Experimental and numerical analysis of the hygric performance of earthen buildings after façade hydrophobization treatment

Li, Xiaolong; Qu, Zhong; Tang, Mingfang; Gao, Yafeng; Feng, Chi

doi:10.1016/j.cscm.2023.e02217

Cited by 1 publication

(8 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Rammed earth constructions, although having a history documented by evidence as far back as the Neolithic period, are still regarded with reluctance by some designers and builders as well as by some users [1,2]. Today, awareness of the need to reduce environmental impact, supported by current policies for sustainable development, is encouraging the construction industry to move towards the use of vernacular materials.…”

Section: Introductionmentioning

confidence: 99%

“…Today, awareness of the need to reduce environmental impact, supported by current policies for sustainable development, is encouraging the construction industry to move towards the use of vernacular materials. Of these, earth, especially clay, is particularly important because it responds to the three main sustainability objectives: social (through its broad accessibility, providing housing-around 40% of the population lives in earthen houses [1], and creating jobs for various population groups), economic (through generally affordable costs), and environmental impact (both through its low polluting impact and its high reusability-recycling). The performance of rammed earth walls in terms of heat storage capacity, heat transfer, thermal resistance, etc.…”

Section: Introductionmentioning

confidence: 99%

“…Allam et al report a thermal conductivity coefficient of 0.38-0.43 W/mK in the dry state and 0.55-0.62 W/mK in the wet state [12], and in contrast, Soudani et al report a thermal conductivity coefficient in the range of 0.6-2.4 W/mK [13], which demonstrates the large variation in this parameter depending on several factors, of which humidity, density, and site-specific composition are defining elements. The literature reports also indicate a thermal transmittance of 1.9-2.0 W/m 2 K [9] and a specific heat of about 1832 J/kgK [1,14]. Additionally, in the literature, there are reports of specific heat capacities of 664 J/kgK according to Li et al [1], 737 J/kgK according to Losini et al [10], and 917 J/kgK according to Jiang et al [15], in the range of 900-960 J/kgK confirmed by Cagnon et al and Giuffrida et al [14,16], or 750 J/kgK (dry state) and 1200 J/kgK (wet state) as presented by Allam et al [12].…”

Section: Introductionmentioning

confidence: 99%

“…The literature reports also indicate a thermal transmittance of 1.9-2.0 W/m 2 K [9] and a specific heat of about 1832 J/kgK [1,14]. Additionally, in the literature, there are reports of specific heat capacities of 664 J/kgK according to Li et al [1], 737 J/kgK according to Losini et al [10], and 917 J/kgK according to Jiang et al [15], in the range of 900-960 J/kgK confirmed by Cagnon et al and Giuffrida et al [14,16], or 750 J/kgK (dry state) and 1200 J/kgK (wet state) as presented by Allam et al [12].…”

Section: Introductionmentioning

confidence: 99%

“…Research indicates that the vapour diffusion resistance factor (µ) varies as a function of material density and compositional characteristics, with a maximum identified by Allison and Hall [33]. Li et al [1] report a coefficient of 0.031 kg/(m 2 s 0.5 ) for untreated rammed earth to increase hydrophobicity and 0.0062 kg/(m 2 s 0.5 ) for similar samples but treated with a SILRES ® BS 1802 hydrophobizer.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Thermophysical Characteristics of Clay for Efficient Rammed Earth Wall Construction

Petcu,

Dobrescu,

Dragomir

et al. 2023

Materials

View full text Add to dashboard Cite

This case study focuses on twelve compacted clay soil samples to understand their fundamental physical and thermal properties. For each sample, the density, thermal conductivity, thermal diffusivity, specific heat, and drying shrinkage were assessed. The identification and characterisation of the materials were also carried out by positioning them into the ternary diagram based on the percentage of sand, silt, and clay. These properties are definitive for the performance characteristics of materials used in rammed earth wall construction. The aim is to provide information for better knowledge and prediction regarding the dynamic heat flow in rammed earth walls. Experimental results show a relatively wide range of values for each property, reflecting the diverse properties of the sampled clays. The thermophysical characteristics of the 12 types of earth analysed showed correlations with reports in the literature in terms of density (1490–2150 kg/m3), porosity (23.22–39.99%), specific heat capacity (701–999 J/kgK), and thermal conductivity (0.523–1.209 W/mK), which indicates them as materials suitable for use in the construction of rammed earth walls. Using test data, a dynamic assessment of heat flow through simulated rammed earth walls was performed. For a better understanding of the results obtained, they were compared with results obtained for simulations where the building element would be made of concrete, i.e., a mineral wool core composite. Thus, heat flux at the wall surface and mass flux, respectively, during the 16 years of operation showed similar evolution for all 12 types of clay material analysed, with small variations explained by differences in thermophysical characteristics specific to each type of S1–S12 earth. In the case of walls made from clay material, there is a stabilisation in the evolution of the water content phenomenon by the 5th year of simulation. This contrasts with walls made of concrete, where the characteristic water content appears to evolve continuously over the 16-year period. Therefore, it can be said that in the case of the construction elements of existing buildings, which have already gone through a sufficient period for the maturation of the materials in their construction elements, the rammed earth wall quickly develops a moisture buffer function. In the case of simulating a mineral wool core composite wall, it cannot perform as a temperature or humidity buffer, exhibiting an enthalpy exchange with indoor air that is only 4% of that of the rammed earth walls; consequently, it does not play a significant role in regulating indoor comfort conditions. Overall, there is confirmation of the temperature and moisture buffering capabilities of rammed earth walls during both warm and cold periods of the year, which is consistent with other reports in the literature. The findings of this research provide a better insight into clay as a material for rammed earth walls for more efficient design and construction, offering potential improvements regarding indoor comfort, energy efficiency, and sustainability. The data also provides useful information in the fields of architecture and civil engineering regarding the use of clay as an eco-friendly building material. The results emphasise the importance of thoroughly understanding the thermophysical properties of clay to ensure the efficiency of rammed earth construction.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%