Search Results (19)

This study demonstrates that compressive strength in cement-stabilized rammed earth is governed by conditional, threshold-controlled interactions rather than by intrinsic mineralogical effects. A B + K (beidellite + kaolinite) content exceeding 15% defines a low-strength regime (median ≈ 44.6 kN), whereas B + K ≤ 5% allows medians above 90 kN under 7% forming moisture. Quartz-rich fractions show a global correlation of r = 0.71. The Kruskal–Wallis test confirms strong clay grouping influence (H = 72.78, p < 0.001). Analysis of the experimental dataset shows that most strength distributions deviate from normality, invalidating pooled parametric inference and justifying the use of distribution-free methods. At the global level, bulk density and quartz-rich fractions are the dominant positive contributors to strength. Meanwhile, forming moisture and high combined beidellite–kaolinite content (>15%) exerts a negative influence under elevated forming moisture (8%), whereas the effect of 1:1 and 2:1 clay minerals differs depending on their hydro-affinity and moisture regime. However, subgroup analyses reveal frequent reversals in both magnitude and sign of correlations, proving that mineral effects depend critically on cement dosage and moisture regime, revealing discrete strength regimes defined by hierarchical interactions between moisture, cement content, and mineralogical thresholds. The combined beidellite–kaolinite content was classified into ≤5%, 5–15%, and >15% groups. Specimens with B + K > 15% consistently formed a low-strength regime, with a median destructive load of approximately 44.6 kN (≈1.1–1.3 MPa depending on cross-sectional area). In contrast, mixtures with B + K ≤ 5% achieved median loads above 90 kN (≈2.5–3.0 MPa). Quartz-rich fractions showed a strong global positive correlation with strength (r = 0.71), while the grouped clay fraction exhibited a highly significant effect (Kruskal–Wallis H = 72.78, p < 0.001). A regime shift was observed between 7% and 8% forming moisture, where quartz correlation changed from strongly positive (r ≈ 0.70) to negative (r ≈ −0.69). Increasing cement content from 6% to 9% significantly improved strength (H = 12.30, p = 0.0005), although this effect diminished when B + K exceeded 15% or forming moisture reached 8%. Association rules further confirm that high or low strength emerges only from specific multivariate combinations. The results show that mineralogy influences CSRE strength primarily through interaction with technological parameters, providing a robust basis for regime-based interpretation and rational mixture design. Full article

This study aims to evaluate the potential of circular economy principles in earth-based construction using an experimental rammed earth building located in Pasłęk, Poland as a case study. The research focuses on end-of-life scenarios for earth materials, with particular emphasis on rammed earth, adobe, and compressed earth blocks stabilized with Portland cement. A scenario-based life-cycle assessment (LCA) was conducted to compare alternative demolition and reuse strategies, including manual and mechanical deconstruction, as well as on-site and off-site material reuse. Greenhouse gas emissions associated with demolition (Module C1) and transport (Module C2) were estimated for each scenario. The results indicate that manual deconstruction combined with local, on-site reuse leads to the lowest carbon footprint, whereas off-site reuse involving long-distance transport significantly increases greenhouse gas emissions. In addition, qualitative reuse pathways were identified for wood, glass, ceramics, and insulation materials. The study reveals a lack of standardized technical procedures for the recovery and reuse of stabilized earthen materials after demolition and highlights the importance of integrating end-of-life planning into the early design phase using digital tools such as material passports and BIM. The findings demonstrate that properly designed rammed earth systems can provide a viable low-tech solution for reducing construction waste and supporting circular material flows in the built environment. Full article

This study evaluated the influence of soil preparation method and initial moisture content on the compressive strength of cement-stabilized rammed earth (CSRE). Cube samples stabilized with 7–12% cement were compacted using a manual rammer, cured for up to 28 days, and tested according to adapted EN 12390-3 procedures. These results indicated that eliminating the powdering step improved laboratory efficiency and produced specimens more representative of field practice. These findings demonstrate that labor-intensive powdering of natural soils is unnecessary, provided that moisture is accurately determined, thereby improving both laboratory efficiency and consistency with field practice. The outcomes contribute to optimizing laboratory methodologies for earthen construction materials. Full article

