Zoubir Mehdi Sbartaï

University of Bordeaux · I2M Civil Engineering Department

Machine learning has become a key branch in artificial intelligence by providing unique predictive modeling solutions. Predicting the compressive strength of concrete determined using non-destructive test techniques (NDT) includes high levels of uncertainty. This uncertainty directly depends on the repeatability of the measurement and the variabili...

Nowadays, the diagnosis of degraded concrete in existing reinforced concrete structures and the evaluation of their structural capacity has become an important issue in the construction industry. The accuracy of core tests and their locations have a major role in the evaluation methodology and the accuracy of results. An incorrect or inaccurate int...

Estimation of in-situ concrete compressive strength in existing structures is considered as a crucial step in assessing structural capacity. Destructive testing (DT) by coring in conjunction with non-destructive testing (NDT) offers an interesting method for concrete strength assessment in existing constructions. The non-destructive assessment of i...

This paper presents a review on combining NDT techniques, such as rebound hammer and ultrasonic pulse velocity, for assessing concrete compressive strength. These methods, though being favorably not invasive and easy to be extended to a larger number of elements, are affected by many contingency factors. The SonReb technique suggests combining the...

An experimental investigation of a non-linear mechanical phenomenon occurring in a masonry unit–mortar interface subjected to uniaxial monotonic and cyclic tensile tests is conducted in this study. Some crucial parameters, such as stiffness degradation, residual displacement, damage energy, and plasticity/friction energy were estimated based on cyc...

L’étude du comportement du béton sous l’effet de la température est primordiale afin d’évaluer le niveau de sécurité des structures sous sollicitations thermiques (cas des structures nucléaires par exemple). En effet, le chargement thermique conduit à plusieurs mécanismes d’endommagement responsables de la fissuration du béton. Une investigation ex...

The capitalization and the analysis of historical information is nowadays a prerequisite for any effective risk management and assessment in a wide range of domains. Despite the development of mathematical models, procedures, support decision systems and databases, some engineering disciplines, such as civil engineering, remain resistant to the use...

In real practice, to assess concrete strength in structures, engineers usually use non-destructive tests (NDT) (e.g. rebound hammer or ultrasonic pulse velocity) in addition to destructive tests (DT) that are carried out on cores extracted from the structure. The results of these tests (NDT and DT) are used to identify a relationship (a conversion...

The capacity to detect changes in modal properties caused by structural response from those resulting from noises (environment, test conditions, etc.) is a major issue in vibration analysis. For timber-based structures monitoring, high uncertainty ratios in the measurements may prevent efficient modal parameter identification. Therefore, assessment...

The evaluation of the spatial variability of concrete properties is an important issue for a better diagnosis of reinforced concrete structures. The combination between destructive techniques and nondestructive techniques (NDT) is a common practice to establish relationships between concrete properties and NDT measurements. Concrete properties can...

RESUME La variabilité spatiale des propriétés mécaniques est une information importante à prendre en compte pour fiabiliser l'évaluation du comportement mécanique des structures en béton. Cette variabilité peut être déterminée par exemple à partir de la variabilité spatiale des observables CND lors du diagnostic des ouvrages en béton armé. L'object...

This chapter provides additional information about the “identification of conversion model” step and the “strength estimation” step as defined in the flowchart summarizing the RILEM recommendation. The advantages and limits of the various options are illustrated by analyzing the results of synthetic simulations. Based on the developed synthetic dat...

This chapter gives definitions and basics on statistics, as mean standard deviation, trueness, accuracy, uncertainty … The relation of test result precision with the number of test readings is emphasized. Theoretical considerations about the minimal distance between two test readings to ensure their dependency are presented.

Guidelines describe the general process of in-situ compressive strength assessment. This process is divided into three main steps, data collection (using nondestructive testing and destructive testing), model identification and strength assessment. Three estimation quality levels (EQL) are defined depending on the targeted accuracy of strength asse...

The concrete strength assessment process is influenced by uncertainties at many levels, including random measurement errors, sampling uncertainty and identification of the conversion model parameters. Therefore, instead of estimating the true value of the concrete strength, it is preferable to say that the objective of the assessment process is to...

A benchmark is carried out in order to compare how 13 experts define and can carry out an NDT investigation program and derive strength values from NDT measurements. The benchmark is based on simulations, which reproduces a synthetic data set corresponding to a grid of twenty 3m-high columns defining the structure of a building made up of beams and...

This chapter presents a summarized state of the art of the available methods (SonReb and new methodologies) for the combination of NDT measurements. This synthesis can be helpful for selecting NDT methods for the combination. The chapter also discusses in which condition it is convenient or not to apply the combination of methods. Several possible...

The main objective of test region (TR) identification is to define an efficient conversion model. The first part of the chapter aims a difficult question, the identification of test regions (TR) because each structure is specific and so it is impossible to give a unique methodology. Here, three different possibilities are proposed. The first one is...

This chapter gives definitions and basics on statistics, as mean standard deviation, trueness, accuracy, uncertainty … The relation of test result precision with the number of test readings is emphasized. Theoretical considerations about the minimal distance between two test readings to ensure their dependency are presented.

