Non-destructive assessment of both mean strength and variability of concrete: A new bi-objective approach

Alwash, Maitham; Sbartaï, Zoubir Mehdi; Breysse, Denys

doi:10.1016/j.conbuildmat.2016.03.120

Cited by 47 publications

(16 citation statements)

References 13 publications

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“…Thus, they have been used to estimate concrete compressive strength since 1960 [4,5]. Recently, research on a new estimating equation for NDTs has been carried out [6][7][8]. For NDT methods, it was reported that the rebound or ultrasonic velocity could be substantially impacted by void condition, age and the humidity of the concrete [9].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Compressive Strength of High Strength Concrete Using Non-Destructive Technique and Concrete Core Strength

Park

2017

Applied Sciences

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Abstract:Estimating the compressive strength of high strength concrete (HSC) is an essential investigation for the maintenance of nuclear power plant (NPP) structures. This study intends to evaluate the compressive strength of HSC using two approaches: non-destructive tests and concrete core strength. For non-destructive tests, samples of HSC were mixed to a specified design strength of 40, 60 and 100 MPa. Based on a dual regression relation between ultrasonic pulse velocity (UPV) and rebound hammer (RH) measurements, an estimation expression is developed. In comparison to previously published estimation equations, the equation proposed in this study shows the highest accuracy and the lowest root mean square error (RMSE). For the estimation of compressive strength using concrete core specimens, three different concrete core diameters were examined: 30, 50, and 100 mm. Based on 61 measured compressive strengths of core specimens, a simple strength correction factor is investigated. The compressive strength of a concrete core specimen decreases as the core diameter reduces. Such a relation is associated with the internal damage of concrete cores and the degree of coarse aggregate within the core diameter from the extracting process of the cores. The strength estimation expressions was formulated using the non-destructive technique and the core strength estimation can be updated with further test results and utilized for the maintenance of NPP.

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Section: Introductionmentioning

confidence: 99%

Estimation of Compressive Strength of High Strength Concrete Using Non-Destructive Technique and Concrete Core Strength

Park

2017

Applied Sciences

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“…Alwash et al [12] have tested the quality of accuracy of various models according to the number of cores using the statistical indicators RMSE for rebound and UPV. This study used synthetic data with three levels of measurement quality (low, medium and high).…”

Section: Resultsmentioning

confidence: 99%

“…Authors in [11,12] carried out an investigation using a synthetic simulation. More recently, Ali-Benyahia et al [13] analysed these parameters on a recent real case study where 205 cores were tested and more than 155 structural elements (beams, columns and shear walls) were tested by RH and UPV.…”

Section: Cmss-2017mentioning

confidence: 99%

Prediction of concrete strength by non-destructive testing in old structures: Effect of core number on the reliability of prediction

2018

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Abstract.When assessing the quality of concrete on site, it is necessary to base the interpretation on reliable and representative test results. Generally, core tests are the most reliable and effective method for assessing the quality of concrete. Unfortunately, this type of testing is expensive and time consuming and only a limited number of cores can be carried out in practice. Non-destructive tests (NDT) can be used to overcome these drawbacks. The most popular and widely used NDT methods for assessing concrete strength are rebound hammer (RH) and the ultrasonic pulse velocity (UPV). The use of these methods provide unreliable predictions unless their results are correlated to destructive tests. A sufficient number of cores is needed to accurately predict the compressive strength of concrete. Recent researches have been carried out for identifying and optimizing the number of cores able to stabilize the calibration model on data from recent structures and from synthetic data. However, more case studies are needed to draw conclusions. In addition, the effect of the degradation of reinforced concrete elements on the number of cores needed for obtaining a reliable prediction needs to be investigated. In this paper, RH and UPV in conjunction with core tests are used to evaluate the concrete compressive strength in existing structures built in the 1970s and degraded mainly by steel corrosion.More than 234 elements were tested by RH and 86 elements by UPV. Also, 36 cores were drilled and tested under compression. A regression analysis is adopted to establish the correlations between NDT and strength measurements. The accuracy of the predictive assessment was evaluated using two indicators: the root mean square error (RMSE) and the coefficient of determination (r 2 ). The results of this case study showed that seven to nine cores is the minimal number of cores that guarantees the improvement of concrete strength assessment by combined or single NDT methods.

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“…In this very active field for research, one can also consider some recent interesting ideas which have emerged these recent years, like: the analysis of various scales of heterogeneity in an existing building [10], which can take benefit of a dense mapping of the structure with NDT measurements, the added value than can be derived from conditional coring, which corresponds to define the location of concrete cores on the basis of prior NDT results, instead of following a preconceived sampling scheme ( [11][12]), changing the conversion model identification techniques for better addressing the concrete variability [13].…”

Section: Rilem Tc 249-isc Agendamentioning

confidence: 99%

Reliable non-destructive strength assessment in existing structures: myth or reality?

Breysse

Balayssac

2019

RILEM Tech Lett

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The non-destructive assessment of concrete strength in existing structures is a complex issue which has been analyzed by a recently closed RILEM committee (TC 249-ISC) whose Guidelines and Recommendations are to be released soon. This committee has considered the state of practice, the yet existing standards and most recent innovative research results, in order to write recommendations that would improve the reliability of strength assessment with non-destructive techniques (NDT). These recommendations are based on a paradigm change: the challenge is not that of finding the true local strength, but that of estimating its value with a controlled tolerance interval and a limited risk of being wrong. Three levels of requirements are defined which correspond to different tolerance intervals on the assessed parameters and to a different amount of resources devoted to the investigation. While most of research has been devoted until now to the identification of relevant conversion models between NDT test results and strength, we have shown that the priority had to be put on other items, including the assessment of the NDT test results repeatability, the relevant definition of core locations and the checking of the final predictive error. This paper briefly describes the main innovations included in these recommendations.

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Non-destructive assessment of both mean strength and variability of concrete: A new bi-objective approach

Cited by 47 publications

References 13 publications

Estimation of Compressive Strength of High Strength Concrete Using Non-Destructive Technique and Concrete Core Strength

Estimation of Compressive Strength of High Strength Concrete Using Non-Destructive Technique and Concrete Core Strength

Prediction of concrete strength by non-destructive testing in old structures: Effect of core number on the reliability of prediction

Reliable non-destructive strength assessment in existing structures: myth or reality?

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