In this investigation, different natural by-products were used to modify the Particle Size Distribution (PSD) of a soil to evaluate their potential in Stabilized Rammed Earth (SRE) building. Three different mixes were manufactured: (i) a mix composed entirely of a clayey soil, (ii) a mix consisting of mining by-products and clayey soil and (iii) a mix entirely based on mining by-products. Unstabilized and stabilized samples of the mixes were manufactured using two cement dosages (2.5% and 5%), and the samples were tested for Unconfined Compressive Strength (UCS), soaked UCS, and wetting and drying tests. Mining by-products demonstrated significant potential in SRE building, as their addition to the clayey soil resulted in higher UCS values compared to the UCS obtained from clayey soil alone. Unstabilized samples lost their integrity during exposure to water. The inclusion of mining by-products also showed potential as, although the mixes did not fully meet the requirements for soaked UCS and the wetting and drying tests, the mix containing both mining by-products and clayey soil retained its integrity in water, unlike the samples composed solely of clayey soil. M3C5 successfully met the requirements for soaked UCS and the wetting and drying tests, further highlighting the great potential of mining by-products in SRE building. Full article

Rammed earth (RE), despite being an ancient method of construction, has smoothly integrated into contemporary civil engineering due to its compatibility with current sustainability requirements for housing structures. However, typical RE needs some improvements to fully realize its potential as both a structurally effective and environmentally friendly building technique. As a result, multiple bio-inspired enhancement methods have been suggested to substitute traditional cement or lime stabilizers. This review examines the various efforts made in the past decade to biologically stabilize natural soil for the construction of RE. It provides a brief overview of the different bio-based materials utilized in this area but primarily concentrates on their effects on the mechanical strength and water durability of RE structures. The review also addresses current obstacles that prevent the widespread industrial adoption of this valuable earth-building method and identifies potential directions for future research. Overall, the available literature on the mechanical performance and durability of bio-based rammed earth (BRE) shows encouraging outcomes. Nonetheless, various issues, such as the absence of thorough data on the discussed topics, issues related to the inherent properties of soil and biomaterials, and doubts regarding the reliability of durability evaluation methods, have been identified as factors that could lead to a lack of confidence among RE practitioners in adopting bio-based treatments. This study will provide a solid foundation for future researchers aiming to advance BRE technology, thus enhancing sustainability within the construction sector. Full article

Construction using earth materials demonstrates ecological sustainability using locally sourced natural materials and environmentally friendly demolition methods. In this study, the environmental impact of adding cement to soil materials for rammed earth farmhouse construction in rural China was investigated and comparatively simulated using the One Click LCA database, focusing on the conflict between sustainability objectives and the practical aspects of cement addition. By analyzing how the addition of cement aligns with local construction practices and addressing the debate surrounding the inclusion of cement in rammed-earth construction, our objective is to provide insights into achieving a balance between the environmental impact and the pragmatic considerations of using cement in earthen building practices. Three local structure scenarios are evaluated via simulations: cement-stabilized rammed earth wall, fired brick wall, and a localized reinforced concrete frame structure. The quantitative environmental impacts are assessed, and the qualitative differences in adaptation, economic sustainability, and other factors are examined in the context of present-day development in rural China. The results show that the use of cement-stabilized rammed earth wall-supported structures is associated with higher embodied carbon emissions compared to structures supported by reinforced concrete frames and enclosed by brick walls; however, these emissions are lower than those for brick wall-supported structures while effectively meeting the structural requirements. In addition, the use of cement-stabilized earth for perimeter walls simplifies material management and disposal throughout the building’s life cycle, and the cost-effectiveness of cement has been found to be substantially greater than that of reinforced concrete frames and brick structures, improving economic viability and social acceptability, especially among low-income communities in rural areas Full article

Rammed earth blocks have recently gained substantial popularity in construction materials due to their environmental benefits, energy saving, and financial effectiveness. These benefits are even more pronounced if waste materials such as olive waste ash (OWA) are incorporated in rammed earth blocks. There is limited information on the use of OWA in rammed earth blocks. This paper investigates the use of OWA and cement in improving rammed earth block characteristics. OWA was incorporated to partially replace the soil by 10, 20, 30 and 40% of its weight and cement was added in percentages of 2, 4, 6 and 8% by the dry weight of the composite soil. Proctor, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) tests were performed at 7, 28, and 56 days. Results indicated that OWA inclusion decreased the maximum dry density while it increased the optimum moisture content. However, cement addition improved the maximum dry density of soil. The UCS results revealed that OWA possessed cementitious and pozzolanic behavior, and soil mechanical properties improved by up to 30% due to OWA inclusion, after which there was a significant drop of 40%. The trend in the CBR results was similar to those of UCS. To further clarify the experimental results, a mathematical model was proposed to determine the variation in strength as a function of time. Furthermore, correlations between soil mechanical properties were conducted. Predicted equations were developed to determine the properties of rammed earth block. All in all, the inclusion of OWA in cement stabilized earth block suggests the potential to improve the properties of rammed earth blocks. Full article

