — A strength test shall be the average of the strengths of at least two
150 by 300 mm cylinders or at least three 100 by 200 mm cylinders made from the same sample of concrete and tested at 28 days or at test age designated for determination of fc′ .
5.6.3 — Standard-cured specimens
5.6.3.1 — Samples for strength tests shall be taken in accordance with ASTM C172.
5.6.3.2 — Cylinders for strength tests shall be molded and standard-cured in accordance with ASTM C31M and tested in accordance with ASTM C39M. Cylinders shall be 100 by 200 mm or 150 by 300 mm.
5.6.3.3 — Strength level of an individual class of concrete shall be considered satisfactory if both of the following requirements are met:
(a) Every arithmetic average of any three consecutive strength tests (see 5.6.2.4) equals or exceeds fc′ ;
(b) No strength test (see 5.6.2.4) falls below fc′ by more than 3.5 MPa when fc′ is 35 MPa or less; or by more than 0.10fc′ when fc′ is more than 35 MPa.
5.6.3.4 — If either of the requirements of 5.6.3.3 is not met, steps shall be taken to increase the average of subsequent strength test results. Requirements of 5.6.5 shall be observed if requirement of 5.6.3.3(b) is not met.
5.6.4 — Field-cured specimens
5.6.4.1 — If required by the building official, results of strength tests of cylinders cured under field conditions shall be provided.
5.6.4.2 — Field-cured cylinders shall be cured under field conditions in accordance with ASTM C31M.
5.6.4.3 — Field-cured test cylinders shall be molded at the same time and from the same samples as laboratory-cured test cylinders.
5.6.4.4 — Procedures for protecting and curing concrete shall be improved when strength of field cured cylinders at test age designated for determination of fc′ is less than 85 percent of that of companion laboratory-cured cylinders. The 85 percent limitation shall not apply if field-cured strength exceeds fc′ by more than 3.5 MPa.
5.6.5 — Investigation of low-strength test results
5.6.5.1 — If any strength test (see 5.6.2.4) of laboratory-cured cylinders falls below fc′ by more than the values given in 5.6.3.3(b) or if tests of field-cured cylinders indicate deficiencies in protection and curing (see 5.6.4.4), steps shall be taken to ensure that load carrying capacity of the structure is not jeopardized.
5.6.5.2 — If the likelihood of low-strength concrete is confirmed and calculations indicate that load-carrying capacity is significantly reduced, tests of cores drilled from the area in question in accordance with ASTM C42M shall be permitted. In such cases, three cores shall be taken for each strength test that falls below the values given in 5.6.3.3(b).
5.6.5.3 — Cores shall be obtained, moisture conditioned by storage in watertight bags or containers, transported to the laboratory, and tested in accordance with ASTM C42M. Cores shall be tested no earlier than 48 hours and not later than 7 days after coring unless approved by the licensed design professional. The specifier of tests referenced in ASTM C42M shall be the licensed design professional.
5.6.5.4 — Concrete in an area represented by core tests shall be considered
structurally adequate if the average of three cores is equal to at least 85 percent of fc′ and if no single core is less than 75 percent of fc′ . Additional testing of cores extracted from locations represented by erratic core strength results shall be permitted.
5.6.5.5 — If criteria of 5.6.5.4 are not met and if the structural adequacy remains in doubt, the responsible authority shall be permitted to order a strength evaluation in accordance with Chapter 20 for the questionable portion of the structure, or take other appropriate action.
5.6.6 — Steel fiber-reinforced concrete
5.6.6.1 — Acceptance of steel fiber-reinforced concrete used in beams in accordance with 11.4.6.1(f) shall be determined by testing in accordance with ASTM C1609M. In addition, strength testing shall be in accordance with 5.6.1.
5.6.6.2 — Steel fiber-reinforced concrete shall be considered acceptable for shear resistance if conditions (a), (b), and (c) are satisfied:
(a) The weight of deformed steel fibers per cubic meter of concrete is greater than or equal to 60 kg.
