The construction industry faces significant challenges, including the urgent need to minimize environmental impact and develop more efficient building methods. Additive manufacturing, commonly known as 3D-printing, has emerged as a promising solution due to its advantages, such as rapid fabrication, design flexibility, cost reduction, and enhanced safety. This technology enables the creation of structures from digital models through automated layering, presenting opportunities for mass production with innovative materials and architectural designs. This article focuses on developing eco-friendly earthen-based materials stabilized with 9 % cement and 2 % rice husk (RH) for large-scale 3D-printed construction. The raw materials were characterized using geotechnical tests for soil, water absorption tests for natural fibers, and SEM-EDS to examine their microstructure and elemental composition. Key properties such as rheology, printability (pumpability and extrudability), buildability, and compressive strength were evaluated to ensure the material's optimal performance in both fresh and hardened states. By utilizing locally sourced materials such as soil and rice husk, the mixture significantly reduces environmental impact and production costs, making it a sustainable alternative for large-scale 3D-printed construction. The material was integrated into architectural and digital fabrication techniques to construct a bioinspired housing prototype showcases the practical application of the developed material, demonstrating its scalability, adaptability, and suitability for innovative and costeffective real housing solutions. The article highlights the feasibility of using earthen-based materials for sustainable 3D-printed housing, thereby opening new possibilities for advancing greener construction practices in the future.

Several studies focus on enhancing soil strength through the incorporation of natural or synthetic fibers. However, there is limited published data on the effectiveness of rice husk in soil reinforcement. The use of rice husk as a reinforcing material is supported by the fact that rice is one of the most produced and consumed cereals globally. In this article, we analyze the behavior of a clayey soil from southern Brazil with the addition of 0.5, 0.75, and 1% rice husk (RH), comparing it to coconut coir (CC) and curau & aacute; fibers (CU). In unconfined compressive strength tests (UCS), increases in soil strength of 20, 40, and 140% were observed for RH, CC, and CU, respectively, compared to pure soil. From consolidated undrained triaxial compression tests, both unreinforced soil and soil reinforced with 1% RH, CC, and CU were examined. The triaxial tests revealed an increase in the internal friction angle of 72 and 98%, alongside a decrease in cohesion of 57 and 94% due to the addition of CC and CU, respectively, in terms of effective stress. In contrast, RH did not significantly enhance the soil's behavior, likely due to its shorter fiber length.

Bio-mediated ground improvement techniques, including Microbial Induced Calcite Precipitation (MICP) and Enzyme Induced Calcite Precipitation (EICP) treatment methods, are extensively being employed nowadays in a variety of construction projects as newly emerging sustainable and environmentally-friendly approaches to enhance the mechanical properties and durability characteristics of earthen composites. The intrinsic brittleness of MICP- and EICP-treated soils, however, considerably limits their applications in practical geotechnical engineering. Fiber reinforcement has been widely acknowledged as an efficient solution to overcome such challenges and augment the ductility of biologically stabilized soils. Accordingly, there is growing attention to integrating natural and synthetic fibers into bio-based composites, opening up exciting possibilities for improved performance and versatility in different civil engineering applications. This review aims to examine the current state of research on utilizing fiber additives to enhance the effectiveness of MICP and EICP treatment methods in an attempt to provide an in-depth insight into the effects of fiber type, content, and length as well as the underlying mechanisms of fiber interactions within the porous structure of such treated soils. The applications of fiberreinforced bio-cemented soils, their limitations, and the major challenges encountered in practice, as well as the potential areas of interest for future research and the key factors to be considered when selecting suitable fiber for optimal soil treatment using MICP/EICP, are all critically elaborated and discussed. By synthesizing the current research findings, the study provides engineers with a valuable resource to guide the development and optimization of fiber-reinforced MICP and EICP techniques for effective soil improvement and stabilization. Based on the findings of all relevant studies in the literature, a comprehensive cost-performance-balance analysis is conducted aiming to serve as a useful guideline for researchers and practitioners interested in applying fibers in various construction projects or other related applications where either MICP or EICP technique is being utilized as the main soil stabilization approach.

In the effort to mitigate environmental pollution there is a growing global demand for sustainable materials in place of existing synthetic one. In this research work, stacked hybrid laminate composite were produced by combining alkali treated kenaf and bamboo natural fiber mats as reinforcement with a biopolymer polylactic acid as matrix through compression moulding technique. The current work intends to study the outcome of surface modification of natural fibers which modifies their performance characteristics. Here the overall characteristics: mechanical, tribological, thermal and physical properties were investigated for the fabricated sample and the assessments were made between the alkali treated and untreated fiber composites. The alkali treated samples exhibited an enhanced tensile strength of 44.83 %, flexural strength of 108.13 %, compressive strength of 86.21 % and peak degradation temperature compared to the untreated samples. In addition, the tribological characteristics of the treated hybrid composites were studied. The inherent hydrophilic characteristics of natural fiber which leads to water absorption is resisted by the chemical treatment and it is also confirmed by the Fourier Transform Infrared (FTIR) analysis.Morphological analysis of the fractured and worn composites was also conducted to examine the microstructural changes and interface bonding within the developed composites. The biodegradability of the developed composites under soil burial test showed that the untreated composites exhibited higher weight loss percentage compared to the treated samples. The experimental results reveal that the alkali chemical treatment significantly enhances the suitability and compatibility of kenaf and bamboo natural fibers in polymer composites for sustainable construction products like roofing sheets and door panels in rural terrain regions.