Cement-stabilized rammed earth (CSRE) is a variation of the traditional rammed earth building material, which has been used since ancient times, strengthened by the addition of a stabilizer in the form of Portland cement. This article compares the compressive strength of CSRE determined from specimens cored from structural walls and those molded in the laboratory. Both types of specimens underwent a 120-day curing period. The tests were conducted on specimens with various grain sizes and cement content. An analysis of variance (ANOVA) was performed on the obtained results to determine whether it is possible to establish a conversion factor between the compressive strength values obtained from laboratory-molded cubic samples and those from cored samples extracted from the CSRE structure. The study revealed that the compressive strength of CSRE increases significantly over the curing period, with substantial strength gains observed up to 120 days. The results indicated no statistically significant difference in the mean unconfined compressive strength (UCS) between cubic and cored specimens for certain mixtures, suggesting that a shape coefficient factor may not be necessary for calculating CSRE compressive strength in laboratory settings. However, for other mixtures, normal distribution was not confirmed. These findings have implications for the standardization and practical application of CSRE in construction, highlighting the need for longer curing periods to achieve optimal strength and the potential to simplify testing protocols. Full article

Earth structures have a significant sustainable impact on regulating indoor environmental qualities. Yet, using soil materials can lead to fungal growth, impacting occupant health and structural stability. This study investigates the susceptibility of earth-based construction materials with cement, limestone, and acrylic-based additives to fungal growth. Laboratory tests were conducted on mixtures under conditions found in inhabited buildings in hot–arid regions. The proposed methodology was based on a 7-week artificial incubation of fungi obtained from moldy walls through regulating the room temperature to fall between 18 °C and 19 °C and a controlled humidity level of around 45%. These conditions were adopted according to the readings monitored in typical buildings in the study area. The results showed that fungal growth was evident on the surface of mixtures, including higher percentages of soil and lower percentages of additives. Mixtures comprising 50% soil, 15% acrylic-based additive, 15% quicklime, and 20% cement supported the least fungal growth, presenting the best choice as a sustainable, efficient replacement. Visual observation followed by microscopic examination ensured the results. Furthermore, results of an environmental post-occupancy evaluation of a constructed rammed earth building using the optimized mixture showed no signs of fungal proliferation on the inner walls afterward. Full article

This paper investigates the viability of using a commercially available liquid polymer (LP) in lieu of ordinary cement to stabilize soil during rammed earth (RE) construction. The scope of this study includes modifying and testing the locally available natural soil with two different LPs at various percentages. Once the optimum moisture content (OMC) of the soil with LPs was determined using the Proctor test, test samples were prepared by chemical and mechanical stabilizations. Following the curing process in an unconfined open-air laboratory environment for 7 days, soil samples were tested to determine the unconfined compressive strength (UCS) and California bearing ratio (CBR) values. The results demonstrate that the lubrication effect of polymers is different than that of water. The first polymer type yields a lower OMC compared to water, while the second polymer achieves a higher OMC. The CBR and UCS values of polymer-stabilized soils are improved for both polymer types at all dosages. The CBR values of polymer-modified soils showed as high as a 10-times improvement compared to Portland cement (PC) stabilization. A similar trend is observed for the UCS results as well. The UCS value of polymer-stabilized soils reached over 1900 psi (13 MPa), which was over 3-times higher than the UCS of PC-stabilized soil. Full article

