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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 40 Abstracts search results
Document:
SP82
Date:
September 1, 1984
Author(s):
Editor: V.M. Malhotra
Publication:
Symposium Papers
Volume:
82
Abstract:
SP82 Contains 38 papers covering the following in situ/nondestructive testing methods: surface hardness and penetration resistance tests; pullout; ultrasonic pulse velocity; break-off; combined methods; maturity techniques. For tests of concrete other than strength: magnetic; electrical; radioactive; pulse echo; radar; microwave absorption; acoustic emission; nuclear; infrared thermography; and permeability methods. A global review of in situ/nondestructive testing is also included.
DOI:
10.14359/14039
SP82-09
W.L. Vogt, V. Beizai, and R.L. Dilly
A review of available literature indicates that the "finger placing" technique of embedding pullout inserts in concrete after placement has not been used for determining an the in-situ concrete strength development durin construction. Early strength information may be a useful guide line for form removal, stressing or reshoring. This technique o embedding pullout inserts to determine the strength of hardene concrete was used during the construction of a box Culver requiring approximately 11,500 m3 of concrete. Thirty location on the structure were tested to determine the force required t extract embedded inserts at ages of two, four, and seven days higher pullout forces were required to extract insert as the concrete matured. Currently no criteria exist for eval uating the pullout test results; however, the data obtaine throughout this study appear to be normally distributed at earl The standard deviation and within test variation values ar higher than expected. Improvements in these parameters may b achieved by improvements in finger placing and testing techniques
10.14359/6554
SP82-10
Thomas J. Parsons and Tarun R. Naik
This paper reports results of an investigation of the use of pullout testing and the maturity method to predict the early age strength of concrete. Concrete specimens, composed of 12 variations of 2 cement types, 2 aggregate types, and 3 water-cement cured at different temperatures: 37OF (2.8°C), and the outdoor environ-Cylinder compression and pullout tests were performed on specimens at ages ranging from 12 to 168 hours (7 days). Regression equations for cylinder strength and maturity, and pullout force and maturity are developed where the maturity is modified by changing the datum temperature from -10° C to 0° C to improve the predictive capabilities. A model for the prediction of the cylinder strength in terms of maturity is developed, as well as a oncrete strength by the pullout ombining cylinder strength and The reliability of the pullout model was affected by the comparative rates of strength gain of the cylindrical specimens and the slab specimens.
10.14359/6555
SP82-11
V.R. Sturrup, F.J. Vecchio, and H. Caratin
Pulse Velocity/Strength relationships can be estab-lished for concrete but they are influenced by many factors. Of particular significance are the proportions and composition of the components, age s curing conditions and moisture content of the concrete. Cement type, air-entrainment and curing temperatures -influence to a lesser degree. Pulse velocity correlates well with strength at early ages but is insensitive to even major increases in strength at later ages. A relationship established at early ages therefore is not applicable as the concrete matures. A rela-tionship determined on sound concrete during its development stage cannot be used to predict the strength of concrete that is deteriorating. Such a relationship should be established on cores from the concrete in question. A relationship established using laboratory-cured specimens, cannot be used with assurance to follow strength development in a structure. A Pulse Velocity Strength relationship can be confused by cracks, voids or other discontinuities in the concrete.
10.14359/6556
SP82-12
J.H. Bungey
Embedded reinforcement may have a significant effect on ultrasonic pulse velocity measurements taken through structural concrete members. Reliable corrections are essential if test locations cannot avoid the influence of the steel. Extensive laboratory experimental work demonstrates major shortcomings in all currently accepted allowance procedures and confirms that bar diameter is an essential variable to be incorporated. The effect of bars passing across the pulse path is shown to be less than for bars of similar size running along the path. A correction procedure is proposed which can meet many practical combinations of bar size, bar orientation and concrete properties with significantly greater accuracy than possible by established methods.
10.14359/6557
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