(b) The residual strength obtained from flexural testing in accordance with ASTM C1609M at a midspan deflection of 1/300 of the span length is greater than or equal to 90 percent of the measured first-peak strength obtained from a flexural test or 90 percent of the strength corresponding to fr from Eq. (9-10), whichever is larger; and
(c) The residual strength obtained from flexural testing in accordance with ASTM C1609M at a midspan deflection of 1/150 of the span length is greater than or equal to 75 percent of the measured first-peak strength obtained from a flexural test or 75 percent of the strength corresponding to fr from Eq. (9-10), whichever is larger.
COMMENTARY
R5.6 — Evaluation and acceptance of concrete
Once the mixture proportions have been selected and the job started, the criteria for evaluation and acceptance of the concrete can be obtained from 5.6.
An effort has been made in the Code to provide a clear-cut basis for judging the acceptability of the concrete, as well as to indicate a course of action to be followed when the results of strength tests are not satisfactory.
R5.6.1 — ASTM C10775.3 identifies and defines the duties and minimum technical requirements and qualifications of testing laboratory personnel and requirements for testing concrete and concrete aggregates used in construction. Inspection and accreditation of testing laboratories is a process that ensures that they conform to ASTM C1077. Laboratory and field technicians can establish qualifications by becoming certified through certification programs. Field technicians in charge of sampling concrete; testing for slump, density, yield, air content, and temperature; and making and curing test specimens should be certified in accordance with the requirements of ACI Concrete Field Testing Technician—Grade 1 Certification Program, or an equivalent program. Concrete testing laboratory personnel should be certified in accordance with the requirements of ACI Concrete Laboratory Testing Technician, or Concrete Strength Testing Technician. The Code requires testing reports to be distributed to the parties responsible for the design, construction, and approval of the work. Such distribution of test reports should be indicated in contracts for inspection and testing services. Prompt distribution of testing reports allows for timely identification of either compliance or the need for corrective action. A complete record of testing allows the concrete producer to reliably establish the required average strength fcr′ for future work.
R5.6.2 — Frequency of testing
R5.6.2.1 — The following three criteria establish the required minimum sampling frequency for each class of concrete:
(a) Once each day a given class is placed, nor less than
(b) Once for each 110 m3 of each class placed each day, nor less than (c) Once for each 460 m2 of slab or wall surface area placed each day.
In calculating surface area, only one side of the slab or wall should be considered. Criteria (c) will require more frequent sampling than once for each 110 m3 placed if the average wall or slab thickness is less than 240 mm.
R5.6.2.2 — Samples for strength tests are to be taken on a strictly random basis if they are to measure properly the acceptability of the concrete. To be representative, the choice of times of sampling, or the batches of concrete to be sampled, are to be made on the basis of chance alone, within the period of placement. Batches should not be sampled on the basis of appearance, convenience, or other possibly biased criteria, because the statistical analyses will lose their validity. Not more than one test (as defined in 5.6.2.4) should be taken from a single batch, and water may not be added to the concrete after the sample is taken. ASTM D36655.4 describes procedures for random selection of the batches to be tested.
R5.6.2.4 — More than the minimum number of specimens may be desirable to allow for discarding an outlying individual cylinder strength in accordance with ACI 214R.5.5 When individual cylinder strengths are discarded in accordance with ACI 214R, a strength test is valid provided at least two individual 150 by 300 mm cylinder strengths or at least three 100 by 200 mm cylinders are averaged. All individual cylinder strengths that are not discarded in accordance with ACI 214R are to be used to calculate the average strength. The size and number of specimens representing a strength test should remain constant for each class of concrete.
Testing three 100 by 200 mm cylinders preserves the confidence level of the average strength because 100 by 200 mm cylinders tend to have approximately 20 percent higher within-test variability than 150 by 300 mm cylinders.5.6 R5.6.3 — Standard-cured specimens R5.6.3.2 — The cylinder size should be agreed upon by the owner, licensed design professional, and testing agency before construction.
