Handbook of nondestructive testing of concrete:Penetration Resistance Methods.pdf
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1、2-1 2 Penetration Resistance Methods* 2.1Introduction 2-1 2.2Probe Penetration Test System. 2-2 Principle Description Method of Testing Correlation Pocedure 2.3Evaluation of the Probe Penetration Test 2-4 Mechanism of Concrete Failure Correlations between Probe Test Results and Compressive Strength
2、Variability of the Probe Penetration Test Variations in the Estimated Strength Values Nondestructive Nature of the Probe Penetration Test Use of the Probe Penetration Test for Early Form Removal Probe Penetration Test vs. Core Testing Probe Penetration Test vs. Rebound Hammer Test North American Sur
3、vey on the Use of the Probe Penetration Test Advantages and Disadvantages of the Probe Penetration Test 2.4Pin Penetration Test 2-13 2.5Standardization of Penetration Resistance Techniques 2-15 2.6Limitations and Usefulness of Penetration Resistance Methods. 2-15 This chapter reviews the development
4、 of penetration resistance methods for testing concrete nondestruc- tively. These are being increasingly used for quality control and strength estimation of in situ concrete. Among the penetration techniques presently available, the most well known and widely used is the Windsor probe test. The prin
5、ciple of this method, the test equipment and procedures, and the preparation of calibration charts are described in detail. Factors affecting the variability of the test are discussed. Correla- tions that have been developed between the Windsor probe test results and the compressive strength of conc
6、rete are presented. A pin penetration test was developed in Canada for the purpose of determining safe form removal times. The advantages, limitations, and applications of the penetration methods are outlined. The chapter concludes with a list of pertinent references. 2.1Introduction Penetration res
7、istance methods are based on the determination of the depth of penetration of probes (steel rods or pins) into concrete. This provides a measure of the hardness or penetration resistance of the material that can be related to its strength. *Minister of Supply and Services Canada, 1989. *Deceased. V.
8、 Mohan Malhotra Department of Natural Resources Canada, Ottawa Georges G. Carette* Department of Natural Resources Canada, Ottawa 2-2Handbook on Nondestructive Testing of Concrete: Second Edition The measurement of concrete hardness by probing techniques was reported by Voellmy1 in 1954. Two techniq
9、ues were used. In one case, a hammer known as Simbi was used to perforate concrete, and the depth of the borehole was correlated to the compressive strength of concrete cubes. In the other technique, the probing of concrete was achieved by Spit pins, and the depth of penetration of the pins was corr
10、elated with the compressive strength of concrete Apart from the data reported by Voellmy, there is little other published work available on these tests, and they appear to have received little acceptance in Europe or elsewhere. Perhaps the introduction of the rebound method around 1950 was one of th
11、e reasons for the failure of the above tests to achieve general acceptance. In the 1960s, the Windsor probe test system was introduced in the United States and this was followed by the pin penetration test in Canada in the 1980s. 2.2Probe Penetration Test System Between 1964 and 1966. a device known
12、 as the Windsor probe was advanced for penetration testing of concrete in the laboratory as well as in situ. The device was meant to estimate the quality and compressive strength of in situ concrete by measuring the depth of penetration of probes driven into the concrete by means of a powder-actuate
13、d driver. The development of this technique was the joint undertaking of the Port of New York Authority, New York, and the Windsor Machinery Co., Connecticut. This development was closely related to studies reported by Kopf.2 Results of the investigations carried out by the Port of New York Authorit
14、y were presented by Cantor3 in 1970. Meanwhile, a number of other organizations had initiated exploratory studies of this technique,48 and a few years later, Arni9,10 reported the results of a detailed investigation on the evaluation of the Windsor probe, while Malhotra1113 reported the results of h
15、is investigations on both 150 300-mm cylinders and 610 610 200-mm concrete slabs. In 1972, Klotz14 stated that extensive application of the Windsor probe test system had been made in investigations of in-place compressive strength of concrete and in determinations of concrete quality. The Windsor pr
16、obe had been used to test reinforced concrete pipes, highway bridge piers, abutments, pavements, and concrete damaged by fi re. In the 1970s, several U.S. federal agencies and state highway departments reported investigations on the assessment of the Windsor probe for in situ testing of hardened con
17、crete.1519 In 1984 Swamy and Al-Hamed20 in the U.K. published results of a study on the use of the Windsor probe system to estimate the in situ strength of both lightweight and normal weight concretes. 2.2.1Principle The Windsor probe, like the rebound hammer, is a hardness tester, and its inventors
18、 claim that the penetration of the probe refl ects the precise compressive strength in a localized area is not strictly true.21 However, the probe penetration relates to some property of the concrete below the surface, and, within limits, it has been possible to develop empirical correlations betwee
19、n strength properties and the pene- tration of the probe. 2.2.2Description The Windsor probe consists of a powder-actuated gun or driver (Figure 2.1), hardened alloy-steel probes, loaded cartridges, a depth gauge for measuring the penetration of probes, and other related equipment. The probes have a
20、 tip diameter of 6.3 mm, a length of 79.5 mm, and a conical point (Figure 2.2). Probes of 7.9 mm diameter are also available for the testing of concretes made with lightweight aggregates. The rear of the probe is threaded and screws into a probe-driving head, which is 12.7 mm in diameter and fi ts s
21、nugly into the bore of the driver. The probe is driven into the concrete by the fi ring of a precision powder charge that develops an energy of 79.5 m-kg. For the testing of relatively low-strength concrete, the powder level can be reduced by pushing the driver head further into the barrel. Penetrat
22、ion Resistance Methods2-3 2.2.3Method of Testing The method of testing is relatively simple and is given in the manual supplied by the manufacturer. The area to be tested must have a brush fi nish or a smooth surface. To test structures with coarse fi nishes, the surface fi rst must be ground smooth
23、 in the area of the test. Briefl y, the powder-actuated driver is used to drive a probe into concrete. If fl at surfaces are to be tested, a suitable locating template to provide 178-mm equilateral triangular pattern is used, and three probes are driven into the concrete, one at each corner. The exp
24、osed lengths of the individual probes are measured by a depth gauge. The manufacturer also supplies a mechanical averaging device for measuring the average exposed length of the three probes fi red in a triangular pattern. The mechanical averaging device consists of two triangular plates. The refere
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