Nicolas Burlion

• Polytech Lille

The Callovo-Oxfordian (COx) claystone is selected as the host rock in the French project for geological disposal of radioactive waste. In its initial state, the host rock is fully saturated. Due to the low permeability, the pore fluid pressure can locally evolve in a quasi undrained condition due to subsequent mechanical and thermal loading, and th...

This work is devoted to estimation of macroscopic failure strength of heterogeneous rock-like and cement-based materials. Three representative microstructures are considered, respectively with a random distribution of pores, stiff inclusions, and both pores and inclusions in a pressure-sensitive plastic solid matrix. In the first part, a series of...

This study investigates the effect of inclusion size on drying shrinkage cracking in cementitious materials. A series of laboratory desiccation tests on concrete with different size of inclusions are conducted. Nondestructive X‐ray micro‐tomography images were used to reconstruct the drying‐induced shrinkage cracks of samples in desiccation tests....

In this study, the influence of interface transition zone (ITZ) on the elastic properties of concrete and rock like heterogeneous materials is investigated. Direct simulations of a representative volume element are realized by using a fast Fourier transform based method and the obtained results are used as the reference solutions. Some widely used...

Depleted oil reservoirs have been one of the most practical options for CO2 sequestration. To ensure the overall sealing performance of oilwell for CO2 injection, it is necessary to understand the long-term hydro-mechanical behaviour of cement paste used as oilwell casing. In the presence of high CO2 concentration and water, cement paste is firstly...

Multi-scale models are developed for heterogeneous concrete materials to estimate their macroscopic mechanical properties in terms of micro-structural data. One crucial challenge of those models is the identification of local properties of constituent phases. In this paper, we present an efficient method based on Artificial Neural Networks (ANN). T...

Cement-based materials usually undergo drying which influences their mechanical behaviour. This study investigates the evolution of mechanical properties of a high-performance self-compacting concrete subjected to drying at an early age and after long-term maturation. Uniaxial compression and bending tests are performed at different drying times. T...

This paper is devoted to numerical modelling of cracking in concrete-like materials by explicitly taking into account microscopic heterogeneities. A numerical method based on peridynamics theory is proposed. The formulation and implementation of the numerical method are first presented. Its efficiency in modelling the initiation and propagation of...

In this paper, the creep deformations of two representative concrete materials are investigated under thermal-mechanical-hydric conditions. Both basic and drying creeps are considered. Triaxial compression creep tests are first performed under a confining pressure of 5 MPa and three different values of temperature (T = 20 °C, 50 °C or 80 °C). Two d...

This paper presents an experimental study on the influence of inclusion rigidity on the shrinkage cracking in a concrete composite. For this purpose, a series of concrete samples are casted with artificial inclusions of different rigidities. These samples are subjected to different levels of drying in order to evaluate cracks induced by the drying...

This work focuses on the study of macroscopic mechanical behavior of cement paste in relation with micro-structural degradation due to chemical leaching. According to experimental evidences, the degradation of cement paste is mainly characterized by a significant increase of porosity due to the dissolution of Portlandite (CH) and the decalcificatio...

The purpose of this experimental study is to highlight the effects of leaching (by ammonium nitrate solution) on time-dependent behaviour of an oil-well cement paste under the temperature of 90 °C. Uncoupled creep tests on sound and leached samples and coupled chemo-mechanical creep tests on initially sound samples are performed under confining pre...

Many engineering materials contain families of pores at different scales. In this study, a numerical homogenization analysis method is developed to describe the effective elastic and plastic properties of a class of porous materials with two populations of pores at two separated scales. The solid phase at the micro-scale is described by the Drucker...

The aim of this paper is to study effects of inclusion and pores on plastic and viscoplastic deformation of rock-like materials. We shall consider a class of clayey rocks with two separate scales of microstructure. At the mesoscopic scale, the material is constituted by a continuous matrix and embedded mineral inclusion. At the microscopic scale, t...

