Earth Blocks Research Articles

Influence of rubber aggregates from the recycled tires on the physico-mechanical and durability properties of compressed earth blocks

To meet sustainable development goals, global policies are strongly oriented toward valorizing alternative resources such as local materials and waste from different sectors of activity. This study aims to evaluate the influence of adding rubber aggregates from used/recycled tires (GPU) on the physico-mechanical and durability properties of compressed earth bricks (CEB). The CEB were made with an earthen matrix containing 8% cement, and 0 to 2% mass of GPU. The CEB were cured under ambient conditions (30±5°C) for 28 days. The results showed a real improvement in physical and mechanical performance and durability indicators of CEB with increasing GPU content. The apparent density changed slightly from 1697 kg/m3 to 1733 kg/m3. Total water absorption decreased from 21% to 19% with a slight decrease in water-accessible porosity from 35.7% to 33.1%. The capillary absorption coefficient at 10 minutes also decreased from 14 g/cm2.min1/2 to 10 g/cm2.min1/2 The increase of 29% was noted on the compressive strength in the dry state ranging from 3.5 to 4.5 MPa and of 60% on the compressive strength in the wet state ranging from 1.1 MPa to 1.7 MPa. This resulted in the improvement of the structural efficiency coefficient by 27% ranging from 2080 to 2651 Pa.m3/kg. Abrasion resistance coefficient increased more than 50% ranging from 10.8 to 16.9 cm2/g. By comparing the results to the normative references, the CEB containing GPU can be classified as CEB usable in load-bearing walls in a dry environment and resistant to abrasion.

Evaluation of the incorporation of artisanal lime into the composition of stabilized earth blocks

This study evaluates the incorporation of artisanal lime into the composition of Stabilized Earth Blocks (SEB) to enhance local materials and minimize the use of cement. The objective is to develop a sustainable approach that utilizes available resources while meeting construction needs. The physico-mechanical behavior of the SEB was examined through a mixed chemical stabilization method (cement/lime), gradually replacing cement with artisanal lime. The main parameters analyzed include the replacement rate and the nature of the stabilizer, allowing for an in-depth understanding of the effects of this integration. The results indicate that replacing 12.5% of the cement with artisanal lime improves the long-term physico-mechanical properties of the SEB, particularly in terms of density, absorption, porosity, as well as compressive and flexural strength. Furthermore, this approach supports the transition towards more environmentally friendly construction practices. Additionally, the study includes a comparison of the results obtained using industrial lime, thus reinforcing the relevance of using lime in construction.

Thermo-mechanical behavior of compressed earth blocks (CEB) stabilized and reinforced with fibers

Thermo-mechanical behavior of compressed earth blocks (CEB) stabilized and reinforced with fibers

Recovery and Restructuring of Fine and Coarse Soil Fractions as Earthen Construction Materials

Excessive consumption of natural resources to meet the growing demands of building and infrastructure projects has put enormous stress on these resources. On the other hand, a significant quantity of soil is excavated for development activities across the globe and is usually treated as waste material. This study explores the potential of excavated soils in the Brittany region of France for its reuse as earthen construction materials. Characterization of soil recovered from building sites was carried out to classify the soils and observe their suitability for earthen construction materials. These characteristics include mainly Atterberg limits, granulometry, organic matter and optimum moisture content. Soil samples were separated into fine and coarse particles through wet sieving. The percentage of fines (particles smaller than 0.063 mm) in studied soil samples range from 28% to 65%. The methylene blue value (MBV) for Lorient, Bruz and Polama soils is 1, 1.2 and 1.2 g/100 g, and French classification (Guide de terrassements des remblais et des couches de forme; GTR) of soil samples is A1, B5 and A1, respectively. The washing of soils with lower fine content helps to recover excellent-quality sand and gravel, which are a useful and precious resource. However, residual fine particles are a waste material. In this study, three soil formulations were used for manufacturing earth blocks. These formulations include raw soil, fines and restructured soil. In restructured soil, a fine fraction of soil smaller than 0.063 mm was mixed with 15% recycled sand. Restructuring of soil fine particles helps to improve soil matrix composition and suitability for earth bricks. Compressed-earth blocks of 4 × 4 × 16 cm were manufactured at a laboratory scale for flexural strength testing by using optimum molding moisture content and compaction through Proctor normal energy. Compressive strength tests were performed on cubic blocks of size 4 × 4 × 4 cm. Mechanical testing of bricks showed that bricks with raw soil had higher resistance with a maximum of 3.4 MPa for Lorient soil. Removal of coarse particles from soil decreased the strength of bricks considerably. Restructuring of fines with recycled sand improves their granular skeleton and increases the compressive strength and durability of bricks.

