Earth buildings with local materials: Assessing the variability of properties measured using non-destructive methods

Barnaure, Mircea; Bonnet, Stéphanie; Poullain, Philippe

doi:10.1016/j.conbuildmat.2021.122613

Cited by 27 publications

(14 citation statements)

References 55 publications

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“…Indeed, the silt content based on this system is 44% and the sand content is 48%. The average value of raw earth density is 1878 kg•m −3 [25]. Furthermore, the Atterberg limits were reached using the NF EN ISO 17892-12 standard [26].…”

Section: Raw Earthmentioning

confidence: 99%

Experimental Characterization of Raw Earth Properties for Modeling Their Hygrothermal Behavior

et al. 2022

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Raw earth is one of the oldest building materials of mankind. Almost a third of the world’s population is living in an earth-based house. However, their use remains low compared to conventional materials such as concrete, steel, and wood. Although these geosourced materials are abundant, recyclable, and have a low environmental footprint, their use is very limited in the construction sector. This can be explained by the lack of data regarding their hygrothermal behavior. In this context, the present work aims to highlight the properties of cob construction material with straw addition. An experimental characterization of hygrothermal and microstructural properties has been carried out. Thermal conductivity, specific heat, sorption isotherms, moisture storage capacity, moisture buffer value (MBV), and water vapor permeability are obtained experimentally. Then, the collected data are used as input parameters of a numerical prediction model to numerically assess the thermal and hygric behavior. Cob is then compared to other more commonly used materials to highlight the benefits of its use within the context of the energetic and environmental transition. Our results will allow better understanding of the behavior of the new geosourced material thanks to experimental and numerical investigation.

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Section: Raw Earthmentioning

confidence: 99%

Experimental Characterization of Raw Earth Properties for Modeling Their Hygrothermal Behavior

et al. 2022

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“…The application of the resonance frequency measurements on the stabilized soil specimens is a proven technique with high repeatability due to its non-destructive nature (Barnaure et al, 2021;Dimter et al, 2016;Multon et al, 2022;Di Sante et al, 2022). Figs.…”

Section: Tab 2 Mixtures Of the Proportions Of Stabilizing Agents (Bin...mentioning

confidence: 99%

Hardening Accelerators (X-Seed 100 BASF, PCC, LKD and SALT) as Strength-Enhancing Admixture Solutions for Soil Stabilization

Lindh

Lemenkova

2023

Slovak Journal of Civil Engineering

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This study is aimed at evaluating the strength of stabilised soil collected from the Port of Norvik, Stockholm, Sweden, where 350,000 m3 of clay had to be stabilized. The tests were performed in the laboratory of the Swedish Geotechnical Institute (SGI). The soil was stabilised by binder mixtures using Portland cement clinker (PCC) and lime and lime kiln dust (LKD). Accelerators (X-seed 100 BASF, PCC, LKD and salt) were added to the soil samples for quicker stabilization. The strength of the stabilised soil was assessed using resonance frequency measurements of seismic P-waves by an ICP accelerometer in order to estimate the shear strength of the soil and to evaluate the effects from the accelerators, binder ratios, and the curing temperature on the gains in stabilization and strength. Various proportions of the binders were tested, i.e.: 50/50 cement/lime and 50/50 PCC/lime. The temperature was measured using a calorimeter in double experiments. The results showed that the accelerators improve the strength in the stabilized specimens and enhance the soil performance for engineering construction work.

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“…When the density is low, typically below 1300 kg m −3 , the heat transfer is mainly driven by the resistance in the air bulks, very present in materials heavily loaded with fibres. As many authors suggest, thermal conductivity can be established as a linear function of density [10][11][12][13][14][15][16][17][18][19][20]. When the density is higher than approximately 1300 kg m −3 , the thermal conductivity no longer varies linearly with the density.…”

Section: Cob Thermal Diffusivity Effusivity Heat Capacity and Densitymentioning

confidence: 99%

“…Although the literature is comprised of several studies focused upon the characterization of earth building materials properties, as presented above, the possibility of using local earth materials combined with available building techniques raises feasibility questions. Thus, Barnaure et al [14] emphasized this aspect in their study, evaluating the use of local earth materials and traditional construction methods alongside the variability of properties based on the repeatability of tests and correlations. They used raw earth, manufactured from the Guérande region, with two formulations: without fibres or using hemp shiv and reed fibres.…”

Section: Introductionmentioning

confidence: 99%

Novel Dual Walling Cob Building: Dynamic Thermal Performance

et al. 2021

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This paper emphasizes the experimental and numerical study of new cob mixes used for insulation and load bearing wall elements. The experimental study provides complete datasets of thermal properties of the new walling materials, using cob with density ranging from 1107 kg/m3 to 1583 kg/m3 for structural walls and less than 700 kg m−3 for insulation walls. Various mixes of French soils and fibres (reed, wheat straw, hemp shiv, hemp straw, and flax straw) with different water contents are studied. The lowest average thermal conductivity is obtained for the structural cob mix prepared of 5% wheat straw and 31% of water content. The insulation mix, prepared with 25% reed and 31% water content, has the lowest thermal conductivity. Investigation of diffusivity, density, and heat capacity shows that, when thermal conductivity is lower than 0.4 W m−1 K−1, the decrease in cob density leads to better insulation values and higher heat capacity. Little variation is noticed regarding the density and heat capacity for cob mixes with thermal conductivity higher than 0.4 W m−1 K−1. Furthermore, the non-uniformity of local thermal conductivity and heat losses through the samples is due mainly to the non-uniform distribution of fibres inside the mixes inducing an increase in heat loss up to 50% for structural walls and 25% for insulation walls. Cob thermal properties are used in a comparative simulation case study of a typical house under French and UK climatic conditions. The energy performance of the conventional building is compared to a dual walled cob building, showing remarkable reduction in energy consumption as the cob walls, whilst maintaining comfortable indoor conditions without additional heating.

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Earth buildings with local materials: Assessing the variability of properties measured using non-destructive methods

Cited by 27 publications

References 55 publications

Experimental Characterization of Raw Earth Properties for Modeling Their Hygrothermal Behavior

Experimental Characterization of Raw Earth Properties for Modeling Their Hygrothermal Behavior

Hardening Accelerators (X-Seed 100 BASF, PCC, LKD and SALT) as Strength-Enhancing Admixture Solutions for Soil Stabilization

Novel Dual Walling Cob Building: Dynamic Thermal Performance

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