ISO 1920-7-2004 Testing of concrete - Part 7 Non-destructive tests on hardened concrete《混凝土试验 第7部分 硬化混凝土的无损试验》.pdf

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1、 Reference number ISO 1920-7:2004(E) ISO 2004INTERNATIONAL STANDARD ISO 1920-7 First edition 2004-08-01 Testing of concrete Part 7: Non-destructive tests on hardened concrete Essais du bton Partie 7: Essais non destructifs du bton durci ISO 1920-7:2004(E) PDF disclaimer This PDF file may contain emb

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4、 were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2004 All rights reserved. Unless otherwise spe

5、cified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office

6、Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2004 All rights reservedISO 1920-7:2004(E) ISO 2004 All rights reserved iiiContents Page Foreword iv 1 Scope 1 2 Terms and definitions. 1 3 Determina

7、tion of rebound number 2 3.1 Principle . 2 3.2 Apparatus. 2 3.3 Test area. 2 3.4 Procedure. 3 3.5 Test results 3 3.6 Test report 4 4 Determination of ultrasonic pulse velocity 4 4.1 Principle . 4 4.2 Apparatus. 4 4.3 Performance requirements of apparatus 5 4.4 Procedure. 5 4.5 Expression of results

8、6 4.6 Test report 6 5 Determination of pull-out force . 6 5.1 Principle . 6 5.2 Apparatus. 6 5.3 Test area. 7 5.4 Procedure. 9 5.5 Expression of results 9 5.6 Test report 9 6 General requirements for test reports 9 Annex A (informative) Method of obtaining a correlation between strength and rebound

9、number 11 Annex B (informative) Factors influencing the rebound of a concrete surface. 12 Annex C (informative) Example of a test report of the rebound number of hardened concrete 14 Annex D (normative) Determination of pulse velocity Indirect transmission . 15 Annex E (informative) Factors influenc

10、ing pulse velocity measurements. 16 Annex F (informative) Correlation of pulse velocity and strength 19 Annex G (informative) Example of a test report of the ultrasound pulse velocity of hardened concrete . 21 Annex H (informative) Relationship between pull-out force and strength of concrete. 22 Ann

11、ex I (informative) Example of a test report of the pull-out force of hardened concrete . 23 Bibliography . 24 ISO 1920-7:2004(E) iv ISO 2004 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies)

12、. The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non

13、-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part

14、 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting

15、a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 1920-7 was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and p

16、re- stressed concrete, Subcommittee SC 1, Test methods for concrete. ISO 1920 consists of the following parts under the general title Testing of concrete: Part 1: Sampling of fresh concrete Part 2: Properties of fresh concrete Part 3: Making and curing test specimens Part 4: Strength of hardened con

17、crete Part 5: Properties of hardened concrete other than strength Part 6: Sampling, preparing and testing concrete cores Part 7: Non-destructive tests on hardened concrete INTERNATIONAL STANDARD ISO 1920-7:2004(E) ISO 2004 All rights reserved 1Testing of concrete Part 7: Non-destructive tests on har

18、dened concrete 1 Scope This part of ISO 1920 specifies non-destructive test methods for use on hardened concrete. The methods included are a) determination of rebound number, b) determination of ultrasonic pulse velocity, and c) determination of pull-out force. NOTE These test methods are not intend

19、ed to be an alternative for the determination of compressive strength of concrete, but with suitable correlations they can provide an estimate of in-situ strength. 2 Terms and definitions For the purpose of this document, the following terms and definitions apply. NOTE Additional terms are defined i

20、n other parts of ISO 1920. 2.1 rebound number rebound number test reading on a rebound hammer, which is related to the proportion of the energy returned to the hammer after striking the surface of the concrete 2.2 test area rebound number test region of concrete that is being assessed and which, for

