Temperature dependence of the sorption isotherms of cement-based materials: Heat of sorption and Clausius–Clapeyron formula

Poyet, Stéphane; Charles, Sébastien

doi:10.1016/j.cemconres.2009.07.018

Cited by 107 publications

(49 citation statements)

References 36 publications

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“…Some authors use the term "adsorption" by generalizing the IUPAC nomenclature (International Union of Pure and Applied Chemistry) [13][14][15] and by including surface adsorption and capillary condensation together in the same definition [16,4,[17][18][19]. Other authors prefer using the term "sorption" to represent the uptake of water molecules [20,21].…”

Section: Modelling Of Hysteresismentioning

confidence: 99%

“…These studies have emphasised the necessity of considering hysteresis for predicting moisture behaviour in cementitious materials. Cement and Concrete Research 68 (2015) [10][11][12][13][14][15][16][17][18][19][20][21][22][23] Derluyn et al [11] concluded "durability risks may be underestimated when omitting moisture hysteresis". Johannesson et al [7] even argued that "the error in determining the water content may be as high as 30-35%" for the non-hysteresis modelling.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modelling of moisture transfers with hysteresis within cementitious materials: Verification and investigation of the effects of repeated wetting–drying boundary conditions

Zhang

Thiéry²,

Baroghel-Bouny³

2015

Cement and Concrete Research

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a b s t r a c tIn natural environment, the cover layer of reinforced concrete structures is affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on drying of materials. In this study, a method coupling a moisture transport model with any kind of hysteresis modelling is presented. Two hysteresis models (conceptual and empirical) have been implemented and compared. The scope of the study is limited to cyclic variations of RH with no direct contact with liquid water during the wetting steps. Experimental data verifications show that the conceptual approach yields better results than the empirical one. Comparisons of non-hysteresis and hysteresis modellings have been carried out for different cycle durations, RH amplitudes and initial moisture states. All comparisons and investigations enhance the necessity of considering hysteresis to quantify moisture transport under repeated drying-wetting boundary conditions.

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Section: Modelling Of Hysteresismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical modelling of moisture transfers with hysteresis within cementitious materials: Verification and investigation of the effects of repeated wetting–drying boundary conditions

Zhang

Thiéry²,

Baroghel-Bouny³

2015

Cement and Concrete Research

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“…For a given relative humidity, the water content of the material decreases when temperature increases. This phenomenon is mainly due to thermodynamical evolution of physisorption processes [45] [44]. Actually, the adsorption process being exothermic, an increase in temperature limits M A N U S C R I P T…”

mentioning

confidence: 99%

Hygric and thermal properties of hemp-lime plasters

Mazhoud

Collet

Prétot

et al. 2016

Building and Environment

124

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To cite this version:Brahim Mazhoud, Florence Collet, Sylvie Pretot, Julien Chamoin. Hygric and thermal properties of hemp-lime plasters.Building and Environment, Elsevier, 2016Elsevier, , 96, pp.206-216. 10.1016Elsevier, /j.buildenv.2015 M A N U S C R I P T A C C E P T E D AbstractHemp-lime mortars are generally used as indoor insulating plasters of building envelopes. They can be applied in thick coat to allow high enough hygrothermal performances to be reached in retrofit case. This study investigates hygric and thermal properties of two hemp-lime plasters. These plasters are made with the same lime-based binder and differ from their kind of hemp shiv. The two kinds of hemp shiv are defibered but one is smaller than the other. This experimental study is based on the measurement of sorption isotherm, water vapour permeability, moisture buffer value and thermal properties (conductivity and diffusivity). The effect of temperature on moisture buffer value and on thermal properties is also investigated. It is shown that hemp-lime plasters are hygroscopic and breathable materials. They are good hygric regulators according to the Nordtest classification and their moisture buffering ability is slightly impacted by temperature in the range from 11° to 23°C. The hemp-lime plaster with the smallest hemp M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT2 shiv is a better hygric regulator than the one with the biggest hemp shiv. Hemp-lime plasters show a quite low thermal conductivity, around 0.2 W/(m.K). The hemp-lime plaster with the smallest hemp shiv is slightly more conductive than the one with the biggest hemp shiv. The temperature does not impact thermal conductivity at dry state. At wet state, for a given relative humidity, when the temperature increases the thermal conductivity decreases simultaneously with water content. This study underlines that hemp-lime plasters show high hygrothermal qualities.

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“…After reaching the equilibrium time, the samples were centrifuged and the concentrations of AbA were obtained from calibration curve of UV-VIS spectrophotometer at fixed wave length of 242 nm (Perkin Elmer Lambda-40). The isosteric heat of adsorption q ST was calculated by Clausius-Clapeyron equation using equation 1: [14][15][16] where [AbA] corresponds to the equilibrium concentration. The isosteric heat of adsorption can be calculated from a ln [C] versus 1/T plot, at the same level of coverage.…”

Section: Abietic Acid Adsorption Isothermsmentioning

confidence: 99%

Study of the Catalytic Conversion and Adsorption of Abietic Acid on Activated Carbon: Effect of Surface Acidity

Garcı́a

Peralta

Segura

et al. 2016

J. Chil. Chem. Soc.

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This study reports the adsorption and catalytic conversion of abietic acid as representative compound of tall oil, using activated carbons. Acid functional groups present on CGRAN activated carbons favored the adsorption of abietic acid, probably through a physical adsorption mechanism. In contrast, the conversion of abietic acid was not favored in DARCO activated carbon by increase of acid sites thought HNO 3 treatment. The detection of neoabietic, palustric and/or levopimaric acids as reaction products indicate that the transformation of abietic acid was by dehydrogenation and/or isomerization routes. The negative influence of acid sites on the catalytic activity, in addition to the non-detection of volatile products, suggests that the cracking pathway for the conversion of abietic acid over these catalysts can be ruled out. Contrasting effects of the surface groups on the adsorption capacity and the conversion was observed: strong acid sites of CGRAN activated carbon favor the adsorption of abietic acid and decrease competitive adsorption between substrate and solvent, while conversion is not favored by these acid sites.

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Temperature dependence of the sorption isotherms of cement-based materials: Heat of sorption and Clausius–Clapeyron formula

Cited by 107 publications

References 36 publications

Numerical modelling of moisture transfers with hysteresis within cementitious materials: Verification and investigation of the effects of repeated wetting–drying boundary conditions

Numerical modelling of moisture transfers with hysteresis within cementitious materials: Verification and investigation of the effects of repeated wetting–drying boundary conditions

Hygric and thermal properties of hemp-lime plasters

Study of the Catalytic Conversion and Adsorption of Abietic Acid on Activated Carbon: Effect of Surface Acidity

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