People's Republic of China industry standard
Technical specification for rebound concrete testing for compressive strength of concrete JGJ-T23-92
Compiling institute: Shaanxi Provincial Architectural Science Research and Design Institute
Approval Department: Ministry of Construction of the People's Republic of China
Date of implementation: October 1, 1993
About the release of industry standards "rebound method for testing concrete
Notice of Technical Specifications for Compressive Strength
Jianbiao [1993] No. 385, according to the requirements of the original Ministry of Environmental Protection and Environmental Protection (88) City Standard No. 141, the Technical Regulations for Testing Concrete Compressive Strength by the Rebound Method, edited by Shaanxi Provincial Architectural Science Research and Design Institute, After review, it is now approved as an industry standard, number JGJ/T23-92, effective as of October 1, 1993.
This regulation is managed by the China Academy of Building Research, which is the standard of construction engineering standard technology of the Ministry of Construction. The specific explanation and other work are the responsibility of the Shaanxi Provincial Institute of Architectural Science and Design. Organized and published by the Institute of Standards and Ratings of the Ministry of Construction.
Ministry of Construction
May 18, 1993
Content
Main symbol
1 General
2 rebound
2.1 Technical requirements
2.2 Verification
2.3 Maintenance
3 Detection technology
3.1 General provisions
3.2 rebound value measurement
3.3 Carbonization depth measurement
4 rebound value calculation
5 strength curve
5.1 General provisions
5.2 Unified strength curve
5.3 Regional and special strength curves
6 Calculation of concrete strength
Appendix A Test Report
Appendix B Method for formulating special strength curve
Appendix C: Correction value of rebound value in non-horizontal state detection
Appendix D Correction value of rebound value for different pouring surfaces
Appendix E Measurement Area Concrete Strength Conversion Table
Appendix F Rebound Method Detection Original Record Form
Appendix G Component Concrete Strength Calculation Table
Appendix H Description of the terms used in this procedure
Additional information
1 General
1.0.1 This method is formulated to uniformly test the compressive strength of ordinary concrete with a rebounder to ensure the detection accuracy.
1.0.2 This procedure is applicable to the detection of ordinary concrete compressive strength (hereinafter referred to as concrete strength) in engineering structures.
The inspection and assessment of concrete strength shall be carried out in accordance with the current national standards "Construction and Acceptance Specifications for Concrete Structure Engineering" and "Standards for Concrete Strength Inspection and Evaluation". When there is doubt about the strength of the concrete in the structure, it can be tested according to this procedure, and the test results can be used as a basis for the quality of the concrete.
This procedure does not apply to the detection of concrete members with significant differences in surface and internal quality or internal defects.
1.0.3 Any person who uses the rebound hammer for engineering inspection shall pass the professional training approved by the competent department and hold the corresponding qualification certificate.
1.0.4 Using the rebound method to detect and estimate the strength of concrete, in addition to complying with this regulation, it should also comply with the relevant national standards.
2 rebound
2.1 Technical requirements
2.1.1 For the instrument for determining the rebound value, the indicator system shall be used as a pointer-reading concrete rebound hammer. For rebound hammers of the same type of impact energy using other indication systems, the identification and approval, such as stable performance and reliable method of verifying the accuracy of the indication, are also allowed.
2.1.2 The hammer must have the product certificate of the manufacturing plant and the verification certificate of the verification unit.
2.1.3 A quality rebound hammer shall meet the requirements of the following standard conditions:
(1) At the moment of horizontal bounce, when the hammer is unhooked, the standard energy of the rebound hammer should be 2.2J;
(2) At the moment when the hammer and the impactor collide, the spring of the spring should be in a free state. At this time, the jump point of the hammer should correspond to the “0” on the scale indicated by the pointer;
(3) On a steel anvil with a Rockwell hardness HRC of 60 ± 2, the rate of the rebound hammer should be 80 ± 2.
2.1.4 The ambient temperature of the hammer should be between -4 °C and +40 °C.
2.2 Verification
2.2.1 The hammer should be sent to the verification unit for verification in one of the following cases:
(1) Before the new rebound hammer is activated;
(2) Exceeding the validity period of the verification (valid for half a year);
(3) The cumulative number of bombings exceeds 6,000 times;
(4) The steel anvil rate is not qualified after routine maintenance;
(5) Suffering from severe impact or other damage. 2.2.2 The rebound tester is located in a unit approved by the competent authority. The verification unit must verify the rebound hammer according to the metrological verification procedure.
2.2.3 The rebound hammer should be tested on the steel anvil before and after the engineering test.
2.2.4 The rebound test shall be carried out at room temperature of 20 ± 5 °C. At the timing, the anvil should be firmly placed on the concrete body with high rigidity. When the hammer rebounds downward, it takes an average rebound value of three consecutive shots to average, and the hitter should be rotated four times, each rotation by about 90°. The average value of the firing bar per rotation should meet the requirements of 80 ± 2.