Acoustic performances of earthen walls, review of modeling approaches and tools

Earth construction benefits of a renewed interest particularly for environmental reasons. However, due to its mainly artisanal construction process, acoustic characterization data of earthen walls are quite rare which can limit their use for projects involving acoustic requirements. Moreover, the great diversity in materials as well as in related construction techniques could result in a large spread in terms of acoustical performances. In this context, acoustic characterizations and modelings are necessary to provide a better understanding on earth materials behaviors. In this study, the results from different modeling approaches are compared to few earth walls sound transmission loss data publicly available. The modeling tools including simplified formulas or more elaborated softwares present different levels of complexities and assumptions sometimes highlighting the specificities of this material. Depending on the construction techniques used (earth blocks, light earth, earth panels etc ...), different assumptions can be appropriate. Extrapolations of performances on several walls for both sound transmission loss and sound absorption provide information regarding tendencies and potentially achievable performances for future earth construction projects. Nevertheless, the comparison between the modeling approaches allows gaining insight on the limits of some approaches and the necessary critical analysis before a possible generalization to other earth walls.

Development of Water Repellent Polish for the Pointing and Finishing on NBRRI Earth Block Walls

Assessment of the challenges facing the adoption and promotion of NBRRI CSEBs reviewed the issues of instability or erosion of the brick wall surfaces, a case study reveals that it is a common problem to all walls made of this block within different zones of the country. The quest to proffer sustainable solution to these challenges necessitated this research work. The study aimed at producing a locally sourced water repellent polish for painting and finishing on NBRRI earth block walls. A substance (slurry) that can resist moisture penetration into adobe walls through the surfaces. The materials used were sourced from the rainforest zone of the country, investigated and tried with different mix ration depending on the Oxide composition in phases. The first phase featured the following materials and equipment; limestone, crab soil, periwinkle shell, Termite mould, natural clay, Hydrated lime (Ca (OH)2, Soluble Rubber (Top Bond) and Distilled water for mixing. Equipment includes; Weighing balance of 0.1g accuracy, sieve no 2020 (75pm) stirring rod, brushes and spray. In this phase soluble rubber was tried differently with the materials in various oxide composition applied on the existing CSEB walling unit, from observation some performed well while others performed moderately. The second and the third phase of the trial employed limestone and hydrated lime (Ca (OH)2 as the main stabilizer to activate reaction between the combination of any of the samples that contained high silica and a certain percentage of aluminium oxide (Al2CO3) x H2O(c) to produce an effective result as the Ca (H2O(s)) react in the presence of air to give Ca2SiO3(s) a solid that is stable in water, and applied on CSEB wall surfaces for observation across wet and dry Season.

Compressive Strength Characteristics of Compressed Stabilized Earth Block (CSEB) Units and Walls

This paper is mainly focused on compressive strength behavior of Compressed Stabilized Earth Block (CSEB) units and CSEB walls. Compressed Stabilized Earth Block (CSEB) is a rectangular block used in wall construction. The ingredients of CSEB are soil, cement, fine aggregate, crusher dust, and a small amount of water. These blocks have less energy consumption and carbon emission, and they provide improved thermal insulation. In addition, they use local resources and disseminate appealing aesthetics with elegant profile and uniform size. Due to these advantages CSEB can be used as a green construction material. This research aims to study the strength characteristics of CSEB wall in compression and evaluate the suitability of CSEB walls as load bearing walls in structures. This research studies physical and mechanical characteristics of CSEB units made from red residual soil of Lele (Lalitpur) with 8% cement for stabilization. This paper discusses the compressive strength behavior of walls constructed of size 0.660m x 1.100m x 0.220m using CSEB units in cement sand mortar and stabilized mud mortar separately which were tested after 28 days. The experimental values after laboratory testing of CSEB masonry wall with height to thickness ratio 5:1 for cement sand mortar (1:6) and stabilized mud mortar (stabilized with 8% cement and 16% extra sand) separately are compared with relevant values from different codes. Results obtained from compressive strength tests of masonry walls constructed in the laboratory and those values from different codes concerning the strength of masonry unit and mortar are compared and found to be in agreement. The comparison of laboratory results with codal provisions of design of masonry walls illustrate that CSEB masonry walls can be designed in the similar way as brick masonry walls.