R5.6.3.3 — A single set of criteria is given for accept ability of strength and is applicable to all concrete used in structures designed in accordance with the Code, regardless of design method used. The concrete strength is considered to be satisfactory as long as averages of any three consecutive strength tests remain above the specified fc′ and no individual strength test falls below the specified fc′ by more than 3.5 MPa if fc′ is 35 MPa or less, or falls below fc′ by more than 10 percent if fc′ is over 35 MPa. Evaluation and acceptance of the concrete can be judged immediately as test results are received during the course of the Work. Strength tests failing to meet these criteria will occur occasionally (probably about once in 100 tests) even though concrete strength and uniformity are satisfactory. Allowance should be made for such statistically expected variations in deciding whether the strength level being produced is adequate.
R5.6.3.4 — When concrete fails to meet either of the strength requirements of 5.6.3.3, steps should be taken to increase the average of the concrete test results. If sufficient concrete has been produced to accumulate at least 15 tests, these should be used to establish a new target average strength as described in 5.3.
If fewer than 15 tests have been made on the class of concrete in question, the new target strength level should be at least as great as the average level used in the initial selection of proportions. If the average of the available tests made on the project equals or exceeds the level used in the initial selection of proportions, a further increase in average level is required. The steps taken to increase the average level of test results will depend on the particular
circumstances, but could include one or more of the following: (a) An increase in cementitious materials content; (b) Changes in mixture proportions;
(c) Reductions in or better control of levels of slump supplied; (d) A reduction in delivery time; (e) Closer control of air content;
(f) An improvement in the quality of the testing, including strict compliance with standard test procedures.
Such changes in operating and testing procedures, or changes in cementitious materials content, or slump should not require a formal resubmission under the procedures of 5.3; however, important changes in sources of cement, aggregates, or admixtures should be accompanied by evidence that the average strength level will be improved.
Laboratories testing cylinders or cores to determine compliance with these requirements should be accredited or inspected for conformance to the requirement of ASTM C10775.3 by a recognized agency such as the American Association for Laboratory Accreditation (A2LA), AASHTO Materials Reference Laboratory (AMRL), National Voluntary Laboratory Accreditation Program (NVLAP), Cement and Concrete Reference Laboratory (CCRL), or their equivalent.
R5.6.4 — Field-cured specimens
R5.6.4.1 — Strength tests of cylinders cured under field conditions may be required to check the adequacy of curing and protection of concrete in the structure.
R5.6.4.4 — Positive guidance is provided in the Code concerning the interpretation of tests of field-cured cylinders. Research has shown that cylinders protected and cured to simulate good field practice should test not
less than about 85 percent of standard laboratory moist-cured cylinders. This percentage has been set as a rational basis for judging the adequacy of field curing. The comparison is made between the actual measured strengths of companion field cured and laboratory-cured cylinders, not between field cured cylinders and the specified value of fc′ . However, results for the field-cured cylinders are considered satisfactory if the field-cured cylinders exceed the specified fc′ by more than 3.5 MPa, even though they fail to reach 85 percent of the strength of companion laboratory-cured cylinders.
R5.6.5 — Investigation of low-strength test results
Instructions are provided concerning the procedure to be followed when strength tests have failed to meet the specified acceptance criteria. These instructions are applicable only for evaluation of in-place strength at time of construction. Strength evaluation of existing structures is covered by Chapter 20. The building official should apply judgment as to the significance of low test results and whether they indicate need for concern. If further investigation is deemed necessary, such investigation may include nondestructive tests or, in extreme cases, strength tests of cores taken from the structure.