The aim of the present study is to extract the poral solution from cement pastes with high W/C ratio by a non-destructive method. The sample is placed in an hydrostatic cell under a confining pressure and an inert gas under high pressure is applied on the specimen to force a movement of interstitial water. As a result of the non-destructive nature...

The aim of the present study is to extract the pore solution from cement pastes and mortars with high W/C ratio by a non-destructive method. The sample is placed in a hydrostatic cell under a confining pressure and an inert gas under high pressure is applied at one end to force a movement of interstitial water. As a result of the non-destructive na...

This experimental study imposes limited relative humidity (RH) gradients to small mature concrete samples, at a constant temperature T = 20, 50 or 80°C. Mass loss and shrinkage are recorded until stabilization at each RH and T, for up to 1991 days. Firstly, our mass loss data are consistent with those presented in former research (on different samp...

This paper focuses on the evolution of shrinkage cracking in a geometrically simplified concrete, i.e. a composite made of cement matrix including the glass spheres. In the first part, the laboratory samples at different levels of drying are examined experimentally. In order to identify the occurrence of cracking as well as its evolution in a direc...

Le présent travail s’intéresse à l’effet de resaturation sur le comportement mécanique d’un mortier normal mature. Aussi, des essais de compression uniaxiale et triaxiale déviatorique ont-ils été réalisés en fonction de l’état de saturation (saturé, séché à 60°C jusqu’à poids constant, resaturé à différents degrés). Il a été observé que les résista...

Drying process of cementitious materials leads to cracks, especially in the presence of aggregates restraint, which has important consequences on transport and mechanical properties. This paper presents different effect on cracks generated in the drying process of cementitious composites under different conditions of inclusions. The non-destructive...

Based on relevant experimental data of a petroleum cement paste under mechanical loading and chemical leaching, an elastic-plastic model is first proposed by taking into account plastic shearing and pore collapse. The degradation of mechanical properties induced by the chemical leaching is characterized by a chemical damage variable which is define...

L'objectif de ce papier est de présenter un modèle basé sur les réseaux de neurones pour la modélisation des isothermes de désorption des pâtes de ciment en utilisant le rapport E/C comme seule variable du modèle. Etant donné que les réseaux de neurones utilisent le processus d'entraînement basé sur des résultats expérimentaux dans la construction...

When a cementitious material is in contact with ambient air, CO2 enters the material by the porous network and through the cracks, reacts with the hydrates CSH and Ca (OH)2 saturation degree of the material, it does not occur in a fully saturated with water or totally dry material. Thus, knowledge of isotherms, both for sorption and desorption, is...

The electrical resistivity, measurable in various ways by lab cell or multi probes surfaces device, is a technique used on soil and can be implemented in the analysis of concrete saturation and/or carbonation. This paper presents the experimental results of measurements of electrical resistivity tomography performed on slabs of concrete, mortars an...

The objective of this study is to show, using an accelerated experimental method, the influence of carbonation on desorption and adsorption isotherms of cementitious materials. The materials studied are made with cement CEM I. The samples used are of the thin discs of 37 mm diameter and 2 mm thick. The isotherms are obtained by gravimetric monitori...

The electrical resistivity of concrete, measurable in various ways by lab cell or multi probes surfaces device, is a technique used on soil and can be implemented in the analysis of saturation. The concrete under natural conditions where it is exposed to air, undergo the carbonation phenomenon due to the presence of atmospheric carbon dioxide CO2....

The aim of this study is to determine the Representative Volume Element (RVE) size related to the desorption isotherm on concrete. Slices of three thicknesses taken from cast cylinders of an OPC concrete were desorbed from fully saturated condition to the dry state. The slice thickness had no clear influence on the water content once mass stabiliza...

This study deals with the effect of re-saturation after drying on the evolution of the mechanical behaviour of a standard mortar. Uniaxial and triaxial compression tests were performed according to the saturation state (saturated, dried in an oven at 60 °C until constant weight, re-saturated with water in different proportions). The results obtaine...

