Effect of sorption capacity on thermo-mechanical properties of unfired clay bricks

Fgaier, Fayçal El; Lafhaj, Zoubeir; Chapiseau, Christophe; Antczak, Emmanuel

doi:10.1016/j.jobe.2016.02.011

Cited by 47 publications

(36 citation statements)

References 21 publications

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“…MBV results confirmed that unstabilised RE is a good passive air conditioner and that this ability is highly affected by the soil's characteristics [18,42,43]: P and ELS had a very positive MBV but presented a marked difference between the results. The difference among the results was generated by the different porosity and soil mineralogy of the mixtures: P had both a higher bulk and very fine porosity and a more hygroscopic clay fraction (mainly Illite, more hydrophilic than kaolinite, the main component of the clay fraction of ELS [44][45][46]), improving its MBV over ELS.…”

Section: Discussionsupporting

confidence: 58%

Reduction of rammed earth's hygroscopic performance under stabilisation: an experimental investigation

Arrigoni

Grillet

Pelosato

et al. 2017

Building and Environment

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a b s t r a c tOne of the acknowledged qualities of rammed earth (RE) is its moisture buffering capacity. Recently, stabilisation of RE has become a common practice to improve the mechanical resistance but very little is known about the effect that stabilisation has on hygroscopic properties. The present study aims to fill this gap by understanding the role that stabilisation plays in the buffering and sorption capacity of RE. The use of alternative stabilisers such as fly ash and calcium carbide residue and a comparison with traditional unstabilised RE (URE) have also been investigated. Moreover, the effect of weathering, simulated by cyclic wetting-drying, on hygroscopic performance has been analysed. Moisture Buffer Value (MBV) testing, moisture and nitrogen adsorption-desorption isotherms and mercury intrusion porosimetry were performed on stabilised samples to examine microstructural phenomena responsible for behavioural changes. URE was confirmed to be a good-to-excellent passive air conditioner according to the MBV scale but its performance seemed to be highly influenced by the soil particle size distribution and mineralogy. Based on the experimental outcomes of the mixtures investigated, stabilisation had a detrimental effect on the moisture buffer capacity of rammed earth, likely due to the inhibition of the physico-chemical interactivity between moisture and clays. Weathering had a variable effect on the buffering capacity, depending on the availability of unreacted particles in the matrix.

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Section: Discussionsupporting

confidence: 58%

Reduction of rammed earth's hygroscopic performance under stabilisation: an experimental investigation

Arrigoni

Grillet

Pelosato

et al. 2017

Building and Environment

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“…As a consequence, as water shows a higher thermal conductivity than air, the thermal conductivity of the sample is increasing. Furthermore at certain relative humidity rates, the water vapor contained in pores induces menisci generating thermal bridges [10]. Clay/rape-straw and clay/sunflower bark and pith mixes show similar sorption-desorption behavior, their sorption curve is also similar to that of clay/sunflower bark at ρ1 density.…”

Section: Fig 3 Thermal Conductivity Versus Density Of Several Clay/vmentioning

confidence: 94%

“…This hysteretic behavior is usually explained in concretes by a combination of phenomenon: capillary condensation hysteresis, contact angle hysteresis and ink-bottle effect [12]. El Fgaier et al study [10] showed that mass moisture content of unfired clay bricks could reached 3.5% at 95%HR. Here, from dry state to 98%HR the mass moisture content reached 17.2% for clay/rape straw sample, 16.9% for clay/sunflower bark and pith, 15.5% for clay/sunflower bark at ρ1 and 14.6% for clay/sunflower bark at ρ2.…”

Section: Fig 3 Thermal Conductivity Versus Density Of Several Clay/vmentioning

confidence: 98%

Hygrothermal Behavior of Clay - Sunflower (<i>Helianthus annuus</i>) and Rape Straw (<i>Brassica napus</i>) Plaster Bio-Composites for Building Insulation

Brouard

Belayachi

Hoxha

et al. 2017

AEF

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The aim of this experimental investigation is to study and compare hygrothermal properties of different materials based on vegetable aggregates and clay in order to prove the performance of the developed composite in the framework of BIOCOMP project. Crude earth is known to have very high capacities to regulate indoor humidity. Vegetable aggregate is characterized by high porosity leading also to very effective natural indoor climate regulators. Then, we expect the mix of these two material will to produce an insulation bio-composite with enhanced thermal and hygroscopic performance. Sunflower stem, rape straw and clay used in this investigation are considered as a very low carbon footprint because they are real local agricultural byproducts. Clay-sunflower and rape bio-composites seem to be appropriate and effective biobased insulating plasters, further investigations must be performed in order to characterize more accurately their interesting hygrothermal properties as long as the acoustical and mechanical aspects. Samples have been manufactured with four different vegetable aggregates (rape straw, sunflower bark, sunflower pith and a mix of sunflower pith and bark) at a same binder/aggregate ratio. The same clay soil is used as a binder for the four bio-composites. The thermal properties for the different bio-composites were obtained from the thermal conductivity measurements after various relative humidity, in order to evaluate the impact of the water content on the thermal parameters. For the hydraulic properties, the sorption-desorption isotherms for the four composites are obtained. The results show a significant effect of the different aggregates on the hygrothermal behavior of the bio-composite based on clay.

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“…Apart from affecting the mechanical properties of masonry units, humidity has a negative effect on their thermal properties as well. The thermal conductivity value of porous building materials increases rapidly with the increase in their moisture content; consequently, the insulation capacity decreases and the heat loss increases [4][5][6][7][8][9][10][11][12][13][14][15]. The increase in the thermal conductivity of a material with the increase in its moisture content is the direct result of the fact that water, which has replaced the air in the pores of the material, has a thermal conductivity value of 0.61 W/(mK) at air temperature [16], which is twenty-four times higher than that of air.…”

Section: Introductionmentioning

confidence: 99%

Influence of Freeze/Thaw Cycles on Mechanical and Thermal Properties of Masonry Wall and Masonry Wall Materials

et al. 2019

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In this study, the influence of freeze/thaw cycles on the mechanical and thermal properties of bricks and mortar as building parts of masonry walls, as well as the influence on the masonry wall itself is investigated. At the material level, the influence of freeze and thaw cycles on the mechanical and thermal properties of masonry components (bricks and mortar) was investigated; at the construction level, the influence of freeze and thaw cycles on the mechanical and thermal properties of a masonry wall was studied. To study the influence of freezing on the energy demand characteristics of masonry buildings, in terms of energy conservation and greenhouse gas emission, a case study was investigated on a typical structure of a historical building located in Croatia, that had undergone a process of energy certification. The applied freeze/thaw regime negatively influenced the compressive strength and the thermal properties of bricks and mortar, as well as the mechanical and thermal properties of the wall. Considering the thermal properties of the material before and after its exposure to freeze/thaw cycles, we concluded that the annual energy consumption, the heating costs, and the CO2 emission of a family house could increase up to 3.7% after frost action in the studied case.

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Effect of sorption capacity on thermo-mechanical properties of unfired clay bricks

Cited by 47 publications

References 21 publications

Reduction of rammed earth's hygroscopic performance under stabilisation: an experimental investigation

Reduction of rammed earth's hygroscopic performance under stabilisation: an experimental investigation

Hygrothermal Behavior of Clay - Sunflower (<i>Helianthus annuus</i>) and Rape Straw (<i>Brassica napus</i>) Plaster Bio-Composites for Building Insulation

Influence of Freeze/Thaw Cycles on Mechanical and Thermal Properties of Masonry Wall and Masonry Wall Materials

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