Nondestructive tests of the concrete in place, such as by probe penetration, impact hammer, ultrasonic pulse velocity or pullout may be useful in determining whether or not a portion of the structure actually contains low-strength concrete. Such tests are of value primarily for comparisons within the same job rather than as quantitative measures of strength. For cores, if required, conservatively safe acceptance criteria are provided that should ensure structural adequacy for virtually any type of construction.5.7-5.10 Lower strength may, of course, be tolerated under many circumstances, but this again becomes a matter of judgment on the part of the building official and licensed design professional. When the core tests performed in accordance with 5.6.5.4 fail to provide assurance of structural adequacy, it may be practical, particularly in the case of floor or
roof systems, for the building official to require a load test (Chapter 20). Short of load tests, if time and conditions permit, an effort may be made to improve the strength of the concrete in place by supplemental wet curing. Effectiveness of such a treatment should be verified by further strength evaluation using procedures previously discussed.
The use of a water-cooled bit results in a core with a moisture gradient between the exterior surface and the interior. This gradient lowers the apparent compressive strength of the core.5.11 The restriction on the commencement of core testing provides a minimum time for the moisture gradient to dissipate. The maximum time between coring and testing is intended to ensure timely testing of cores when strength of concrete is in question. Research5.11 has also shown that procedures for soaking or drying cores that were required before ACI 318-02 affect measured compressive strength and result in conditions that are not
representative of structures that are dry or wet in service. Thus, to provide reproducible moisture conditions that are representative of in-place conditions, a common moisture conditioning procedure that permits dissipation of moisture gradients is prescribed for cores. ASTM C42M permits the specifier of tests to modify the default duration of moisture conditioning before testing.