Prediction of moisture content of cement-stabilized earth blocks using soil characteristics, cement content, and ultrasonic pulse velocity

This article investigates the importance of moisture content in cement-stabilized earth blocks (CSEBs) and explores methods for their prediction using machine learning. A key aspect of the research is the development of accurate moisture content prediction models. The study compares the performance of various machine learning models, and XGBoost emerges as the most promising model, demonstrating superior accuracy in predicting moisture content based on factors like soil properties, cement content, and ultrasonic pulse velocity (UPV). The study employs SHAP (SHapley Additive exPlanations) to understand how these features influence the model’s predictions. UPV is the most significant factor affecting predicted moisture content, followed by cement content and soil properties like uniformity coefficient. Also, the study explores the possibility of using a reduced set of features for moisture content prediction. They demonstrate that a combination of UPV, cement content, and uniformity coefficient can achieve good accuracy, highlighting the potential for practical applications where obtaining all data points might be challenging.

Predicting compressed earth blocks compressive strength by means of machine learning models

Compressed Earth Blocks (CEB) are an interesting alternative to conventional masonry units. They are unfired and provide a thermal comfort in the constructions. However, their compressive strength needs to be assessed to ensure a mechanical stability. The latter depends on the soil variability, as well as several manufacturing parameters such as water content, compaction pressure, stabilizer type and proportion. This is challenging as it requires time and effort to adapt the parameters to achieve satisfactory results. In this study, machine learning classification models were trained using historical data for predicting CEB compressive strength. Voting Classifier (VC) provided the highest performance with an accuracy of 78 %. SHapley Additive exPlanations (SHAP) were used to identify and prioritize the features in the model's decision-making process. The compaction pressure and soil granularity were the most decisive parameters. VC was also tested to assess the compressive strength of sediment-based CEB manufactured at the laboratory scale.

Physico-mechanical Characterization of Stabilized Earth Blocks with Snail Shell and Termite Mound Powders as Pozzolanic Binders

The aim of this study is to reduce the reliance on cement in the construction of Stabilized Earth Blocks (SEBs) by assessing the addition of snail shell and termite mound powders as a partial substitute for cement. The focus of this study is on the valorization of local materials and animal waste in sustainable construction. Laterite, used as the base material, was stabilized by substituting 0 to 80% of the cement with snail shell and termite mound powders to create blocks that were tested for their mechanical strength and water absorption. The results show that the compressive strength of the blocks remains above the required threshold of 4 MPa up to a 50% substitution, with a downward trend at higher rates. The capillary water absorption of the stabilized earth blocks remains within the limits of blocks classified as low-absorption, with coefficients ranging from 0.58 kg/m²/min at a 50% substitution to 1.14 kg/m²/min at an 80% substitution. These findings suggest that a substitution up to 50% could represent an adequate balance between mechanical performance and environmental benefits, thus ensuring the required durability and mechanical strength. Although the research is limited to the study of these materials in their raw state, future work could explore the enhancement of the pozzolanic activity of snail shell and termite mound ash through treatments such as calcination to further strengthen the eco-efficiency of the process.

Valorization of Fired Clay Bricks Debris (grog) Using Egg Shell and Coconut Shell in the Synthesis of an Ecological Compressed Earth Blocks: Microstructure and Engineering Properties