A benchmark is carried out in order to compare how 13 experts define and can carry out an NDT investigation program and derive strength values from NDT measurements. The benchmark is based on simulations, which reproduces a synthetic data set corresponding to a grid of twenty 3m-high columns defining the structure of a building made up of beams and...

The concrete strength assessment process is influenced by uncertainties at many levels, including random measurement errors, sampling uncertainty and identification of the conversion model parameters. Therefore, instead of estimating the true value of the concrete strength, it is preferable to say that the objective of the assessment process is to...

Guidelines describe the general process of in-situ compressive strength assessment. This process is divided into three main steps, data collection (using nondestructive testing and destructive testing), model identification and strength assessment. Three estimation quality levels (EQL) are defined depending on the targeted accuracy of strength asse...

The main objective of test region (TR) identification is to define an efficient conversion model. The first part of the chapter aims a difficult question, the identification of test regions (TR) because each structure is specific and so it is impossible to give a unique methodology. Here, three different possibilities are proposed. The first one is...

This paper aims at investigating the performance of acoustic emission (AE) technique on material deterioration of masonry subjected to uniaxial monotonic and cyclic tensile loadings. The tested samples are composed of two limestone blocks bonded by thin lime mortar. The damage evolution was monitored and assessed by acoustic emission technique in 3...

This study aims to optimize the composition of new ecological concrete constituted of upgraded excavated soil. The novelty of this study is the fact that earth concrete is poured with classical vibration as ordinary concrete. Several soil concrete mixtures, composed of different proportions of clayey soil, sandy soil and small amounts of cement, li...

In-situ concrete strength assessment is commonly based on the implementation of Non-Destructive Tests (NDT) and coring of several specimens for Destructive Tests (DT). The most widely used non-destructive (ND) techniques are rebound hammer and ultrasonic pulse velocity. From the resulting data of NDT and compressive strength test results on specime...

One of the main interests of the Acoustic Emission (AE) technique is its capability to detect and localise damage in structures. In this paper, the accuracy of AE sources localisation in concrete is studied. Several methods related to the choice of the onset detection of AE signals and to the location algorithm are evaluated and compared. The resul...

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 recommen...

The diagnosis of reinforced concrete is essential to detect the degradation and thus maintain the structural performance of civil engineering structures. This paper aims to establish a mathematical relationship between the ultrasonic pulse velocity UPV (considered as an observable variable) and two concrete properties indicators (compressive streng...

For existing constructions, there is a need to estimate the concrete mechanical strength for a more accurate evaluation of their structural capacity. The destructive evaluation of strength by coring is expensive, sometimes technically difficult and it may be impossible in some situations and the evaluation is limited to a restricted surface of the...

In civil engineering, the follow-up of the structures’ concrete can be made by destructive testing. That is not possible in the case of nuclear power plants. So Non Destructive Evaluations are a solution for evaluating the concrete of the containment. NDEs are applied in civil engineering but each structure is a specific case due to its geometry, i...

ABSTRACT. To assess concrete strength in an existing structure, the current methodology combines nondestructive measurements (NDT) like rebound hammer or/and pulse velocity with destructive technique (cores) in order to implement a relationship known as ''conversion model" between the compressive strength and NDT measurements. However, the reliabil...

This paper addresses the use of non-destructive testing (NDT) methods to assess indicators for both the concrete durability (porosity, degree of saturation) and mechanical properties (elasticity modulus, compressive strength) of reinforced concrete structures. NDT results, called “observables”, are obtained by means of ultrasonic or electromagnetic...

Non-destructive techniques can be used in concrete structures for detection, localization (1D, 2D or 3D) or quantification. These three sets of objectives correspond to objectives of increasing ambition:. -in the first case, it is about detecting the presence of a defect, a singularity or a local variation of property: presence of a rebar, thicknes...

The evaluation of the properties of concrete is an important objective for managers and engineers of the diagnosis of structures. The contribution of non-destructive evaluation methods (NDE) is essential because it allows us to obtain information on the quality of the material or its durability without damaging the material examined. This evaluatio...

The aims of this chapter are to provide a description of the primary electromagnetic methods used to characterize concrete. Firstly, high and low frequency wave propagation techniques (radars and capacitive sensors) will be examined. The radar technique is more widely known for its ability to detect and locate steel reinforcements in concrete; howe...

The present study deals with the concrete cracking and damage monitoring during bending test. Notched three point bend specimens, with two different dimensions, were tested under crack mouth opening displacement. The acoustic emission (AE) technique was applied to monitor crack growth and characterize the crack development during bending tests. The...

Permittivity measurement of timber structures is important to ensure that its physical property lies within acceptable ranges. For example, permittivity dependence on moisture content can be useful to assess physical condition of wood. Permittivity is also a critical parameter that is needed for timber diagnosis using ground-penetrating radar (GPR)...

The non destructive (ND) assessment of concrete strength in existing structures is a complex challenge. Its quality depends on: the number of cores, the measurement uncertainties, the properties of concrete, especially its strength range, and variability, the quality of the conversion model which is used for deriving strength estimates from ND test...