Core tests having an average of 85 percent of the specified strength are realistic. To expect core tests to be equal to fc′ is not realistic, since differences in the size of specimens,conditions of obtaining samples, and procedures for curing, do not permit equal values to be obtained.
The Code, as stated, concerns itself with assuring structural safety, and the instructions in 5.6 are aimed at that objective. It is not the function of the Code to assign responsibility for strength deficiencies, whether or not they are such as to require corrective measures.
Under the requirements of this section, cores taken to confirm structural adequacy will usually be taken at ages later than those specified for determination of
fc′ .
R5.6.6 — Steel fiber-reinforced concrete
R5.6.6.1 — The performance criteria are based on results from flexural tests5.12 conducted on steel fiber-reinforced concretes with fiber types and contents similar to those used in the tests of beams that served as the basis for 11.4.6.1(f).
R5.6.6.2(b),(c) — The term “residual strength” is defined in ASTM C1609M.
规范条例
5.6-评估和验收混凝土
5.6.1-混凝土应按照规范5.6.2至5.6.5的要求。测试执行验收测试的机构应遵守符合规范ASTM C1077。合格的现场测试技术人员应在施工现场对新浇混凝土进行试验，准备现场养护所需的样品条件，制备试验所需的样品实验室，并记录新样品的温度准备强度试验用做试样时混凝土。合格的实验室技术人员应要求的实验室试验。所有验收报告应向许可设计提供试验。专业人员、承包商、混凝土生产商，以及，当业主和建筑官员要求时。
5.6.2-测试频率
5.6.2.1-各等级强度试验用样品每天浇筑的混凝土应不少于，每110立方米混凝土，每460 m2板或墙的表面积，每天不少于一次。
5.6.2.2-在给定项目上，如果混凝土应满足以下要求：按5.6.2.1将提供5次以下的强度试验，给定等级的混凝土应在至少五个随机选择的批次或每个批次，使用的批次少于五个。
5.6.2.3-当给定类别的总数量混凝土小于38m3，强度试验不当满足强度的检测时提交建筑官员批准。
5.6.2.4-强度试验应为至少两个150×300 mm圆柱体或至少三个由同一混凝土样品，养护28天用于测定fc′的试验时间。
5.6.3-标准固化试样
5.6.3.1-采集强度试验用样品，应符合ASTM C172。
5.6.3.2-强度试验用气缸应按照ASTM标准进行成型和标准固化，并根据ASTM C39M进行测试。规格应为100×200 mm或150×300 mm。
5.6.3.3-如果满足以下要求。单个类别的强度等级混凝土应被视为合格： （a）任何连续三次的算术平均数强度试验（见5.6.2.4）等于或超过fc’；
（b）强度试验（见5.6.2.4）不低于fc通过fc时大于3.5兆帕'等于或小于35兆帕；或当fc′大于35MPa时大于0.10fc′。
5.6.3.4-如果5.6.3.3的任一要求不满足，应采取措施增加平均值。后续强度试验结果。要求5.6.5如果5.6.3.3（b）的要求是不满足。
5.6.4-现场固化试样
5.6.4.1-如果建筑官员要求，应提供现场条件下养护的圆柱体强度试验结果。
5.6.4.2-现场固化气瓶应根据ASTM C31M在现场条件下进行固化。
5.6.4.3-现场固化试验气缸应与实验室固化试验气缸同时成型，并采用相同的样品。
