The production of agricultural residues causes environmental pollution, especially in regions with intensive horticultural production. The solution is to maximise the use of residues, applying the 'zero waste' model and using them to develop construction materials. Natural fibres used to reinforce materials have environmental and economic benefits due to their low cost. This research presents an innovative characterisation using an inverted-plate optical microscope, a high-resolution scanning electron microscope (HRSEM) and a 3D X-ray microscope. A physico-mechanical and chemical characterisation of horticultural fibres was also conducted. The fibres analysed were those produced in the highest quantities, including those from tomatoes, peppers, zucchinis, cucumbers and aubergines. The viability of these natural fibres for use as reinforcements in biocomposites was investigated. The analysis centred on studying the microstructure, porosity, chemical composition, tensile strength, water absorption and environmental degradation of the natural fibres. The results showed a porosity ranging from 47.44% to 61.18%, which contributes to the lightness of the materials. Cucumber stems have a higher tensile strength than the other stems, with an average value of 19.83 MPa. The SEM analysis showed a similar chemical composition of the scanned fibres. Finally, the life cycle of the materials made from horticultural residue was analysed, and negative GWP (global warming potential) CO2eq values were obtained for two of the proposed materials, such as stabilised soil reinforced with agricultural fibres and insulation panels made of agricultural fibres.

The feasibility of lightweight construction materials by incorporating a waste that is difficult to recycle, based on waste from intensive agriculture: vegetable fibers and propylene, is presented. This innovative material consists of a mixture of Alhambra Formation soil (Granada, SE of Spain) reinforced with vegetable fibres from tomato, pepper, zucchini, cucumber, aubergine and polypropylene fibres. The fibres were used in the mixture at a ratio of 2.5%, 5.0%, 7.5% and 10.0%. These values were then compared with control test samples that did not contain any residues. The compatibility of the fibres with the soil of the Alhambra Formation was then evaluated in terms of its physical-mechanical properties, specifically in relation to uniaxial compression and longitudinal deformation. Due to the highly hygroscopic nature of plant fibres, their absorption was measured and the techniques of presoaking and non-soaking the fibres before mixing them with the soil of the Alhambra Formation were investigated. The results of the unconfined compression tests show that the increase in fibre volume leads to a significant decrease in compressive strength. The highest compressive strength from a residue ratio >= 7.5 % was achieved with the cucumber residue and the non-pre-soaking technique. This residue ratio reached an average value of 1.82 MPa, which is 4% lower than the reference specimen without additives. Notwithstanding the decline in mechanical strength with elevated residue quantities, the resulting Alhambra Formation soil composite blended with a 7.5 % cucumber ratio may be regarded as a prospective candidate for implementation using the Projected Earth System technique.

This study contributes to the understanding of the vernacular raw-earth heritage of the Champagne region in France, where such structures are currently being documented. The research investigates the mineral composition, grain size distribution, and physico-chemical, mechanical, thermal, and hydric properties of seven adobe types derived from soils with varying compositions (predominantly silicate or limestone-based soils). In particular, the influence of calcite content, which spans a wide range from 0 % to 84.9 %, was examined. The results indicate a strong dependency of peak compressive strength on calcite content: higher CaCO3 levels correspond to lower peak compressive strength. Additionally, the study reveals that the metal oxide content of soils is a critical factor directly associated with mechanical performance. Interestingly, it was observed that historical builders often used weaker adobes for load-bearing purposes and stronger ones for filling, likely without adherence to formal construction standards. Rather than compressive strength, wall design appears to have played a more critical role in structural stability. Regarding thermal properties, calcite content showed minimal influence on diffusivity, specific heat capacity, and thermal conductivity across all adobe samples. Furthermore, all adobes demonstrated excellent to very good moisture regulation performance, with corresponding Moisture Buffer Values varying from 1.65 to 3.09 g/(m2.%RH). The findings of this study underscore the potential of traditional raw-earth techniques in rediscovering and evaluating earthen architecture, with implications for promoting sustainable and environmentally friendly contemporary earthen construction and renovation practices.

Modern construction is largely dependent on steel and concrete, with natural materials such as earth being significantly underutilised. Despite its sustainability and accessibility, earth is not being used to its full potential in developed countries. This study explores innovative building materials using Alhambra Formation soil (Granada, Spain) reinforced with difficult-to-recycle agricultural waste: polypropylene fibres contaminated with organic matter and leachates. Fibres were added at a ratio between 0.20 and 0.80% of the soil mass, leachates at a ratio between 4.25 and 8.50%, and lime was incorporated at 2.00% and 4.00% for specimens with higher residue content. Physico-mechanical properties, including uniaxial compressive strength and longitudinal strain, were analysed together with the microstructure. The results showed that polypropylene fibres, in comparison to the use of leachates, improved compressive strength and ductility, reaching a compressive strength of 1.76 MPa with a fibre content of 0.40%. On the other hand, this value is 7.4% lower than the reference sample without additives. The fibre-reinforced samples showed a higher porosity compared to the samples with leachates or without additives. This approach highlights the potential of agricultural waste for the development of sustainable construction materials, offering enhancements in the strength and ductility of reinforced soils.