21、 practical purposes, is assumed to be of uniform quality 2.3 median rebound number test middle value of a set of numbers when arranged in size order NOTE If the set has an even number of items, the median is taken as the mean of the middle two. 2.4 transit time ultrasonic pulse velocity test time ta

22、ken for an ultrasonic pulse to travel from the transmitting transducer to the receiving transducer, passing through the interposed concrete 2.5 onset ultrasonic pulse velocity test leading edge of the pulse detected by the measuring apparatus ISO 1920-7:2004(E) 2 ISO 2004 All rights reserved2.6 rise

23、 time ultrasonic pulse velocity test time for the leading edge of the first pulse to rise from 10 % to 90 % of its maximum amplitude 3 Determination of rebound number 3.1 Principle A mass propelled by a spring strikes a plunger in contact with the surface. The test result is expressed in terms of th

24、e rebound distance of the mass. NOTE Annex A describes a method of obtaining a correlation between strength and rebound number. 3.2 Apparatus 3.2.1 Rebound hammer, hammer comprising a spring-loaded steel hammer that, when released, strikes a steel plunger in contact with the concrete surface. The sp

25、ring-loaded hammer shall travel with a fixed and repeatable velocity. The rebound distance of the steel hammer from the steel plunger shall be measured on a linear scale attached to the frame of the instrument. The rebound hammer shall be calibrated twice a year to validate the calibration curve. It

26、 shall also be calibrated whenever there is a reason to question its proper operation. NOTE Several types and sizes of rebound hammers are commercially available for testing various strengths and types of concrete. Each type and size of hammer should be used only with the strength and type of concre

27、te for which it is intended. For testing concretes with a low surface hardness, such as lightweight concrete, a pendulum-type rebound hammer of low impact energy is suitable. 3.2.2 Steel reference anvil, for verification of the hammer, defined with a hardness of minimum 52 HRC and a mass of 16 kg 1

28、kg and a diameter of approximately 150 mm, except where the annex in a national standard defines a different mass. NOTE Verification on an anvil will not guarantee that different hammers will yield the same results at other points on the rebound scale. 3.2.3 Abrasive stone, medium-grain texture sili

29、con carbide stone or equivalent material. 3.3 Test area 3.3.1 Selection If the concrete elements to be tested are not at least 100 mm thick and fixed within a structure, they shall be rigidly supported during testing. Areas exhibiting honeycombing, scaling, rough texture, or high porosity should be

30、avoided. In selecting an area to be tested, the factors described in Annex B should be taken into account. A test area shall be approximately 300 mm 300 mm. NOTE It is normally better to confine the readings to a limited test area, rather than take random readings over the whole structure or element

31、. ISO 1920-7:2004(E) ISO 2004 All rights reserved 33.3.2 Preparation Heavily textured or soft surfaces and surfaces with loose mortar shall be ground smooth using the abrasive stone (3.2.3). Smooth-formed or trowelled surfaces may be tested without grinding. Remove any water present on the surface o

32、f the concrete. 3.4 Procedure 3.4.1 Preliminaries Use the rebound hammer (3.2.1) in accordance with the manufacturers instructions for its operation. Activate it at least three times before taking any readings, to ensure that it is working correctly. Before a sequence of tests on a concrete surface,

33、 take and record readings using the steel reference anvil (3.2.2) and ensure that they are within the range recommended by the manufacturer. If they are not, then clean and/or adjust the hammer. The hammer should normally be operated at a temperature within the range of 10 C to 35 C. 3.4.2 Determina

34、tion Hold the hammer firmly in a position that allows the plunger to impact perpendicularly to the surface being tested. Gradually increase the pressure on the plunger until the hammer impacts. After impact, record the rebound number. NOTE There are hammers with automatic writing equipment and, in t

35、hese cases, the rebound number is recorded automatically. Use a minimum of nine readings to obtain a reliable estimate of the rebound number for a test area. Record the position and orientation of the hammer for each set of readings. No two impact points shall be closer together than 25 mm and none