5.6.4.4-当指定用于测定fc′的试验年龄的现场养护圆柱体的强度小于配套实验室养护圆柱体强度的85%时，应改进保护和养护混凝土的程序。如果现场固化强度超过fc′，则85%的限制不适用大于3.5兆帕。
5.6.5-低强度试验结果调查
5.6.5.1-如果有以下强度试验（见5.6.2.4）实验室固化的试块低于fc′，比5.6.3.3（b）中给出的值或现场固化试验的值，试块显示保护和固化不足（见5.6.4.4），应采取措施确保结构的承载能力不受损害。
5.6.5.2-如果低强度混凝土的可能性为确认和计算表明钻取岩心的测试大大降低了产能。根据美国材料试验与试验协会的要求，应允许使用C42M。在这种情况下，三个核心应进行以下强度试验5.6.3.3（b）中给出的值。
5.6.5.3-应获得取样，通过将其存放在防水袋或容器中调节湿度，运至实验室，并按照ASTM C42M进行测试。应测试芯超过48小时但不迟于7天后取芯，除非获得授权设计专业人员的批准。ASTM中引用的试验规范c42m应为持牌设计专业人员。
5.6.5.4-如果三个混凝土芯的平均值至少等于fc′的85%，并且如果没有单个混凝土芯小于fc′的75%，则应认为混凝土在芯样试验所代表的区域内具有足够的结构。应允许对从不稳定的芯强度结果代表的位置提取的芯样进行额外试验。
5.6.5.5-如果不符合5.6.5.4的标准，并且结构的充分性仍有疑问，则应允许责任机构根据第20章的规定，对有疑问的材料进行强度评估。结构的一部分，或采取其他适当的措施。
5.6.6-钢纤维混凝土
5.6.6.1-钢纤维加固的验收梁用混凝土符合11.4.6.1（f）应根据ASTM C1609M。此外，强度试验应根据5.6.1。
5.6.6.2-钢纤维混凝土应满足条件（a）、（b）和（c），则认为抗剪强度满足要求： （a）每立方米混凝土中变形钢纤维的重量大于或等于60千克。
（b）从弯曲中获得的残余强度根据ASTM C1609M在a跨中挠度为跨度长度的1/300大于或等于测量值的90%弯曲试验获得的第一峰值强度或与fr对应的强度的90%式（9-10），以较大者为准。
（c）从弯曲中获得的残余强度根据ASTM C1609M在a跨中挠度为跨长的1/150大于或等于测量值的75%弯曲试验获得的第一峰值强度或75%的强度对应于式（9-10），以较大者为准。
注释
R5.6-评估和验收混凝土
一旦选择了混合比例和作业开始，评估和验收混凝土的标准可从规范5.6中获得。
该准则已作出规定，以提供一个明确的判断混凝土可接受性的依据，以便判断结果强度试验不合格。
R5.6.1-确定和定义职责最低技术要求和资格试验室人员和试验要求建筑用混凝土和混凝土集料。检测实验室的检验和认可是确保其符合ASTM C1077的工艺。实验室和现场技术人员可以给予合格证书通过认证计划获得认证。现场混凝土取样技术员测试坍落度、密度、产量、含气量和温度；以及制作和养护试样应符合ACI混凝土领域的要求，测试技术员一级认证计划，或等效证件。混凝土试验室人员应按照以下要求进行认证：ACI混凝土实验室测试技术员，或混凝土强度测试技术员。
规范要求将测试报告分发到负责设计、施工和工程管理的地方。测试报告的分发应在检验和测试合同中注明服务。测试报告的及时分发允许及时确定合规性或需要纠正措施。完整的测试记录允许可靠确定所需平均值的混凝土生产商为将来的工作提供材料。
R5.6.2-测试频率
R5.6.2.1-以下三个标准确定了每类混凝土所需的最小取样频率： （a）：每天一次，且不少于
（b）：每110立方米一次，每天一次，也不少于 （c）：板或墙表面积，每460 m2一次，每天一次
在计算表面积时，板或墙的一侧应该考虑。标准（c）要求更频繁，如果墙或板厚度小于240 mm， 平均每110立方米取样一次
R5.6.2.2-强度试验的样品应要正确测量混凝土的可接受性。作为样品，选择取样次数，或混凝土批次抽样，仅在机会的基础上进行，在安置期。不应在外观、方便或其他可能的基础有偏见的标准，因为这样统计分析将失去有效性。不超过一次试验（如5.6.2.4所定义）应该从一个批次中提取，而水不能在取样后加入混凝土中。ASTM D36655.4描述了随机选择的方法要测试的批次。
R5.6.2.4-超过最小样本数可能需要考虑根据ACI 214R.5.5不要外部单个试块强度。当单个试块的强度在ACI 214R范围，提供的强度试验有效。至少两个单独的150×300 mm圆柱体强度或平均至少三个100×200 mm的圆柱体。所有未根据ACI 214R舍弃的单个试块强度将用于计算平均值。代表每种混凝土的强度试验应保持不变。测试三个100×200 mm的圆柱体可以保持平均强度的置信水平，因为100×200 mm试块通常会高出大约20%。试验变异性大于150×300 mm试块
R5.6.3-标准固化试样
R5.6.3.2-试块尺寸应由业主、授权设计专业人员和测试机构施工前做好。
