The paper presents results of investigations of compressive strength and shrinkage of concrete samples made on the basis of the Portland cement CEM I 32.5R, after 2, 7, 14, 28, 90, and 365 days of maturation in four different maturation conditions. It was shown that after 28 days the samples cured according to the standard in the cuvettes with water achieved the highest compressive strength, although the early-age compressive strengths after 7 and 14 days were lower than those for the samples cured in building film and in dry conditions. A determined correlation between the compressive strength and shrinkage of the concrete proves that wet curing also allows a total elimination of the shrinkage in the first 28 days. Along with the growth of the compressive strength, the drying shrinkage reduces. Obtained results confirmed that the best way of concrete curing, among the analyzed methods, from the point of view of both compressive strength and volume changes is the wet curing.
Abstract. The paper presents the problem of estimating in-situ compressive strength of concrete in a comprehensive way, taking into account the possibility of direct tests of cored specimens and indirect methods of non-destructive tests: rebound hammer tests and ultrasonic pulse velocity measurements. The paper approaches the discussed problem in an original, scientifically documented and exhaustive way, in particular in terms of application.Key words: testing concrete in structures, cored specimens, non-destructive testing, basic curve, expression of uncertainty measurements, conformity criteria, characteristic in-situ compression strength. a normal distribution, the quantile of this distribution, equal to 0.05, was adopted as the characteristic strength f ck that determined the class of the concrete. At the same time, a requirement was established for the conformity criterion for the strength of a given concrete on the basis of testing of a series set of the individual n results of control specimens to be estimated for a confidence level γ of at least 0.50.
An approach to in-situ compressive strength of concreteThe approach to the problem requires both particularity of an adequate material model [3] of concrete composite and multicriterial optimization [8] methods of its assessment in situ.The conformity criteria are expressed in the form of mathematical inequalities of the following type:
BULLETIN OF THE POLISH ACADEMY OF SCIENCES TECHNICAL SCIENCES, VOL. XX, NO. Y, 2016Approach of concrete compressive strength in situ Brunarski L. 1 , Dohojda M. Abstract: The paper presents the problem of estimation of concrete compressive strength in-situ in a comprehensive way, taking into account the possibility of direct tests of cored specimens and indirect methods of non-destructive tests: rebound hammer tests and ultrasonic pulse velocity measurements. The paper approaches the discussed problem in an original, scientifically documented and exhaustive way, in particular in terms of application.
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