Raw earth historic and contemporary architectures are renowned for their good environmental properties of recyclability and low embodied energy along the production process. Earth massive walls are universally known to be able to regulate indoor thermal and hygroscopic conditions containing energy consumptions, creating comfortable interior spaces with a low carbon footprint. Therefore, earth buildings are de facto green buildings. As a result of this, some earthen technologies have been rediscovered and implemented to be adapted to the contemporary building production sector. Nevertheless, the diffusion of contemporary earthen architecture is decelerated by the lack of broadly accepted standards on its anti-seismic and thermal performance. Indeed, the former issue has been solved using high-tensile materials inside the walls or surface reinforcements on their sides to improve their flexural strength. The latter issue is related to the penalization of earth walls thermal behavior in current regulations, which tent to evaluate only the steady-state performance of building components, neglecting the benefit of heat storage and hygrothermal buffering effect provided by massive and porous envelopes as raw earth ones. In this paper, we show the results of a paper review concerning the hygrothermal performance of earthen materials for contemporary housing: great attention is given to the base materials which are used (inorganic soils, natural fibers, and mineral or recycled aggregates, chemical stabilizers), manufacturing procedures (when described), performed tests and final performances. Different earth techniques (adobe, cob, extruded bricks, rammed earth, compressed earth blocks, light earth) have been considered in order to highlight that earth material can act both as a conductive and insulating meterial depending on how it is implemented, adapting to several climate contests. The paper aims to summarize current progress in the improvement of thermal performance of raw earth traditional mixes, discuss the suitability of existing measurement protocols for hygroscopic and natural materials and provide guidance for further researches.

https://www.mdpi.com/2071-1050/11/19/5342/pdf

Hygrothermal Properties of Raw Earth Materials: A Literature Review

A novel concept of multiple deterministic analyses is proposed to design safer and more damage-tolerant structures for seismic excitation. The underlying risk is estimated to compare design alterna...

Intelligent Computational Schemes for Designing more Seismic Damage-Tolerant Structures

In the proposed paper, non-equilibrium and equilibrium models of heat and moisture transfer through wet building materials are presented and compared. In the former, the mass transfer between liquid and gaseous moisture results from the difference between the partial pressure of water vapor and its saturation value. In the second model, the equilibrium between both phases is assumed. In the non-equilibrium model, liquid moisture can be in the continuous (funicular) or discontinuous (pendular) form. The transfer of moisture for each proposed model is tightly coupled with the energy transfer, which is assumed to be an equilibrium process. The time step and grid size sensitivity analysis of both numerical models are performed primarily. The verification of the model is based also on the numerical data available in literature. Finally, obtained with considered models, temporal variations of moisture content in three locations in the computational domain are compared. Reasonable conformity of results is reported, and discrepancies related to differences in formulations of models are discussed.

https://www.mdpi.com/1996-1073/13/1/214/pdf

Analysis of Non-Equilibrium and Equilibrium Models of Heat and Moisture Transfer in a Wet Porous Building Material

Reproduction of traditional adobes using varying percentage contents of straw and sawdust

Study on the heat and moisture transfer characteristics of aerogel-enhanced foam concrete precast wall panels and the influence of building energy consumption

In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

Hygrothermal behavior for a clay brick wall

This paper studies the benefit of hybrid systems of earth retaining structures compared to using monotype systems in widening the roadsides to solve traffic congestion problems. Various innovative 2D finite element models including both monotype systems and hybrid systems were used to investigate the behavior of each system separately. The limit equilibrium approach for each system is considered the basic methodology in selecting the parameters used in the finite element analysis. The results are presented in terms of wall deformations, tensile forces in the reinforcements in case of using the soil-nailing wall or the mechanically stabilized earth retaining wall (MSE wall), anchor forces in case of using the anchored sheet pile wall, and the global factor of safety. Through the results of the analysis for each model, a comparison between monotype systems and hybrid systems of earth retaining structures has been done. It has been observed that using the hybrid cantilever/anchored sheet pile wall or using the hybrid MSE/anchored sheet pile wall has a significant effect in reducing the wall deformations and increasing the global factor of safety compared to using the full height monotype systems. In contrast, using the hybrid cantilever/soil-nailing wall or using the hybrid MSE/soil-nailing wall has no effect in reducing the wall deformations or in increasing the global factor of safety compared to using the full height monotype systems.

Comparison between monotype and hybrid earth retaining structures

Reliability Analysis of Piles in Multilayer Soil in Mooring Dolphin Structures

Negative skin friction developed on the pile surface causes many problems when piles are built in fully saturated clay. In this work, a study of NSF on a square cross-section pile corresponding to the circular pile circumference was developed. The pile was modeled as a concrete element, embedded and fully contacted with fully saturated soft clay. The clay layer is supported on a sand layer as a sub-base using ABAQUS software, and the NSF was developed on piles due to the consolidation of the clay over a 5-year period. A square pile has been found to provide lower NSF values than a round pile. Then, for the first investigation, both piles were loaded with lateral loads at the top to investigate the effect of the horizontal load on the NSF values, as there is no literature or study done on this point. The results emphasized that lateral loads reduce the NSF developed on piles. A parametric study was performed to investigate the parameters affecting the NSF values induced on piles, such as soil permeability, ballast, and lateral load values. It was concluded that square piles provide better NSF values than round piles for both single piles and pile groups. Doi: 10.28991/CEJ-2022-08-10-08 Full Text: PDF

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Mahmoud El-Meligy

Papers

Hygrothermal behavior for a clay brick wall

Comparison between monotype and hybrid earth retaining structures

Reliability Analysis of Piles in Multilayer Soil in Mooring Dolphin Structures

Study of Lateral Load Influence on Behaviour of Negative Skin Friction on Circular and Square Piles

An Improved Reliability Analysis Method for Mooring Dolphin Structures