This paper presents the first part of a theoretical and experimental work aiming at modeling the chemo-mechanical behavior of composites made up of ion exchange resins (IER) solidified in a tri-calcium silicate cement paste (C3S). Because of ion exchange processes, the volume change of the IER may cause internal pressures leading to the degradation...

The aim of the present study is to experimentally investigate the water vapor desorption and drying shrinkage of cement-based materials during a step-by-step desorption process, with the objective to link drying shrinkage to water desorption. Water vapor desorption isotherms of two cement pastes and two mortars (with water-to-cement ratio of 0.5 an...

One of the most important issues in civil engineering about structures is their durability. A structure during his lifetime faces different environmental situations, like different relative humidities, and different cycles of drying and saturation will be imposed on it, so it is very critical to characterize materials behavior against these changes...

The aim of present study is to determine experimentally the first desorption isotherm of a high performance concrete based on CEM I cement for long-term underground nuclear waste storage structures. Thin sliced samples are used in order to reduce the time needed to obtain the complete isotherm. To ensure the experimental representativeness, a great...

L’humidité dans les bétons et notamment l’existence d’un gradient en profondeur est un phénomène naturel lié au fait qu’il s’agit d’un matériau poreux qui échange avec son environnement. En particulier, la profondeur de carbonatation et de pénétration des chlorures sont généralement les deux témoins du vieillissement, recherchés lors d’un diagnosti...

In this paper, we present a predictive model, based on experimental data, to determine the macroscopic mechanical behavior of a material made up of ion exchange resins solidified into a CEM III cement paste. Some observations have shown that in some cases, a significant macroscopic expansion of this composite material may be expected, due to intern...

Analysis of chemical degradation effects on the thermo-hydro-mechanical (THM) behavior of petroleum cement paste is essential to the prediction of its durability. These effects are highlighted by comparing the results of mechanical tests at the non-degraded and completely degraded state of cementitious material at 90 °C. Triaxial compression tests...

This paper presents results of a study on moisture changes and strains induced by water desorption of cement based materials. Ordinary mortars and cement pastes with waterto- cement ratios of 0.5 and 0.8 were submitted to small steps of drying in order to avoid structural effects. Resulting data are of importance as they allow water retention curve...

One of the main objectives of the APPLET project was to quantify the variability of concrete properties to allow for a probabilistic performance-based approach regarding the service lifetime prediction of concrete structures. The characterization of concrete variability was the subject of an experimental program which included a significant number...

Concrete structures experience microcracking leading to mechanical damage when submitted to desiccation. This change in mechanical properties can be dependant on the level of drying and also on constituents of the material. This paper focuses on one particular aspect, which is to determine the role of the size of rigid inclusions over cementitious...

This chapter presents an elastoplastic model coupled with chemical degradation for a petroleum cement paste. This work is performed in the framework of a feasibility study for the acid gas sequestration in abounded reservoirs. Based on relevant experimental data and with the help of a phenomenological chemical model, the chapter first proposes a ge...

The objective of this work is to evaluate nine closed-form analytical expressions that describe the sorption isotherm across the complete range of water contents for cementitious materials.To meet this objective, the models were compared in terms of their accuracy root mean square error (RMSE), linearity (coefficient of determination, R2, and adjus...

The prediction of the service lifetime of civil engineering structures needs an appropriate comprehension and quantification of the physical, chemical and mechanical processes associated with the durability of structural reinforced concrete. In particular, the porosity is an essential property involved in degradation of concretes. Also, the develop...

This contribution aims at (1) determining experimentally the first desorption isotherms of two high performance concretes (based on CEM I and CEM V cements), at three different temperature levels T = 20, 50 and 80 °C, and (2) showing whether these may be simply described by adsorption and capillarity.Results at 20 °C compare well with recently publ...

