Experimental uncertainty budget for concrete compressive strength test based on a multifactorial analysis

Abstract

The objective of the study is to introduce an experimental un­cer­tainty budget process for concrete compressive strength test, based on a pro­to­col that incorporates effects of multiple factors significant for the measure­ment result. The proposed procedure is rather useful for laboratories seeking accreditation according to ISO/IEC 17025, in order to emphasize the contri­bu­tion of type A uncertainty estimations, rather than relying on type B estimations that are unable to address the correlation between those factors. Two indepen­dent experiments were performed. Experiment I is proposed as a simple, suit­ably designed, reproducibility trial for laboratories performing EN 12390 test method, i.e. when a specified nominal curing age is targeted, following experi­mental design on multiple uncertainty parameters. A sensitivity analysis was introduced based on a semi-empirical multifactorial regression model (experi­ment 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.