The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Jérémie Saint-marc - One of the best experts on this subject based on the ideXlab platform.
-
The Effect of Undrained Heating on a Fluid-saturated Hardened Cement Paste
Cement and Concrete Research, 2009Co-Authors: Siavash Ghabezloo, Jean Sulem, Jérémie Saint-marcAbstract:Abstract The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well Cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated Hardened Cement Paste. The measured value of the thermal pressurization coefficient is equal to 0.6 MPa/°C. The drained and undrained thermal expansion coefficients of the Hardened Cement Paste are also measured in the heating tests. The anomalous thermal behaviour of Cement Paste pore fluid is back analysed from the results of the undrained heating test.
-
Poromechanical behaviour of Hardened Cement Paste under isotropic loading
Cement and Concrete Research, 2008Co-Authors: Siavash Ghabezloo, Jean Sulem, Sylvine Guédon, Francçois Martineau, Jérémie Saint-marcAbstract:The poromechanical behaviour of Hardened Cement Paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume, pore volume, solid volume, porosity and drained bulk modulus are discussed. A phenomenon of degradation of elastic properties is observed in the test results. The microscopic observations showed that this degradation is caused by the microcracking of the material under isotropic loading. The good compatibility and the consistency of the obtained poromechanical parameters demonstrate that the behaviour of the Hardened Cement Paste can be indeed described within the framework of the theory of porous media.
-
The effect of undrained heating on a fluid-saturated Hardened Cement Paste
Cement and Concrete Research, 2008Co-Authors: Siavash Ghabezloo, Jean Sulem, Jérémie Saint-marcAbstract:The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well Cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated Hardened Cement Paste. The measured value of the thermal pressurization coefficient is equal to 0.6MPa/°C. The drained and undrained thermal expansion coefficients of the Hardened Cement Paste are also measured in the heating tests. The anomalous thermal behaviour of Cement pore fluid is back analysed from the results of the undrained heating test.
Siavash Ghabezloo - One of the best experts on this subject based on the ideXlab platform.
-
Drained and Undrained Creep of Hardened Cement Paste under Isotropic Loading
CONCREEP 10, 2015Co-Authors: Siavash Ghabezloo, Jean SulemAbstract:The experimental results of isotropic compression tests performed at 20°C and 90°C on a class G Hardened Cement Paste (Ghabezloo et al., 2008, Cem. Conc. Res. 38, 1424-1437) have been revisited considering time-dependent response. Within the frame of a viscoplastic model, the non-linear responses of the volumetric strains as observed in drained and undrained tests and of the pore pressure in undrained tests are analysed. The calibration of model parameters based on experimental data allows to study the effect of the test temperature on the time-dependent response of Hardened Cement Paste.
-
Time-dependent behaviour of Hardened Cement Paste under isotropic loading
Cement and Concrete Research, 2012Co-Authors: Jean Sulem, Siavash Ghabezloo, Jean-benoît Laudet, Andre Garnier, Sylvine GuédonAbstract:Abstract The experimental results of isotropic compression tests performed at 20 °C and 90 °C on a class G Hardened Cement Paste hydrated at 90 °C (Ghabezloo et al., 2008, Cem. Conc. Res. 38, 1424–1437) have been revisited considering time-dependent response. Within the frame of a viscoplastic model, the non-linear responses of the volumetric strains as observed in drained and undrained tests and of the pore pressure in undrained tests are analysed. The calibration of model parameters based on experimental data allows to study the effect of the test temperature on the viscous response of Hardened Cement Paste showing that the creep is more pronounced for a higher test temperature. The effect of the hydration temperature on the time dependent behaviour is also studied by evaluating the model parameters for a Cement Paste hydrated at 60 °C. The time-dependent deformations are more pronounced for hydration at a higher temperature.
-
The Effect of Undrained Heating on a Fluid-saturated Hardened Cement Paste
Cement and Concrete Research, 2009Co-Authors: Siavash Ghabezloo, Jean Sulem, Jérémie Saint-marcAbstract:Abstract The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well Cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated Hardened Cement Paste. The measured value of the thermal pressurization coefficient is equal to 0.6 MPa/°C. The drained and undrained thermal expansion coefficients of the Hardened Cement Paste are also measured in the heating tests. The anomalous thermal behaviour of Cement Paste pore fluid is back analysed from the results of the undrained heating test.