One of the major technological issues for CO2 injection is the long-term behavior of the cement-based materials used to ensure the overall sealing performance of the storage wells. When water is present, the CO2 injected can react chemically with the cement (i.e. carbonation). The objectives of our experimental program are to assess the kinetics an...

The storage of CO2 is an expected solution by the oil industry: using petroleum wells as geological reservoirs is a very important and new research field. The durability of such storage has an importance to be predicted. The carbonation of oil-well cement (Class G type) under temperature (90 degrees C) is evaluated in this paper. In the first part...

Cement paste used in the Oil Industry is generally subjected to chemical degradation due to flow of acid fluids in various situations. The present study focuses on the evolution of thermo-hydro-mechanical (THM) behavior with chemical degradation of petroleum cement paste. Triaxial compression tests with different confining pressures (0, 3, 10 and 2...

Mechanical behaviour of cement-based materials is strongly influenced by drying. In order to evaluate only drying effects on mechanical behaviour, it is necessary to conduct the studies on mature materials, i.e. materials for which the strength increase due to hydration has already reached stabilization with an adequate curing regime. Previous stud...

Durability of concrete structures is strongly conditioned by the occurrence of several chemical and physical phenomena that can be linked to the displacement of water in the constitutive material. Previous studies have already emphasized that in moderate temperature and pressure conditions, water transfers in weakly permeable cementitious material...

The variation of permeability of typical petroleum cement paste is investigated as functions of mechanical loading and chemical degradation under the temperature of 90°C. In sound material, the permeability classically increases with deviatoric stress due to microcracks and volumetric dilatancy but decreases with confining pressure. Chemical leachi...

Design of underground nuclear waste disposal requires a full characterization of concrete under various thermo-hydro-mechanical and chemical condition. This experimental work concerns the characterization of coupled thermo-hydro-mechanical effects, and the concretes are made with cement CEM I or CEM V/A (according to European norms), allowing to st...

One of the major technological issues for CO2 injection (for EOR, CCS, etc.) is the long-term behavior of cement-based materials used to ensure the overall sealing performance of the storage wells. When water is present, the CO2 after injection can react chemically with the cement (i.e. carbonation). How do the CO2-enriched formation fluids changes...

Short and long-term behaviors of concrete structures are of importance when dealing with durability aspects. One particular interesting aspect is the change in microstructure of concrete submitted to drying or leaching processes, and a potentially induced cracking pattern. Experimental investigations which focus on the effect of the dimensions of a...

In the oil field, cement pastes are used during drilling operations, plugging and/or abandonment of the wells. Therefore, the understanding of the implied phenomena is important from a point of view of durability. This paper deals with the hydraulic behaviour of an oil cement paste submitted to chemical degradation and mechanical loading, under tem...

Chemical shock of cement based materials leads to significant degradation of their physical properties. A typical scenario is a calcium leaching due to water (water with very low pH compared with that of pore fluid). The main objective of this paper is to evaluate the evolution of microstructure induced by leaching of a cementitious composite using...

Chemical degradation of cement based materials leads to significant degradation of their physical properties. A typical scenario is calcium leaching due to water (water with very low pH compared to that of interstitial fluid). The main objective of the present study is to evaluate the evolution of micro-geometry induced by leaching of mortar using...

The aim of the present research was to study moisture changes and strains induced by smooth water desorption of several cement based materials. The main advantage of this small-steps drying is to dramatically limit the structural effect within tested samples, by lowering moisture gradients and therefore cracking due to differential shrinkage. Resul...

This paper presents experimental investigations of mechanical behaviour of a pure cement paste subjected to compressive stresses and chemical degradation. Two series of laboratory tests have been performed: decoupled and coupled chemical-mechanical tests. Hydrostatic and triaxial compression tests have first been realized respectively on sound and...

This study aims to give information, on the one hand, about the evolution of drying shrinkage according to mortar composition, and on the other hand, about the effects of hygro-mechanical microcracking on permeability of cementitious materials. It also deals with the influence of the interstitial fluid nature on the permeability. The results obtain...

