摘要:

The sound velocity measurement of longitudinal waves is of interest for nondestructively evaluating concrete structures because the velocity is closely related to the elastic properties of concrete and the standards of the method for measuring sound velocity in concrete have already been established in several countries. The descriptions of the measuring method are certainly correct, however, it may be difficult to obtain the same results from different instruments in practice not only because of the positioning method of the transmission and reception pulses but also materials, geometric forms and dimensions of the reference blocks for the instrument calibration are different for each kind of instrument. In order to obtain the same results from different instrument, it will be very significant to use a specified reference test block for calibrating each instrument. In accordance with these considerations, the reference block made with a core block of acrylic resin separating aluminium alloy plates was developed, which has the acoustical characteristics )acoustic impedance of test surface and sound velocity of longitudinal wave( nearly comparable to that of concrete. The effect of this reference block in actual measurement of the sound velocity in concrete was assessed for the drafting committee of JSNDI )Japanese Society for Non-Destructive Inspection(.

ISSN:1058-9759    

DOI:10.1080/10589759508952832

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

It has been shown that one of the most important factors affecting a radar survey of a concrete structure is the operational frequency of the antenna. The operational choice of frequency is difficult as there is always a compromise between signal penetration and resolution. Whilst case histories have proved valuable sources of information, they have not yielded the systematic data needed by structural engineers specifying investigative studies.

ISSN:1058-9759    

DOI:10.1080/10589759508952833

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Sub-surface impulse radar has recently become an established technique for detecting a wide range of buried features in concrete. The background and scope of this technique are outlined in this paper, together with relevant findings of a recent major 5. E. R. C. funded project undertaken at Liverpool University. Location and identification of buried steel reinforcing bars and voids represent two important applications which are considered, with particular attention concentrated upon voids. A wide range of experimental results have been obtained for various configurations of size, shape and depth and are supported by numerical modelling. The ability of a I GHz system to detect air and water filled voids is discussed in detail, and practical guidance is offered to assist the execution and interpretation of such investigations.

ISSN:1058-9759    

DOI:10.1080/10589759508952834

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper descirbes a simple test measuring the sorptivity (a measure of the absorption property if concrete) and the air and water permeability of concrete on site. Using this test, the decay of pressure is monitired for the air permeability test.whereas water penetrating into the concrete at a constant pressure of 0.01 bar and 1.5 bar are recorded for the sorptivity and the water permeability tests respectively. These tests are essentially non-destructive in nature and a skilled operator is not needed. It is possible to carry out a number of tests quickly and efficiently on site without prior planning. It has been found that statistically satisfactory results can be obtained from a mean of three tests. As the flow lines are largely concentrated within 40 mm from the surface, reasonably reliable results can be obtained by drying the surface even if the surface under test is initially wet.

ISSN:1058-9759    

DOI:10.1080/10589759508952835

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The need for the development of non-destructive methods for evaluating structural brickwork is outlined and different approaches to the application of NDE are reviewed. An approach based on the separate evaluation of the bricks themselves, the mortar and the most important variable in practice, the workmanship, is advocated. Anevaluation method usingchanges in ultrasonic pulse transit timeasa measure of variations in quality is developed based on a range of test data. The approach is shown to be capable of detecting potential construction errors, such as the use of under strength mortar or the incomplete filling of the mortar joints.

ISSN:1058-9759    

DOI:10.1080/10589759508952836

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor