DBPapers
DOI: 10.5593/SGEM2014/B62/S26.006

APPLICATION OF DIFFERENT STANDARD METHODS WHEN CONTROLLING THE STRENGTH OF CONCRETE IN STRUCTURE

A. Sicakova, L. Kyjakova
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-21-6 / ISSN 1314-2704, June 19-25, 2014, Book 6, Vol. 2, 41-48 pp

ABSTRACT
When assessing strength of concrete in finished structure and determining the strength class, two standard methods may be used in Europe, while the result may not be the same. For evaluation of concrete in the structures ISO 13822 is used, which states general procedure how to determine characteristic properties of all types of materials. Characteristic value of property (strength) is determined based on calculation using variable coefficient Vx and coefficient for determining 5% fractile. The second method is given by EN 13791, where the value of characteristic strength is determined based either on standard deviation, or average value depending on number of samples. The article covers an example of evaluation of concrete strength in structure by both methods, using samples taken from the real structure and aged for 14 days and 1 year. Differences in concrete strength that may occur due to the method used and testing time are pointed out. Results show that evaluation according to ISO standard is greatly influenced by diffusion of the results within the set of samples, as well as specification of strength classes being rather strict, thus evaluated concrete get assigned lower strength class. Difference in evaluation of the samples after 1 year shows as much as 3 classes.

Keywords: sustainability, durability of concrete, strength of concrete, strength class