Abstract
The aim of this preliminary survey is to provide a literature review in order to investigate the connection between compressive strength measured in core samples and the design strength of concrete, and to identify the central factors involved in testing the strength of concrete. Source material for the preliminary survey includes Finnish and international standards and previous research results.
The first section of the report summarises factors related to concrete strength and its measurement, and reviews a selection of previous studies on the matter. The report describes national guidelines and practices on measuring the strength of core samples from Finland, Sweden, Germany, the UK and the US. In the case of Finland, the report also describes the procedure for demonstrating conformance using standard-cured test samples, and an example calculation on determining the design strength of concrete on the basis of test results from core samples. The final section of the report presents the conclusions of the preliminary survey and further research needs.
Based on the literature review, four areas were identified that affect the design value of concrete calculated from core sample tests:
• Use of correction factors to account for differences in core and standard-cured test samples
• Statistical methods used to determine the characteristic strength of concrete in core samples
• Accounting for the differences in strength in standard-cured test samples and core samples
• The material-specific partial safety factor used to determine the design strength of concrete
The preliminary survey found that the measured strength of core samples is affected by a large number of factors, such as the size and moisture condition of the sample. There are differences between countries in accounting for the various factors, and studies on the topic reached differing conclusions. The uncertainty of strength measurements from core samples can be reduced by standardising as many of the related factors as possible, and by correcting them as close to the corresponding values of standard-cured samples as possible. If non-standard procedures are used, their effects on the measured strength of samples should be understood as accurately as possible.
The first section of the report summarises factors related to concrete strength and its measurement, and reviews a selection of previous studies on the matter. The report describes national guidelines and practices on measuring the strength of core samples from Finland, Sweden, Germany, the UK and the US. In the case of Finland, the report also describes the procedure for demonstrating conformance using standard-cured test samples, and an example calculation on determining the design strength of concrete on the basis of test results from core samples. The final section of the report presents the conclusions of the preliminary survey and further research needs.
Based on the literature review, four areas were identified that affect the design value of concrete calculated from core sample tests:
• Use of correction factors to account for differences in core and standard-cured test samples
• Statistical methods used to determine the characteristic strength of concrete in core samples
• Accounting for the differences in strength in standard-cured test samples and core samples
• The material-specific partial safety factor used to determine the design strength of concrete
The preliminary survey found that the measured strength of core samples is affected by a large number of factors, such as the size and moisture condition of the sample. There are differences between countries in accounting for the various factors, and studies on the topic reached differing conclusions. The uncertainty of strength measurements from core samples can be reduced by standardising as many of the related factors as possible, and by correcting them as close to the corresponding values of standard-cured samples as possible. If non-standard procedures are used, their effects on the measured strength of samples should be understood as accurately as possible.
| Translated title of the contribution | Compressive strength of concrete: Preliminary survey: Background and estimation from test results |
|---|---|
| Original language | Finnish |
| Publisher | Liikennevirasto |
| Number of pages | 71 |
| Volume | 32 |
| Edition | 2018 |
| ISBN (Electronic) | 978-952-317-555-6 |
| Publication status | Published - 3 May 2018 |
| Publication type | D4 Published development or research report or study |
Publication series
| Name | Liikenneviraston tutkimuksia ja selvityksiä |
|---|---|
| Publisher | Liikennevirasto |
| ISSN (Print) | 1798-6664 |