-
Poromechanical behaviour of Hardened Cement Paste under isotropic loading
Cement and Concrete Research, 2008Co-Authors: Siavash Ghabezloo, Jean Sulem, Sylvine Guédon, Francçois Martineau, Jérémie Saint-marcAbstract:The poromechanical behaviour of Hardened Cement Paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume, pore volume, solid volume, porosity and drained bulk modulus are discussed. A phenomenon of degradation of elastic properties is observed in the test results. The microscopic observations showed that this degradation is caused by the microcracking of the material under isotropic loading. The good compatibility and the consistency of the obtained poromechanical parameters demonstrate that the behaviour of the Hardened Cement Paste can be indeed described within the framework of the theory of porous media.
-
The effect of undrained heating on a fluid-saturated Hardened Cement Paste
Cement and Concrete Research, 2008Co-Authors: Siavash Ghabezloo, Jean Sulem, Jérémie Saint-marcAbstract:The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well Cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated Hardened Cement Paste. The measured value of the thermal pressurization coefficient is equal to 0.6MPa/°C. The drained and undrained thermal expansion coefficients of the Hardened Cement Paste are also measured in the heating tests. The anomalous thermal behaviour of Cement pore fluid is back analysed from the results of the undrained heating test.
Giedrius Girskas - One of the best experts on this subject based on the ideXlab platform.
-
The effect of synthetic zeolite on Hardened Cement Paste microstructure and freeze-thaw durability of concrete
Construction and Building Materials, 2017Co-Authors: Giedrius Girskas, Gintautas SkripkiūnasAbstract:Abstract Tests were done with synthetic zeolite obtained by synthesizing alumina fluoride production residue, sodium hydroxide and alumina hydroxide. The synthesis lasted for two hours at 95 °C temperature. The obtained product was a mix of synthetic zeolite of modifications A and X. The binding material was Cement CEM I 42.5R. The test results revealed that substitution of Cement with 10% of synthetic zeolite reduces water absorption of Hardened Cement Paste ∼23.8%; the addition of air entraining admixture does not change the rate of water absorption. With the increase of zeolite content in concrete with and without air entraining admixture increases the volume of closed pores from 1.6% to 2.1% and from 4.1% to 7.6% respectively. The open porosity determined by water absorption of concrete with and without air entraining admixture changes insignificantly. The average distance between pores reduces from 360 μm to 190 μm when part of concrete is replaced by zeolite addition without air entraining admixture and from 190 μm to 130 μm in the case of using air entraining admixture. The addition of 10% of synthetic zeolite results in reduced content of portlandite and development of hydro aluminate compounds C 3 AH 6 (cubic crystals) in Hardened Cement Paste. Rose-shaped plates of calcium hydrosulphoaluminates (mono sulphate form) were also detected. These crystals together with hydroaluminates fill in the pores of Hardened Cement Paste and thus reduce the open porosity of concrete. Substitution of 10 wt% of Cement with synthetic zeolite addition increases the freeze-thaw resistance of concrete, i.e. reduces the loss of surface mass after 28 freeze-thaw cycles more than 1.6 times without the air entraining admixture and up to 3.5 times with air entraining admixture.
-
Cement freezing thawing resistance of Hardened Cement Paste with synthetic zeolite
Construction and Building Materials, 2014Co-Authors: Džigita Nagrockienė, Giedrius Girskas, Gintautas SkripkiūnasAbstract:Abstract This research article analyzes the synthetic zeolite is produced from the waste of AIF3 (amorphous SiO2), NaOH and Al(OH)3 by low-temperature (105 °C) synthesis and modified with CaCl2. The modified zeolite influence on freeze–thaw and de-icing salt resistance of the Hardened Cement Paste was tested with the replaCement of 5% and 10% of the Cement mass in the concrete by the zeolite additive. The specimens with 3% NaCl solution on the top surface were tested by one-sided freeze–thaw cycles. The scaled material content, the elongation of specimens and the ultrasonic pulse velocity were tested after every 7 cycles of freeze–thaw. Internal and surface X-ray diffraction patterns were obtained and analysed. The results of the investigation indicated significant improvement of freeze–thaw and de-icing salt resistance of the Hardened Cement Paste. High freeze–thaw with de-icing salt resistance was obtained by changes in the microstructure of the modified Cement Paste and Cement hydration products. The capillary porosity was reduced and the content of calcium silicate and aluminate hydrates was increased with reduction of Ca(OH)3 content in the Hardened Cement Paste. As a result a denser structure with different morphology of hydration products was obtained in the Hardened Cement Paste with synthetic zeolite additive from SEM images. The synthetic zeolite can be used as an additive for high freeze–thaw and de-icing salt resistance Cement products (concretes, mortars).