Conventional practices in earth construction, such as cement stabilization and the energyintensive firing of bricks, contribute significantly to carbon emissions due to the processes involved in cement production and kiln operation. Additionally, concerns over the low strength of earth-based materials have limited their broader applications. This research addresses these challenges by implementing ultra-high pressures (200 MPa and 400 MPa) and bio-binders (animal glue and xanthan gum) to enhance earth materials for construction. Unstabilized earth mixture and normal pressure case (20 MPa) are also included in this study for comparison. A customdesigned mold and a specialized production process are developed to fabricate cylindrical earth samples for testing. After undergoing three hours of consolidation and 28 days of curing, unconfined compressive strengths are measured. Scanning electron microscopy is used to investigate the influence of ultra-high pressures and bio-binders on the microstructures of compressed earth blocks. The experimental results demonstrate that animal-glue- and xanthan-gumstabilized samples under ultra-high pressure achieve compressive strengths comparable to traditional fired bricks, while unstabilized samples exhibit the strength of cement-stabilized rammed earth. This research demonstrates that ultra-compression combined with bio-binder stabilization presents a viable strategy for reducing the carbon footprint of earth construction while significantly enhancing the mechanical properties.

The importance of physical, chemical, and mineralogical properties in selecting soils stabilized by activated natural pozzolan (ANP) was demonstrated. Five soil banks were identified, and two were selected: B1Z due to its SiO2 content and the presence of Montmorillonite and B3M for its granulometry and plasticity. Electrical con- ductivity (EC) was measured to monitor reactivity by testing two stabilizers, ANP and lime. Soils with 2.5% ANP exhibited higher EC than those with 10% lime. Compressive strength (CS) was analyzed. Soils with 10% ANP recorded higher CS than those with lime. Chemical and mineralogical properties were more relevant than physical ones in selecting soils stabilized through ANP.

Tropical regions like French Guiana need local building materials to cope with high population growth and the high cost of imported cementitious materials. Poured earthen construction could represent a local, cost-effective, and ecologically friendly alternative. To ensure good workability and facilitate pouring, the use of dispersants to deflocculate clay particles is an effective strategy that reduces water demand and increases the material's density and strength. Natural organic dispersants can replace industrial ones while reducing costs and carbon footprint. It is currently unknown how organic dispersants could improve the workability, physical and mechanical properties of the iron-rich lateritic soils present in French Guiana. Here, different potential dispersants were evaluated at constant water content on a lateritic soil-based mortar: citric acid, sodium carbonate, tannins, tannins+sodium hydroxide (tannins+NaOH), tannins+sodium carbonate (tannins+Na2CO3). These dispersants were compared to industrial sodium hexametaphosphate (NaHMP). Three types of tannins were tested: hydrolyzable tannins from oak and chestnut, and condensed tannins from acacia. This study shows that all formulations improved workability and mechanical strength but only tannins+NaOH or Na2CO3 had a strong dispersant effect comparable to NaHMP. Furthermore, tannins+NaOH or Na2CO3 decreased the mortar's density without impacting strength, which may result from reactions between the soil's iron oxides and tannins, as observed by infrared spectroscopy (FTIR). Altogether, these results show that the addition of organic dispersant is an appropriate strategy to improve the fresh and hardened properties of lateritic soils. Particularly, tannins combined with sodium carbonate may represent an eco-friendly dispersant for poured earth in regions with iron-rich lateritic soils.

As a significant symbol of human civilization advancement, earth construction not only inherits traditional architectural culture but also enjoys worldwide popularity and widespread usage throughout China due to its economic and environmentally friendly nature, as well as its moisture absorption and heat storage advantages. Consequently, earth construction has garnered considerable attention from international scholars. This paper compiles relevant data to review the developmental trajectory of earth construction, while conducting an in-depth analysis of the performance characteristics of earthen materials. Furthermore, it provides a comprehensive overview of the impact of three modification methods on the mechanical and durability properties of earthen materials, along with a discussion on the research concerning the thermal and moisture performance of these materials. Simultaneously, discussions were held on the relevant research findings and potential directions for the development of earthen materials. Finally, conclusions were drawn, suggesting a comprehensive utilization of their thermal and moisture performance, emphasizing the enhancement of their mechanical and durability performance. Additionally, attention was urged towards the economic and ecological aspects during the construction and maintenance phases of earth construction. These recommendations aim to facilitate the sustainable development and widespread application of earthen materials in the future.