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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 91 Abstracts search results
Document:
SP128-03
Date:
November 1, 1991
Author(s):
K. W. Nasser and P. S. H. Lai
Publication:
Symposium Papers
Volume:
128
Abstract:
This paper describes an investigation that was carried out to determine the within-test variability of various nondestructive test methods and their correlation with the corresponding compressive strength. The nondestructive test methods that were studied were the pin penetration, the ultrasonic pulse velocity, and the nuclear density gage. The tests were performed on solid concrete blocks, cylinders, and reinforced concrete slabs at different ages. The within-test variability of the direct readings of the ultrasonic pulse velocity was small compared to the pin penetration and nuclear density gage. However, when the readings were translated into strength, the within-test variabilities of the standard compression test were about the same as the other methods. The relationship between strength and the pin penetration and pulse velocity readings were good, while the relationship between the density of fresh and hardened concrete and the nuclear gage readings were satisfactory.
DOI:
10.14359/3627
SP128-07
Hemant S. Limaye and Donald F. Meinheit
Over the last 3 years, an impact-echo technique has proven to be an effective evaluation tool in identifying defects and locating embedded items in concrete structures. The advantages of the method are that it is nondestructive, relatively easy to calibrate, and testing can be conducted from one surface of the element under test. Operating experience with the impact-echo technique has shown that, within known limitations, the technique can provide a rapid nondestructive means for performing certain concrete condition surveys.
10.14359/3636
SP128-09
M. Sansalone, Y. Lin, D. Pratt, and C. C. Cheng
This paper summarizes recent developments in the impact-echo technique for locating defects in concrete structures. First, the impact-echo principle is reviewed and frequency analysis of impact-echo signals is explained for those unfamiliar with the technique. Advancements in signal processing that have been aimed at simplifying and automating data interpretation are discussed, and examples from the use of an artificial-intelligence technique for automated interpretation of signals from plate-like structures are shown. Impact-echo instrumentation is reviewed and an impact-echo field system is described. The newest application for the method is testing bar-like structures, such as columns and beams. Numerical and experimental controlled-flaw studies established the basis for the use of impact-echo for this application. Representative results obtained from impact-echo studies carried out on reinforced concrete columns with circular and rectangular cross sections are presented. Finally, an overview of ongoing research is presented.
10.14359/3639
SP128-04
N. A. Cumming, P. T. Seabrook, and V. Malhotra
A research program was undertaken to evaluate commercially available nondestructive testing techniques to locate voids in grouted tendon ducts. A laboratory scale mockup was used to evaluate several methods. On the basis of these results, impact-echo, ultrasonic, pulse-echo, and ultrasonic pitch-catch systems were selected for further evaluation. A full-scale mockup of a section representing an icewall of an offshore drilling structure was fabricated. It contained grouted tendon ducts with voids of various sizes and configuration. A test was carried out in which three teams of researchers from Canada and the U.S. evaluated nondestructively the mockup without knowledge of the locations or nature of the voids. This paper presents the results of the preceding evaluation and makes recommendations for further research.
10.14359/3648
SP128-06
C. T. Tam
The use of nondestructive testing in the laboratory is well-documented and standard specifications are available. However, when these nondestructive testing methods are used on site, additional factors have to be taken into consideration to enable meaningful interpretation of measurements obtained. This aspect of knowledge has not received sufficient attention for standard specifications to be drafted. Suggestions are put forward in this paper on precautions to be taken when applying nondestructive testing on site. The methods of testing discussed include the magnetic method of concrete cover or bar size determination, the rebound hardness, ultrasonic pulse velocity and the penetration resistance (Windsor Probe) test. The methods of calibration in the laboratory are reviewed and the ways to check on equipment and its calibration during site work are proposed. The information to be recorded and the interpretation of data are discussed. The need for trained personnel to carry out site testing, as well as experienced professionals to interpret test results, is emphasized.
10.14359/3666
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