This paper is devoted to a micromechanics-based simulation of the response of concrete to hydrostatic and oedometric compressions. Concrete is described as a composite made up of a cement matrix in which rigid inclusions are embedded. The focus is put on the role of the interface between matrix and inclusion which represent the interfacial transiti...

Cette étude expérimentale s'intéresse à l'effet de la dégradation chimique sur le comportement hydraulique d'une pâte de ciment, en fonction des sollicitations mécaniques sous température. Les essais réalisés montrent que la perméabilité diminue avec l'augmentation de la pression de confinement, de manière plus importante pour le matériau dégradé c...

This experimental study is interested in the chemical degradation effect on the hydraulic behaviour of a cement paste, according to the mechanical loading under temperature. The tests carried out show that the permeability decreases with increase in confining pressure, in a more important way for chemically degraded material. Under creep with weak...

The drying of mortar and concrete generally affects their elastic properties and strength. Such property variations are of interest, since they affect the durability of structures designed with these materials. Previous studies, conducted on two mortars with different W/C ratio, showed that drying such material led to decreases in their elastic mod...

This paper deals with experimental investigation and numerical modeling of drying effects on the mechanical behavior of cement-based materials. First, the main results from an experimental study on the mechanical behavior (failure strength, induced damage, and plastic deformation) of a mortar subjected to the desiccation process are presented. Then...

Un modèle élasto-plastique endommageable de comportement du béton est présenté. Ce modèle, basé sur les concepts d'endommagement isotrope développé par Mazars et de plasticité non associée, a été développé au Laboratoire de mécanique de Lille et mis en oeuvre dans le code de calcul MPPSAT du laboratoire pour les différents cas tests du benchmark pr...

Desiccation of concrete induces the formation of microcracks leading to mechanical damage of concrete structures. Damage concentrates in the interfacial contact zone (ICZ), like also between aggregate particles. This damage, induced by drying, can be characterized in function of the 'Saturation level degree' variations. The main purpose of this stu...

Concrete materials are submitted to drying when the relative humidity of their surrounding is decreasing. The main purpose of this study is to highlight the variation of multiaxial mechanical behaviour of mortars which depends on desiccation level and cement paste properties (quality). The behaviour under discussion includes uniaxial and triaxial s...

A new elastoplastic damage model is proposed to describe mechanical behaviour of cement based materials subject to multiaxial compressive stresses. A particular emphasis is put on the pressure sensitivity of plastic flow and damage evolution. Based on experimental data from a mortar subject to desiccation tests, the evolution of mechanical properti...

Leaching of cementitious materials leads to an increase in porosity, which has important consequences on transport and mechanical properties. The present study outlines the characterization of microstructural evolution in a mortar subjected to a chemical attack, by means of a powerful non-intrusive experimental method, namely synchrotron X-ray comp...

Cette étude vise à comprendre l’effet d’une microfissuration d’origine hygromécanique sur la perméabilité d’un mortier normal. Elle traite également de l’influence de la nature du fluide injecté sur les propriétés de transport. Ainsi, des mesures de perméabilité à l’argon et à l’éthanol avant fluage et après recouvrance, des mesures de porosité, de...

The objective of this work is experimental characterisation and numerical modelling of coupled behaviours between drying shrinkage and plastic damage in concrete. In the first part, we present an original experimental study on an ordinary concrete in order to determine material damage induced by drying shrinkage. Uniaxial compression tests are perf...

Résumé : Cette étude s'intéresse aux effets du séchage sur le comportement mécanique de deux mortiers de rapport eau/ciment égal à 0,5 et 0,8. Abstract : This study is interested in the drying effects on the mechanical behaviour of two mortars with water by cement ratio equal to 0.5 and 0.8. The shrinkage, uniaxial and triaxial compressive tests we...