36、shall be within 50 mm from an edge. NOTE It is preferable to draw a regular grid of lines 25 mm to 50 mm apart and take the intersections of the lines as the test points. Examine each impression made on the surface after impact. If the impact has crushed or broken through a near-to-surface void, the

37、 result shall be discounted. 3.4.3 Reference checking After testing the concrete, take readings using the steel anvil (3.2.2). Record and compare these with those taken prior to the test (see 3.4.1). If the results differ, clean and/or adjust the hammer and repeat the test. 3.5 Test results The resu

38、lt for the test area shall be taken as the mean of all the readings, adjusted if necessary to take into account the orientation of the hammer in accordance with the manufacturers instructions, and expressed as a whole number. If more than one hammer is to be used, a sufficient number of tests should

39、 be made on similar concrete surfaces so as to determine the magnitude of the differences to be expected. NOTE 1 A method for obtaining a correlation between strength and rebound number is given in Annex A. NOTE 2 For factors influencing the rebound number, see Annex B. If more than 20 % of all the

40、readings differ from the mean value by more than 6 units, the entire set of readings shall be discarded. ISO 1920-7:2004(E) 4 ISO 2004 All rights reserved3.6 Test report An example of a test report is given in Annex C. In addition to the details required by Clause 6, the report shall include the fol

41、lowing: a) identification of the rebound hammer; b) reference anvil readings, before and after tests; c) test result (mean value) and hammer orientation for each test area; d) individual rebound hammer readings (when specified); e) test result adjusted for hammer orientation (if appropriate). 4 Dete

42、rmination of ultrasonic pulse velocity 4.1 Principle A pulse of longitudinal vibrations is produced by an electro-acoustical transducer held in contact with one surface of the concrete under test. After traversing a known path length in the concrete, the pulse of vibrations is converted into an elec

43、trical signal by a second transducer and electronic timing circuits enable the transit time of the pulse to be measured. 4.2 Apparatus The apparatus comprises the following. 4.2.1 Electrical pulse generator The pulse velocity of the apparatus should be calibrated against a standard calibration bar,

44、generally supplied by the manufacturer of the apparatus. 4.2.2 Pair of transducers The natural frequency of the transducers should normally be within the range 20 kHz to 150 kHz. NOTE Frequencies as low as 10 kHz and as high as 200 kHz can sometimes be used. High-frequency pulses have a well-defined

45、 onset but, as they pass through the concrete, they become attenuated more rapidly than pulses of lower frequency. It is therefore preferable to use high-frequency transducers (60 kHz to 200 kHz) for short path lengths (down to 50 mm) and low frequency transducers (10 kHz to 40 kHz) for long path le

46、ngths (up to a maximum of 15 m). Transducers with a frequency of 40 kHz to 60 kHz are found to be useful for most applications. 4.2.3 Amplifier 4.2.4 Electronic timing device, for measuring the time interval elapsing between the onset of a pulse generated at the transmitting transducer and the onset

47、 of its arrival at the receiving transducer. Two forms of the electronic timing apparatus are available: an oscilloscope on which the first front of the pulse is displayed in relation to a suitable time scale; an interval timer with a direct reading digital display. NOTE An oscilloscope provides the

48、 facility for examining the wave form, which can be advantageous in complex situations. ISO 1920-7:2004(E) ISO 2004 All rights reserved 54.2.5 Apparatus for determination of arrival time of the pulse The apparatus shall be capable of determining, in microseconds, the time of arrival of the first fro

49、nt of the pulse, even though this may be of small amplitude compared with that of the first half wave of the pulse. 4.3 Performance requirements of apparatus The apparatus shall conform to the following performance requirements: a) it shall be capable of measuring transit times in the calibration bar to an accuracy of 0,1 s; b) the electronic excitation pulse applied to the transmitting transducer shall have a rise time of not greater than one-quarter of its natural period; this is to ensure a sharp pul