-
Cement freezing–thawing resistance of Hardened Cement Paste with synthetic zeolite
Construction and Building Materials, 2014Co-Authors: Džigita Nagrockienė, Giedrius Girskas, Gintautas SkripkiūnasAbstract:Abstract This research article analyzes the synthetic zeolite is produced from the waste of AIF3 (amorphous SiO2), NaOH and Al(OH)3 by low-temperature (105 °C) synthesis and modified with CaCl2. The modified zeolite influence on freeze–thaw and de-icing salt resistance of the Hardened Cement Paste was tested with the replaCement of 5% and 10% of the Cement mass in the concrete by the zeolite additive. The specimens with 3% NaCl solution on the top surface were tested by one-sided freeze–thaw cycles. The scaled material content, the elongation of specimens and the ultrasonic pulse velocity were tested after every 7 cycles of freeze–thaw. Internal and surface X-ray diffraction patterns were obtained and analysed. The results of the investigation indicated significant improvement of freeze–thaw and de-icing salt resistance of the Hardened Cement Paste. High freeze–thaw with de-icing salt resistance was obtained by changes in the microstructure of the modified Cement Paste and Cement hydration products. The capillary porosity was reduced and the content of calcium silicate and aluminate hydrates was increased with reduction of Ca(OH)3 content in the Hardened Cement Paste. As a result a denser structure with different morphology of hydration products was obtained in the Hardened Cement Paste with synthetic zeolite additive from SEM images. The synthetic zeolite can be used as an additive for high freeze–thaw and de-icing salt resistance Cement products (concretes, mortars).
-
Frost resistance of Hardened Cement Paste modified with synthetic zeolite
Engineering Structures and Technologies, 2013Co-Authors: Giedrius Girskas, Džigita Nagrockienė, Gintautas SkripkiūnasAbstract:Abstract The experiment was coducted using synthetic zeolite (modification A) obtained in the laboratory of Kaunas University of Technology by means of low-temperature synthesis (below 105 °C). Aluminium fluoride (AIF3) production waste as well as sodium hydroxide NaOH and aluminium hydroxide Al(OH)3were used to obtain a complex zeolite admixture. SEM analysis revealed that synthetic zeolite admixture was made of modification A zeolite and gypsite. SEM analysis results were confirmed by X-ray analysis. Three batches of specimens were made to determine the effect of synthetic zeolite admixture on the durability of Hardened Cement Paste. The first batch was without synthetic zeolite admixture, the second batch and the third batch contained 5 wt% and 10 wt% of synthetic zeolite admixture, respectively. Synthetic zeolite admixture was found to have a significant effect on the durability of the Hardened Cement Paste. The weight loss in the Hardened Cement Paste containing 5 wt% of the admixture was three times...
-
Microstructure Changes in Hardened Cement Paste after Freezing – Thawing Cycles
Materials Science, 2013Co-Authors: Gintautas Skripkiūnas, Džigita Nagrockienė, Giedrius Girskas, Jadvyga Kerienė, Eugenijus Janavičius, Algimantas ŠpokauskasAbstract:This article analyses the results of the freezing – thawing with deicing salt test where changes in the microstructure of the surface layer in contact with aggressive environment of Hardened Cement Paste produced with and without sodium silicate (hereinafter NTS) admixture were observed after freeze-thaw cycles in the presence of calcium chloride. After 56 cycles of freezing – thawing with deicing salt test micro-cracks and cavities were observed in the microstructure of the surface layer of Hardened Cement Paste with and without NTS admixture. In the case of Hardened Cement Paste with NTS admixture changes in the microstructure of the surface layer are less prominent: the number and size of cavities and micro-cracks are smaller. The test revealed that compressive stress, which before freezing – thawing with deicing salt test was very similar in Hardened Cement Paste with and without NTS admixture (85.4 MPa and 82.8 MPa respectively), changed after 56 cycles of freezing – thawing with deicing salt test as follows: reduced by 39.5 % in concrete without NTS admixture and increased slightly (2.5 %) in Hardened Cement Paste with NTS admixture. Based on the test results the authors arrived at the conclusion that sodium silicate solution can be effectively used to extend the useful life of Hardened Cement Paste exposed to freeze-thaw cycles and affected by CaCl 2 . DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3835
Gintautas Skripkiūnas - One of the best experts on this subject based on the ideXlab platform.