R5.6.3.3-给出了强度可接受性的单一标准集，适于用按照规范设计的结构，无论采用什么的设计方法。考虑混凝土强度只要连续三次的平均值令人满意，强度试验保持在规定的fc以上'没有一次强度试验低于规定的fc'超过3.5兆帕如果fc'等于或小于35兆帕，或低于fc'超过10如果fc'超过35兆帕。可以立即评估和验收判断混凝土，因为试验结果在工作过程中收到。强度试验失败为了满足这些标准，偶尔会发生。即使混凝土强度和均匀性令人满意。应考虑在决定是否所产生的强度水平足够。
R5.6.3.4-当混凝土未能满足5.6.3.3的强度要求，应采取步骤。增加混凝土试验结果的平均值。如果满足要求生产混凝土，至少可进行15次试验，这些应用于建立新的目标平均值。强度如5.3所述。
如果对所讨论的混凝土等级进行的试验少于15次，则新的目标强度等级应至少与最初选择比例时使用的平均等级相同。如果项目可用测试的平均值等于或超过最初选择比例时使用的水平，则需要进一步增加平均水平。
提高测试结果平均水平所采取的步骤取决于具体情况，但可以包括以下一项或多项： （a）胶凝材料含量增加； （b）混合物比例的变化；
（c）降低或更好地控制坍落度水平； （d）交货时间缩短；
（e）更密切地控制空气含量；
（f）测试质量的改进，包括严格遵守标准试验程序。
操作和试验程序的此类变更，或水泥基材料含量或坍落度的变更不应要求按照第5.3节的程序进行正式重新提交；但是，水泥、骨料或掺合料来源的重要变更应伴随平均强度水平将得到提高的保证。
实验室测试试块或芯以确定符合这些要求应得到认证或检查是否符合ASTM要求C10775.3由美国等公认机构提供实验室认可协会（A2LA），美国国家公路与运输协会材料参考实验室（AMRL），国家自愿实验室认证计划（NVLAP），水泥和混凝土参考实验室（CCRL），或其等效机构。
R5.6.4-现场固化试样
R5.6.4.1-现场养护的圆柱体强度试验可能需要条件来检查固化的充分性，以保护结构中的混凝土。
R5.6.4.4-规范中提供了积极的指导关于现场固化气瓶试验的解释。研究表明，试块的保护和固化模拟良好的现场实践应测试不少于85%的标准实验室湿固化气瓶。这个百分比被设定为判断的合理依据。
现场养护的充分性。进行了比较在现场固化和实验室固化气瓶的实际测量强度之间，而不是在现场固化气瓶和规定值fc之间“这是一个很好的例子。然而，如果现场固化圆柱体超过规定的fc，则认为现场固化圆柱体的结果令人满意。超过3.5兆帕，即使达不到85%配套实验室固化气瓶的强度。
R5.6.5-低强度试验结果调查
提供了关于以下程序的说明：当强度试验不符合规定时，应遵循验收标准。这些说明仅适用于施工时现场强度评估。现有结构的强度评估包括第20章。建筑官员应将判决作为低测试结果的重要性以及它们是否表示需要关注。如果进一步调查被认为必要时，此类调查可能包括非破坏性的测试，或在极端情况下，对取自结构。
对现场混凝土进行无损检测，如探头穿透、冲击锤、超声波脉冲速度或者在确定是否结构的一部分实际上含有低强度混凝土。这些测试主要用于比较。在同一份工作中而不是作为主要。对于核心，如果需要，保守安全验收提供的标准应确保结构的充分性。几乎适用于任何类型的结构。5.7-5.10低强度当然，在很多情况下都是可以容忍的，但是这再次成为一个判断问题的一部分建筑官员和持牌设计专业人士。当根据5.6.5.4进行的堆芯试验未能确保结构的充分性，这可能是可行的，特别是在地板或屋顶系统的情况下，建筑官员需要进行负载测试（第20章）。缺少负载测试，如果时间和条件允许，可以通过以下方法提高现浇混凝土的强度：补充湿养护。这种治疗的有效性应通过进一步的强度评估来验证 之前讨论过的程序。
使用水冷钻头会导致岩心受潮。外表面和内表面之间的渐变。这个梯度降低了混凝土的表观抗压强度。堆芯5.11堆芯开工限制测试为湿度梯度提供了最短时间消散。取芯和测试之间的最长时间旨在确保在强度较高时及时测试芯样。关于混凝土的问题。研究5.11还表明浸泡或干燥所需芯样的程序ACI 318-02之前影响测量的抗压强度导致不代表使用中干燥或潮湿的结构。因此，提供具有代表性的可再现水分条件现场条件下，常见的湿度调节允许水分梯度消散的程序是为核心规定。ASTM C42M允许修改湿度调节默认持续时间的测试前。
平均强度为规定强度85%的堆芯试验是现实的。期望芯样试验等于fc′是不现实的，因为试样尺寸、取样条件和固化程序的差异不允许获得相同的值。
如前所述，规范本身与确保结构安全有关，5.6中的说明旨在实现这一目标。规范的职能不是为强度缺陷指定责任，无论这些缺陷是否需要采取纠正措施。
根据本节的要求，为确认结构充分性而取芯样的取芯时间通常比确定fc′规定的取芯时间晚。
R5.6.6-钢纤维混凝土
R5.6.6.1-性能标准基于结果根据在钢纤维增强材料上进行的弯曲试验5.12，纤维类型和含量与所用纤维相似的混凝土在作为11.4.6.1（f）基础的梁的试验中。
R5.6.6.2（b），（c）-术语“剩余强度”定义如下：在ASTM C1609M中。
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