This study aims to check the compatibility of a selection of waste and recycled biopolymers for rammed earth applications in order to replace the more common cement-based stabilization. Five formulations of stabilized rammed earth were prepared with different biopolymers: lignin sulfonate, tannin, sheep wool fibers, citrus pomace and grape-seed flour. The microstructure of the different formulations was characterized by investigating the interactions between earth and stabilizers through mercury intrusion porosimetry (MIP), nitrogen soprtion isotherm, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The unconfined compressive strength (UCS) was also evaluated for all stabilized specimens. Three out of five biopolymers were considered suitable as rammed earth stabilizers. The use of wool increased the UCS by 6%, probably thanks to the combined effect of the length of the fibers and the roughness of their surfaces, which gives a contribution in binding clay particles higher than citrus and grape-seed flour. Lignin sulfonate and tannin increased the UCS by 38% and 13%, respectively, suggesting the additives’ ability to fill pores, coat soil grains and form aggregates; this capability is confirmed by the reduction in the specific surface area and the pore volume in the nano- and micropore zones. Full article

This paper aims to test the deterioration of cement stabilized rammed earth and consider its characteristics during its lifespan in various exposure conditions. Both visual and mechanical properties were tested to determine the impact of long-term exposure to natural weather conditions. Cemented stabilized rammed earth is a variation of the traditional rammed earth building material which has been used since ancient history and is strengthened by the addition of stabilizers in the form of Portland cement. This article analyzes the long-term properties of wall panels made of this material, which were subjected to varying exposure conditions for five years. After this period, compression tests of specimens cut from panels stored in various environmental conditions were carried out. Based on the results and visual properties of the specimens, long-term changes in unconfined compressive strength were observed and primary durability attributes were described. Despite minimal visible wear to the external layers of the wall panels, the natural weather conditions proved to deteriorate material strength characteristics, especially on specimens with high cement content. No correlation between visual characteristics and compressive strength measures were found. The present study is vital in adequately describing cement stabilized rammed earth behavior in natural weather conditions typical of a humid continental climate. Full article

The article aims to determine the effect of cement addition on the water vapour resistance factor of stabilized rammed earth. Literature analysis indicates that different earthen materials show large differences in water vapour resistance factor values. The high diffusion resistance of concrete concerning other construction materials suggests that cement will be one of the factors significantly affecting these values. The paper presents water vapour resistance factor test results of rammed earth with various soil particle sizes and cement contents. The obtained results showed that an increase of cement addition increases the diffusion resistance of the material. However, the diffusion resistance of cement stabilized rammed earth is still low compared to concrete. Full article

The main advantage of the structural composite material known as cement-stabilized rammed earth (CSRE) is that it can be formulated as a sustainable and cost-saving solution. The use of the aggregates collected very close to a construction site allows economizing on transportation costs. Another factor that makes sustainability higher and the costs lower is a small addition of cement to the CSRE in comparison to the regular concrete. However, the low cement content makes the compressive strength of this structural material sensitive to other factors. One of them is the composition of the aggregates. Considering the fact that they are obtained locally, without full laboratory control of their composition, achieving the required compressive strength of CSRE is a challenge. To assess the possibility of achieving a certain compressive strength of CSRE, based on its core properties, the innovative algorithm of designing CSRE is proposed. Based on 582 crash-test of CSRE samples of different composition and compaction levels, along with the use of association analysis, the spreadsheet application is created. Applying the algorithm and the spreadsheet, it is possible to design the composition of CSRE with high confidence of achieving the required compressive strength. The algorithm considers a random character of aggregates locally collected and proposes multiple possible ways of increasing the confidence. They are verified through innovatively applied association analyses in the enclosed spreadsheet. Full article

Cement-stabilized rammed earth (CSRE) is a sustainable construction material. The use of it allows for economizing on the cost of a structure. These two properties of CSRE are based on the fact that the soil used for the rammed mixture is usually dug close to the construction site, so it has random characteristics. That is the reason for the lack of widely accepted prescriptions for CSRE mixture, which could ascertain high enough compressive strength. Therefore, assessing which components of CSRE have the highest impact on its compressive strength becomes an important issue. There are three machine learning regression tools, i.e., artificial neural networks, decision tree, and random forest, used for predicting the compressive strength based on the relative content of CSRE composites (clay, silt, sand, gravel, cement, and water content). The database consisted of 434 samples of CSRE, which were prepared and crushed for testing purposes. Relatively low prediction errors of aforementioned models allowed for the use of explainable artificial intelligence tools (drop-out loss, mean squared error reduction, accumulated local effect) to rank the influence of the ingredients on the dependent variable—the compressive strength. Consistent results from all above-mentioned methods are discussed and compared to some statistical analysis of selected features. This innovative approach, helpful in designing the construction material is a solid base for reliable conclusions. Full article