The non destructive (ND) assessment of concrete strength in existing structures is a complex challenge. Its quality depends on: the number of cores, the measurement uncertainties, the properties of concrete, especially its strength range, and variability, the quality of the conversion model which is used for deriving strength estimates from ND test...

In this study, some NDTs (Ultrasonic Pulse Velocity UPV and Rebound Hammer) and uniaxial compressive test on microcores (UCSm) as a moderately destructive test, were investigated as tools for assessing the uniaxial compressive strength (UCS) of a soft limestone. Correlations between UCS and results of each above-mentioned tests were determined by a...

To assess concrete strength in a structure, nondestructive technique (NDT) like rebound hammer is combined with destructive technique (coring tests) in order to implement a relationship ‘‘conversion model” between the compressive strength and, NDT measurements. The conversion model is used to estimate the local strength value at each test location...

Strength assessment of concrete in existing structures is a key issue. Many non destructive techniques (NDT) are available which can provide information about the material condition and several approaches can be used to derive strength estimates from NDT test results. However, common practice suffers from many drawbacks: (a) it is difficult to asce...

Two functions are regularly tested on containment walls in order to anticipate a possible accident. The first is mechanical to resist a possible internal over-pressure and the second is to prevent leakage. The AAPR reference accident is the rupture of a pipe in the primary circuit of a nuclear plant. In this case, the pressure and temperature can r...

An international benchmark comparing a large variety of concrete strength assessment strategies was proposed by NDT experts of the RILEM committee TC-249. It was based on synthetic data and devoted to the estimation of average strength and concrete strength variability of a series of concrete columns of a single floor building using fixed budget. B...

The quality of concrete of the most of Algerian construction sites is often low. In the case of low compressive strength results, non-destructive tests such as rebound hammer and ultrasonic pulse velocity are performed to check these results. Correlations curves from either equipment manufacturers or from the literature are used by quality control...

The evaluation of the compressive strength of concrete in existing structures by coring is expensive, technically difficult in certain cases, and even impossible in others. The use of non-destructive testing (NDT) is an interesting alternative method (i.e. affordable cost, portable, fast, etc.). However, the NDT estimation of strength requires a pr...

This paper presents the results of a series of laboratory measurements, carried out to study how the ground-penetrating radar (GPR) signal is affected by moisture variation in wood material. The effects of the wood fibre direction, with respect to the polarisation of the electromagnetic field, are investigated. The relative permittivity of wood and...

Concrete cover evaluation with NDT technique is a critical issue in the diagnosis of structures service life. Ultrasonic NDT technique is one of the most efficient techniques for concrete strength evaluation. This paper presents the use of spectral analysis of ultrasonic surface waves for the nondestructive evaluation of concrete cover in laborator...

The moisture content of concrete is a critical parameter for most of the physicochemical pathologies, such as steel reinforcement corrosion, alkali-aggregate reaction, and freezing-and-thawing cycles. Therefore, the detection of moisture is important for the diagnosis of concrete structures at early stages of deterioration. The present study was un...

Non-destructive testing (NDT) techniques are interesting tools for assessing material properties while maintaining moderate cost. However, NDT measurements are sensitive to various concrete properties (e.g. moisture, porosity, strength, etc.). The combination of NDT techniques is then needed for decreasing the uncertainty and improving the structur...

The monitoring of concrete structures by the acoustic emission (AE) technique allows the detection and the localization of damage. The source location is determined by a triangulation algorithm based on the arrival time of AE signals recorded by sensors placed at the surface of the material, and the measured concrete wave velocity. The accuracy of...

This paper presents the results of a series of laboratory measurements carried out to study how the Ground Penetrating Radar (GPR) signal is affected by moisture variation in wood material. The effects of the wood fiber direction, with respect to the polarisation of the electromagnetic field, are investigated. The relative permittivity of wood and...

Using non-destructive techniques (NDT) like rebound hammer in combination with destructive techniques (DT) like core test is a common practice. Two approaches are widely used to produce a model for assessing the concrete strength. The first approach consists in fitting a specific model between NDT measurements and cores using the regression analysi...

Non-destructive techniques (NDT) like rebound hammer (RH) and ultrasonic pulse velocity (UPV) are widely used in conjunction with destructive techniques (core tests) for assessing the concrete strength in existing buildings. The methodology consists in fitting regression models between NDT techniques and destructive tests on a limited number of cor...

Strength assessment of concrete in existing structures is a key issue. Many NDT techniques are available which can provide information about the material condition and many models can be used to assess concrete strength from NDT results, but there is no way to establish what is the level of accuracy/confidence of concrete strength estimates. Since...

French Projects of Investment for the Future, called “Research for Nuclear Safety and Radiation Protection” have been initiated to further research on the causes, the management, the impact of the observed nuclear accidents and to propose and validate solutions to limit the risk and the consequences. In this context the "Non Destructive Evaluation...

Le bois est un matériau naturel de plus en plus utilisé dans la construction. Afin d'améliorer les outils de conception des structures en bois, la connaissance des mécanismes de fissuration est un élément primordial à appréhender. L'objectif de ce travail s'oriente vers l'étude des propriétés mécaniques et des mécanismes d'endommagement du bois mas...