-
Cement freezing thawing resistance of Hardened Cement Paste with synthetic zeolite
Construction and Building Materials, 2014Co-Authors: Džigita Nagrockienė, Giedrius Girskas, Gintautas SkripkiūnasAbstract:Abstract This research article analyzes the synthetic zeolite is produced from the waste of AIF3 (amorphous SiO2), NaOH and Al(OH)3 by low-temperature (105 °C) synthesis and modified with CaCl2. The modified zeolite influence on freeze–thaw and de-icing salt resistance of the Hardened Cement Paste was tested with the replaCement of 5% and 10% of the Cement mass in the concrete by the zeolite additive. The specimens with 3% NaCl solution on the top surface were tested by one-sided freeze–thaw cycles. The scaled material content, the elongation of specimens and the ultrasonic pulse velocity were tested after every 7 cycles of freeze–thaw. Internal and surface X-ray diffraction patterns were obtained and analysed. The results of the investigation indicated significant improvement of freeze–thaw and de-icing salt resistance of the Hardened Cement Paste. High freeze–thaw with de-icing salt resistance was obtained by changes in the microstructure of the modified Cement Paste and Cement hydration products. The capillary porosity was reduced and the content of calcium silicate and aluminate hydrates was increased with reduction of Ca(OH)3 content in the Hardened Cement Paste. As a result a denser structure with different morphology of hydration products was obtained in the Hardened Cement Paste with synthetic zeolite additive from SEM images. The synthetic zeolite can be used as an additive for high freeze–thaw and de-icing salt resistance Cement products (concretes, mortars).
-
Cement freezing–thawing resistance of Hardened Cement Paste with synthetic zeolite
Construction and Building Materials, 2014Co-Authors: Džigita Nagrockienė, Giedrius Girskas, Gintautas SkripkiūnasAbstract:Abstract This research article analyzes the synthetic zeolite is produced from the waste of AIF3 (amorphous SiO2), NaOH and Al(OH)3 by low-temperature (105 °C) synthesis and modified with CaCl2. The modified zeolite influence on freeze–thaw and de-icing salt resistance of the Hardened Cement Paste was tested with the replaCement of 5% and 10% of the Cement mass in the concrete by the zeolite additive. The specimens with 3% NaCl solution on the top surface were tested by one-sided freeze–thaw cycles. The scaled material content, the elongation of specimens and the ultrasonic pulse velocity were tested after every 7 cycles of freeze–thaw. Internal and surface X-ray diffraction patterns were obtained and analysed. The results of the investigation indicated significant improvement of freeze–thaw and de-icing salt resistance of the Hardened Cement Paste. High freeze–thaw with de-icing salt resistance was obtained by changes in the microstructure of the modified Cement Paste and Cement hydration products. The capillary porosity was reduced and the content of calcium silicate and aluminate hydrates was increased with reduction of Ca(OH)3 content in the Hardened Cement Paste. As a result a denser structure with different morphology of hydration products was obtained in the Hardened Cement Paste with synthetic zeolite additive from SEM images. The synthetic zeolite can be used as an additive for high freeze–thaw and de-icing salt resistance Cement products (concretes, mortars).
-
Microstructure Changes in Hardened Cement Paste after Freezing – Thawing Cycles
Materials Science, 2013Co-Authors: Gintautas Skripkiūnas, Džigita Nagrockienė, Giedrius Girskas, Jadvyga Kerienė, Eugenijus Janavičius, Algimantas ŠpokauskasAbstract:This article analyses the results of the freezing – thawing with deicing salt test where changes in the microstructure of the surface layer in contact with aggressive environment of Hardened Cement Paste produced with and without sodium silicate (hereinafter NTS) admixture were observed after freeze-thaw cycles in the presence of calcium chloride. After 56 cycles of freezing – thawing with deicing salt test micro-cracks and cavities were observed in the microstructure of the surface layer of Hardened Cement Paste with and without NTS admixture. In the case of Hardened Cement Paste with NTS admixture changes in the microstructure of the surface layer are less prominent: the number and size of cavities and micro-cracks are smaller. The test revealed that compressive stress, which before freezing – thawing with deicing salt test was very similar in Hardened Cement Paste with and without NTS admixture (85.4 MPa and 82.8 MPa respectively), changed after 56 cycles of freezing – thawing with deicing salt test as follows: reduced by 39.5 % in concrete without NTS admixture and increased slightly (2.5 %) in Hardened Cement Paste with NTS admixture. Based on the test results the authors arrived at the conclusion that sodium silicate solution can be effectively used to extend the useful life of Hardened Cement Paste exposed to freeze-thaw cycles and affected by CaCl 2 . DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3835
Jean Sulem - One of the best experts on this subject based on the ideXlab platform.
