Issue 50

S. Gavela et alii, Frattura ed Integrità Strutturale, 50 (2019) 383-394; DOI: 10.3221/IGF-ESIS.50.32 383 Focused on the research activities of the Greek Society of Experimental Mechanics of Materials Experimental uncertainty budget for concrete compressive strength test based on a multifactorial analysis Stamatia Gavela, Nikolaos Nikoloutsopoulos, George Papadakos, Dimitra Passa, Anastasia Sotiropoulou School of Pedagogical and Technological Education, Department of Civil Engineering Educators matina@gavela.gr , http://orcid.org/0000-0003-0775-2750 ; nikolasnikoloutso@hotmail.com ; gpapadakos@teemail.gr; dimpassa@aspete.gr; sotiropoulou@aspete.gr A BSTRACT . The objective of the study is to introduce an experimental uncer- tainty budget process for concrete compressive strength test, based on a proto- col that incorporates effects of multiple factors significant for the measure- ment result. The proposed procedure is rather useful for laboratories seeking accreditation according to ISO/IEC 17025, in order to emphasize the contribu- tion of type A uncertainty estimations, rather than relying on type B estimations that are unable to address the correlation between those factors. Two indepen- dent experiments were performed. Experiment I is proposed as a simple, suit- ably designed, reproducibility trial for laboratories performing EN 12390 test method, i.e. when a specified nominal curing age is targeted, following experi- mental design on multiple uncertainty parameters. A sensitivity analysis was introduced based on a semi-empirical multifactorial regression model (experi- ment II) for concrete compressive strength as a function of specimen’s curing age and W/C ratio. The present study is an effort towards an integrated and standardized method for experimental, semi-empirical multifactorial regression estimation of the uncertainty budget for the EN 12390 test method, being useful, also, as a baseline for internal quality control programs when adjusted for the specific characteristics of concrete specimens tested by a laboratory. K EYWORDS . Concrete compressive strength test; Multifactorial model; Type A uncertainty estimation; Sensitivity analysis. Citation: Gavela, S., Nikoloutsopoulos, N., Papadakos, G., Passa, D., Sotiropoulou, A. Experimental uncertainty budget for concrete compressive strength test based on a multi- factorial analysis, Frattura ed Integrità Struttu- rale, 50 (2019) 383-394. Received: 19.01.2019 Accepted: 14.05.2019 Published: 01.10.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION etermination of the uncertainty budget in cases of measuring the compressive strength of concrete specimens is critical as it is a quantitative criterion according to which the result of a corresponding test is assessed against the compliance of the specimen with concrete specifications. This is particularly emphasized in the new version of International Standard ISO/IEC 17025:2017, by which it is required that any conformity assessment laboratory output D