The aim of this work is to valorize fired clay brick debris (grog, CH) by using egg and coconut shells in the production of eco-friendly compressed earth bricks for sustainable building materials. Samples were cured at ambient temperature (23 ± 3 °C) and obtained by altering different percentages of (CO) and (CN) at 13%, 26% and 40%, respectively; while another mix design of calcined eggshell and coconut shell were incorporated together into the grog powder. Some comprehensive physico-mechanical properties such as water absorption (WA), bulk density (BD), apparent porosity (AP), moisture content (MC), compressive strength (σ) and elastic modulus (EM) were carried out. Chemical composition, X-ray diffraction (XRD) analysis, Fourier Transformed Infra-red (FT-IR), Energy Dispersive X-ray (EDX) analysis and Scanning Electron Microscopy (SEM) were studied. Results show an increase in compressive strength with increasing percentages of calcined eggshell, from 87CH 13CO, 74CH 26CO, 60CH 40CO as 1.38, 2.70, 3.88 MPa, respectively. For 87CH 13CN, 74CH 26CN, 60CH 40CN coconut shell addition show an increase in the percentages of compressive strength. The bulk density decreases with the increase in percentages of calcined eggshell and coconut shell and the percentage of grog decrease. Linear correlation equtions between mechanical properties and mix proportion were determined. SEM micrograph shows a dense microstructure with an agglomeration on the structure. Results obtained indicates an improvement in the engineering properties due to the addition of eggshell waste and these improved properties are suitable to enhance sustainable eco-friendly building materials.

Influence of the Addition of Palm (Borassus Aethiopum Mart.) Fibers on the Durability of Compressed Earth Blocks

This study aims to determine the influence of the content and length of the palm (borassus aethiopum mart.) fibers on the physical, mechanical and thermal properties of Compressed Earth Blocks (CEB). Three fiber contents (0.2%, 0.4% and 0.8%) of different lengths (10 mm, 20 mm, or 40 mm) were used to make CEB. CEB with 0% fiber content were manufactured to serve as control samples. CEB specimens stabilized with palm fibers or not were subjected to various tests according to standard XP P 13-901 for the determination of the following properties: dry density, water absorption, dry compressive strength, abrasion resistance and thermal conductivity. The results show that the dry density of CEB decreases from 4% to 7% when the content and length of the fibers increase respectively from 0.2% and 10 mm in length to 0.8% and 40 mm in length. The water absorption of fiber-containing CEBs ranges from 14% to 22% with increasing fiber content and length. The results also indicate that the mechanical and thermal properties are improved for well-chosen fiber contents. Thus, the dry compressive strength of the fibers increases by more than 13% for a fiber content of 0.2% and a length of 10 mm compared to CEB with 0% fibers. On the other hand, the optimal abrasion resistance values are obtained for a fiber content of 0.4% and a length of 40 mm. For all CEBs, the thermal conductivity values vary from 0.51 W/mK to 0.38 W/mK when the fiber content varies from 0.2% to 0.8%. Overall, palm fiber content has a greater influence on the measured physical, mechanical and thermal characteristics than fiber length.

Thermal Performance of Clay and Millet Waste Compressed Earth Blocks Stabilized with Cement

As a contribution of the building sector to mitigating the effects of climate change, namely rising sea levels, floods, droughts, cyclones, sandstorms, retreat of arable land and forest fires, in anticipation of the objectives of the Paris Agreement, on the one hand, and energy efficiency on the other hand and the development of sustainable and environmentally friendly building materials, this paper presents the thermal characterization of compressed earth blocks using two clays used by the population of MARADI in Niger for the construction of habitats. The clays are mixed with sand (10%), cement (4%) and varying proportions of millet waste from 0% to 10%. The study shows that the thermal conductivity of composites decreases as the amount of millet waste increases. Conversely, the thermal resistance increases with each addition. Conductivity values varies from 0.268 W. m<sup>−1</sup>.K<sup>−1</sup> to 0.644 W. m<sup>−1</sup>.K<sup>−1</sup> for MARADAWA clay (BAM) samples and from 0.275 W. m<sup>−1</sup>.K<sup>−1</sup> to 0.723 W. m<sup>−1</sup>.K<sup>−1</sup> for Jiratawa clay (BAJ) samples. This represents a reduction of 61.96% for Jiratawa clay and 58.39% for MARADAWA clay compared to non-added materials. Composite materials are more effective in terms of thermal insulation.