-
Drained and Undrained Creep of Hardened Cement Paste under Isotropic Loading
CONCREEP 10, 2015Co-Authors: Siavash Ghabezloo, Jean SulemAbstract:The experimental results of isotropic compression tests performed at 20°C and 90°C on a class G Hardened Cement Paste (Ghabezloo et al., 2008, Cem. Conc. Res. 38, 1424-1437) have been revisited considering time-dependent response. Within the frame of a viscoplastic model, the non-linear responses of the volumetric strains as observed in drained and undrained tests and of the pore pressure in undrained tests are analysed. The calibration of model parameters based on experimental data allows to study the effect of the test temperature on the time-dependent response of Hardened Cement Paste.
-
Time-dependent behaviour of Hardened Cement Paste under isotropic loading
Cement and Concrete Research, 2012Co-Authors: Jean Sulem, Siavash Ghabezloo, Jean-benoît Laudet, Andre Garnier, Sylvine GuédonAbstract:Abstract The experimental results of isotropic compression tests performed at 20 °C and 90 °C on a class G Hardened Cement Paste hydrated at 90 °C (Ghabezloo et al., 2008, Cem. Conc. Res. 38, 1424–1437) have been revisited considering time-dependent response. Within the frame of a viscoplastic model, the non-linear responses of the volumetric strains as observed in drained and undrained tests and of the pore pressure in undrained tests are analysed. The calibration of model parameters based on experimental data allows to study the effect of the test temperature on the viscous response of Hardened Cement Paste showing that the creep is more pronounced for a higher test temperature. The effect of the hydration temperature on the time dependent behaviour is also studied by evaluating the model parameters for a Cement Paste hydrated at 60 °C. The time-dependent deformations are more pronounced for hydration at a higher temperature.
-
The Effect of Undrained Heating on a Fluid-saturated Hardened Cement Paste
Cement and Concrete Research, 2009Co-Authors: Siavash Ghabezloo, Jean Sulem, Jérémie Saint-marcAbstract:Abstract The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well Cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated Hardened Cement Paste. The measured value of the thermal pressurization coefficient is equal to 0.6 MPa/°C. The drained and undrained thermal expansion coefficients of the Hardened Cement Paste are also measured in the heating tests. The anomalous thermal behaviour of Cement Paste pore fluid is back analysed from the results of the undrained heating test.
-
Poromechanical behaviour of Hardened Cement Paste under isotropic loading
Cement and Concrete Research, 2008Co-Authors: Siavash Ghabezloo, Jean Sulem, Sylvine Guédon, Francçois Martineau, Jérémie Saint-marcAbstract:The poromechanical behaviour of Hardened Cement Paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume, pore volume, solid volume, porosity and drained bulk modulus are discussed. A phenomenon of degradation of elastic properties is observed in the test results. The microscopic observations showed that this degradation is caused by the microcracking of the material under isotropic loading. The good compatibility and the consistency of the obtained poromechanical parameters demonstrate that the behaviour of the Hardened Cement Paste can be indeed described within the framework of the theory of porous media.
-
The effect of undrained heating on a fluid-saturated Hardened Cement Paste
Cement and Concrete Research, 2008Co-Authors: Siavash Ghabezloo, Jean Sulem, Jérémie Saint-marcAbstract:The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well Cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated Hardened Cement Paste. The measured value of the thermal pressurization coefficient is equal to 0.6MPa/°C. The drained and undrained thermal expansion coefficients of the Hardened Cement Paste are also measured in the heating tests. The anomalous thermal behaviour of Cement pore fluid is back analysed from the results of the undrained heating test.
