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Materials and Structures

, 52:71 | Cite as

Recommendation of RILEM TC249-ISC on non destructive in situ strength assessment of concrete

  • Denys BreysseEmail author
  • Jean-Paul Balayssac
  • Samuele Biondi
  • David Corbett
  • Arlindo Goncalves
  • Michael Grantham
  • Vincenza A. M. Luprano
  • Angelo Masi
  • Andre Valente Monteiro
  • Zoubir Mehdi Sbartai
RILEM Technical Committee
  • 78 Downloads

Abstract

This recommendation is written to improve the assessment of the in situ. Compressive strength of concrete in existing structures by combining core strength values and non-destructive measurements. Both average strength and its scatter are considered. Deriving a characteristic strength from the assessment results is not considered here. The recommendation applies for most common techniques (ultrasonic pulse velocity, rebound hammer, pull-out) but also for less common techniques (penetration test, etc.). The recommendation does not apply to situations in which no core has been taken from the existing structure and is limited to situations where NDT is combined with cores. The recommendation introduces the concept of Estimation Quality Level, corresponding to the target of assessment, and which is put in relation with the means and strategy developed for assessing concrete. The text details all steps that must be followed from the data gathering to the checking of the quality of the final estimations. For more clarity, an illustrative example is described for each step of the assessment process.

Keywords

Concrete strength Model calibration Non-destructive techniques In-situ investigation Rebound hammer Strength assessment Ultrasonic pulse velocity 

List of symbols

a, b

Conversion model parameters

C

Calibration factor

CM

Calibration factor (scaling calibration)

COV

Coefficient of variation (= standard deviation/average value)

COVrep

Coefficient of variation of test results (for test result precision)

CS

Calibration factor (shift calibration)

EQL

Estimation quality level

est

Index for estimated values

fc

Concrete compressive strength

fc,est

Estimated concrete compressive strength

fc,est,cal

Estimated and calibrated concrete compressive strength

fc,est,o

Prior estimated concrete compressive strength

i

Index for measured values (from 1 to NTL for NDT test results, from 1 to Nc for core strength) or assessed values

j

Index for conversion model parameters (from 1 to Npar)

k

Index for NDT techniques

M

Conversion model (fc,est = M (Tr))

mean

Index designating the mean value of measured (test results, core strengths) or estimated properties (strength)

Nc

Number of cores

NDT

Non-destructive testing

Npar

Number of parameters of the conversion model

Nread

Number of readings (repetitions of individual measurements) in order to derive a test result

Nrep

Number of repetitions of a test in order to derive the test repeatability

NTL

Number of test locations (= number of NDT results)

parj

Value of the j-th conversion model parameter

r2

Determination coefficient

RH

Rebound hammer (for technique or test result)

RMSE

Root mean square error

RMSEfit

Fitting root mean square error, estimated on the identification set

RMSEpred

Prediction root mean square error, estimated when the conversion model is applied to new data

sd

Standard deviation

sdrep

Standard deviation of test results (for test result precision)

TL

Test location

TR

Test region

Tr

Test result

Tri

Value of the i-th NDT test result (when a single NDT is used)

Trk,i

Value of the i-th test result of the k-th NDT method (when several NDT are combined)

TRP

Test result precision

UPV

Ultrasonic pulse velocity (for technique or test result)

Notes

Acknowledgements

The authors of this RILEM TC 249-ISC gratefully acknowledge all contributors who are cited above and do not appear as full authors of the recommendation for administrative reasons.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

References

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Copyright information

© RILEM 2019

Authors and Affiliations

  • Denys Breysse
    • 1
    Email author
  • Jean-Paul Balayssac
    • 2
  • Samuele Biondi
    • 3
  • David Corbett
    • 4
  • Arlindo Goncalves
    • 5
  • Michael Grantham
    • 6
    • 7
  • Vincenza A. M. Luprano
    • 8
  • Angelo Masi
    • 9
  • Andre Valente Monteiro
    • 5
  • Zoubir Mehdi Sbartai
    • 1
  1. 1.University Bordeaux, I2M-UMR CNRS 5295TalenceFrance
  2. 2.INSA ToulouseLMDCToulouseFrance
  3. 3.University Chieti-PescaraChietiItaly
  4. 4.ProceqSchwerzenbachSwitzerland
  5. 5.LNECLisbonPortugal
  6. 6.Leeds UniversityLeedsUK
  7. 7.Sandberg LLPLondonUK
  8. 8.ENEABrindisiItaly
  9. 9.University BasilicataPotenzaItaly

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