The analysis of concrete structure durability is based on the investigation of the material long-term behaviour. Such behaviour is influenced by mechanical, hydrous and thermal actions applied to structures. The main purpose of this study concerns the characterisation of the coupled effects between drying shrinkage and damage for a cementitious mat...

The main objective of this present study was to evaluate, for a standard mortar, the drying effect on its mechanical behaviour. Numerous uniaxial compression tests were thus performed with loading-unloading cycles. They were carried out on different samples previously preserved under various conditions of conservation: preserved from desiccation, a...

The consequences of leaching, accelerated by ammonium nitrate, on samples of a standard mortar have been characterized in 3D by X-ray computed microtomography (XCMT). This non-destructive method provides quantitative 3D maps of the sample's X-ray absorption coefficient μ. At each voxel, the value of μ was the average of the absorption coefficients...

An elastoplastic and damageable model for concrete is presented. This model, based on concepts of isotropic damage developed by Mazars, and on non-associated plasticity, was developed in the laboratory of Mechanics of Lille, implemented in the MPPSAT finite elements code of the laboratory, and used for the various benchmark tests proposed by EDF. T...

Structural strength, porous space, and permeability of concrete are strongly affected by mechanical, hydrous, and thermal loading. These various loadings may lead to drying shrinkage, one of the main characteristics of this type of material, which has to be involved in the behaviour modelling and experimental investigations being the subjects of th...

The main objective of this present study is to evaluate, for a concrete and a normalised mortar, the drying effect on its mechanical behaviour. Numerous uniaxial compression tests were thus performed with loading-unloading cycles. They were carried out on different samples previously preserved under various conditions of conservation: preserved fro...

Cette étude vise à évaluer l'effet du séchage sur le comportement mécanique d'un béton et d'un mortier normal. Dans ce but, plusieurs dizaines d'essais de compression uniaxiale avec cycles de charge-décharge ont été réalisés en fonction du temps de séchage et du mode de conservation des éprouvettes (saturées en eau, laissées en dessiccation dans un...

Desiccation shrinkage of concrete and mortar induces the formation of microcracks leading to mechanical damage of concrete structures. This damage, induced by drying, can be characterized by time evolutions of the material elastic properties. The main purpose of this study is to propose an experimental campaign able to show this phenomenon. We pre...

Drying shrinkage of concrete induces the formation of microcracks that damage concrete structures.This damage can be characterised by deteriorating material elastic prop- erties over the years.In this investigation,we present a modelling of this phenomenon,simple and easy to be implemented,and that should allow engineers to predict cracking as a du...

The long term behaviour of cementitious materials depends on mechanical, hydraulic, physical and chemical degradation mechanisms and their coupling. This study aimed to evaluate the coupled effect between drying shrinkage and triaxial mechanical behaviour. A normal mortar (French norm) with a W/C ratio of 0.5 was cast and after 5 days, immersed in...

We present a numerical modelling of elastoplastic damage due to drying shrinkage of concrete in the framework of mechanics of partially saturated porous media. An elastoplastic model coupled with isotropic damage is first formulated. Two plastic flow mechanisms are involved, controlled by applied stress and suction, respectively. A general concept...

Compaction of concrete is physically a collapse of the material porous microstructure. It produces plastic strains in the material and, at the same time, an increase of its bulk modulus. This paper presents two experimental techniques aimed at obtaining the hydrostatic response of concrete and mortar. The first one is a uniaxial confined compressio...

The objective of this study is to develop a model for concrete with an emphasis on tension and compaction. Compaction of concrete is physically a collapse of the material voids. It produces plastic strains in the material and, at the same time, an increase of the bulk modulus. The model is based on mechanics of porous materials, damage and plastici...

Sewage sludges exhibit in most cases theological properties which do not allow us to classify them either as simple fluids or as solids. On one hand, they are not simple fluids because of their non-Newtonian, shearthinning and time-dependent (thixotropic or rheopectic) behaviour and because of the possibility for some of them of showing a yield str...