Assessing acoustic performance of building material: A finite element model for 3D printed multilayer micro-perforated panels with compressed earth blocks

This study deals with 3D printing multilayered micro-perforated panels (M-MPPs) coupled with buildings materials as compressed earth block for noise reduction applications. The sound absorption coefficient α is utilized as a metric to assess the sound insulation capabilities across a frequency range spanning from 10 to 3000 Hz, then evaluated and validated by numerical and experimental methods. The FEM model developed makes it possible to predict the acoustic absorption of M-MPPs by tuning the frequency range and varying optimized acoustics parameters, considering hole-hole interaction and taking into account visco-thermal effects that are present in compressed earth blocks. It is shown that the shape of perforations and material properties including the porosity rate, arrangement in the design of multilayer micro-perforated structures are identified to play a significant role in the sound performance of the entire structure. In addition, the application of MPP coupled with compressed earth blocks improve the sound absorption capacity of the composite structure. The developed FEM leads to accurate prediction of performance, efficient optimization, and cost effectiveness. Finally, the present study reveals the importance of M-MPPs combined with compressed earth blocks (CEBs) as viable noise reduction materials, particularly relevant for engineering applications and development initiatives in emerging economies.

Investigation of the mechanical effects of coconut coir reinforcement on Compressed Stabilized Earth Blocks

Investigation of the mechanical effects of coconut coir reinforcement on Compressed Stabilized Earth Blocks

Alkali-activated limestone powder and groundnut shell ash based geopolymer for stabilizing earth blocks

Alkali-activated limestone powder and groundnut shell ash based geopolymer for stabilizing earth blocks

Eco-recycled cement's effect on the microstructure and hygroscopic behaviour of compressed stabilised earth blocks

Recycled cement (RCP) retrieved from old cement waste aims to replace carbon-intensive ordinary Portland cement (OPC) in earth stabilisation, improving the mechanical performance and durability of earth construction, without significantly compromising its ecological character and thermophysical properties. This study analyses the microstructure and hygroscopic behaviour of compressed earth blocks (CEB) stabilised with RC. In addition, soil was partially replaced with construction and demolition waste (CDW) to further improve the CEB sustainability. To this end, the sorption-desorption isothermal behaviour of CEB with different soils, types and contents of stabiliser (0–10 % RCP or OPC), and varying percentage replacements of OPC with RCP (20, 50, 100 %) or soil with CDW (0, 15, 25 %) was analysed and related to their microstructure, which was characterised in terms of scanning electron microscopy, mercury intrusion porosimetry and nitrogen adsorption analysis. Unstabilised and OPC CEB were considered for comparison purposes. The microstructure of CEB was refined after RCP stabilisation, which influenced their hygroscopicity and adsorption-desorption hysteresis. Depending on the clay content of the soil, stabilisation reduced or increased the hygroscopic capacity of CEB. After stabilisation, the water adsorption decreased up to 25 % in CEB with clayey soil and increased up to 22 % in CEB with sandy soil. However, the hygroscopic behaviour was not significantly affected by the type of stabiliser. The substitution of OPC with RCP increased the volume of water adsorption up to 3 %, due to its slightly finer porosity. RCP has proven to be effective as an earth stabiliser, leading to CEB with adsorption-desorption properties similar to those of OPC CEB.

A Comparison of Conventional Blocks and Stabilized Earth Blocks as Building Materials in Uganda

A Comparison of Conventional Blocks and Stabilized Earth Blocks as Building Materials in Uganda

Proposed mix design improvements of compressed stabilized earth blocks (CSEB) with particle packing optimization and coir reinforcement

Proposed mix design improvements of compressed stabilized earth blocks (CSEB) with particle packing optimization and coir reinforcement

Feasibility and Application of Local Closed-Loop Materials to Produce Compressed and Stabilized Earth Blocks.

The validation of a feasible application for the production of sustainable bricks with local materials in humid and hot climates, which would allow the current housing needs of a constantly growing population with scarce economic resources to be met while also reducing energy inputs for climate control, is a current challenge without a definitive solution. Therefore, this research studied the incorporation of local aggregates and two second-generation materials to produce lime-stabilized Compressed Earth Blocks (CSEBs) using a semi-automatic machine for their manufacture. An initial matrix was designed as a baseline, and three more were developed with variations to incorporate second-generation materials individually and as mixtures. The stabilizer was added in concentrations of 5, 10, and 15%, resulting in a total of 12 batches of CSEBs. Eleven of the studied batches exceed the normative limits for simple compressive strength and initial water absorption coefficient. The best result of simple compressive strength was obtained in two batches of the same matrix that used construction demolition waste (CDW), reaching 4.3 MPa (43% above the minimum limit established by the most restrictive regulations and 115% above the least restrictive). It was possible to produce sustainable bricks in situ with average ambient temperatures of 32 °C and relative humidity of 91%.