Millions of tonnes of bagasse are annually generated as waste from the sugar industry, the disposal of which poses a critical global challenge. To address this, the study explores the potential utilization of sugarcane bagasse fibers as a reinforcing material to sand, aiming to enhance its mechanical properties through laboratory investigations. Initially, the primary physical characteristics of both sand and bagasse fibers are examined using laboratory tests and scanning electron microscopy. Further, consolidated drained triaxial compression tests were carried out on sand specimens, with fiber contents varying from 0 to 2%. The investigations encompass the influence of fiber content, fiber length, and effective confining pressures on the strength parameters, dilation, and stiffness of reinforced sand. Upon shearing, the bagasse reinforced sands exhibited a strain-softening behavior at low fiber contents and a strain hardening behavior at higher fiber contents. Results indicate the beneficial utilization of bagasse fiber in enhancing the strength parameters, and reducing the residual strength loss of sand, sensitive to the effective confining stress. With increase in percentage of bagasse fiber, the dilation of sand was found to be decreasing. The inclusion of bagasse fibers also leads to a reduction in the initial and secant stiffness of the sand. Furthermore, as the length of fiber shortens at same percentage of fiber, the peak and critical angle of friction reduces. Based on the test results, a normalized model of the reinforced sand has been developed to capture the peak and residual states of the sand in correlation with different critical parameters.

In this research, Aloe Vera Gel (AVG) was incorporated into Unsaturated Polyester Resin (UPR) with jute-cotton union fabric to fabricate partially biodegradable composites. These composites were fabricated using a hand lay-up technique and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry Analysis (TGA), thermal conductivity measurements, water absorption tests, degradation assessments, cracking tests, and Universal Testing Machine (UTM) analysis. The study found that increasing the percentage of AVG in the composites led to a decrease in thermal conductivity, indicating improved insulation properties. Samples reinforced with AVG showed enhanced resistance to damage from iron nails, with reduced scratching and fiber displacement observed. However, the addition of AVG resulted in decreased thermal, mechanical, and water resistance properties compared to composites without AVG. FTIR analysis demonstrated interactions between AVG and the matrix materials. In degradation tests, composites subjected to an alkali environment (PH = 11.96) showed the highest weight reduction (2.22 %) compared to those without AVG. Similarly, composites buried in soil exhibited greater weight loss (2.38 %) than their counterparts lacking AVG. Overall, the developed composite's reduced heat transfer rate suggests its potential application as an insulating material in environments such as rural poultry housing and the automotive industry.

Reinforcement of soils with fibers generally increases the mechanical properties of the fiber-reinforced soil (FRS) system. However, published literature is limited to investigating the undrained response of clay and synthetic fibers, with few studies targeting natural clay and natural fibers under drained conditions. There is a need to study the response of fiber-reinforced clay systems under drained conditions to assess long-term stability. This paper investigated the drained shear strength and durability of clays reinforced with natural hemp fibers using isotropically consolidated drained triaxial tests, in which the fiber content, confining pressure, and compaction water content were varied. Results showed that the incorporation of hemp fibers improved the deviatoric stress at failure by up to 60%, which increased the drained cohesion and friction angle of the FRS by 7-10 kPa and 3-7 degrees, respectively. The increase in cohesive intercept was not affected by the compaction water content, while the increase in friction angle was pronounced in specimens compacted at optimum water content (w = 18%). Durability tests showed that the improvement in strength due to hemp fibers diminishes after 3 weeks of curing prior to drained testing, indicating the dramatic negative impact of degradation of natural fibers on the mechanical performance of fiber-reinforced clay and the need for industrial treatment of the fiber.

Underprivileged people in many parts of Asia, Africa, Europe, and Latin America use earthen dwellings because of environmental and economic advantages. However, such non-engineered structures often encounter unacceptable risks from various natural calamities such as earthquakes, floods, etc. The 3rd January 2017 moderate earthquake in Tripura (NE India) is prime evidence of severe damage to earthen houses in rural Tripura. The present research focuses on enhancing the seismic strength of traditional earthen houses through mechanical stabilization with locally available low-cost sustainable natural fibers (i.e., jute and straw) and stabilizing materials (i.e., clay and lime), respectively. Primarily, the shear and flexural strength of both stabilized and unstabilized model rammed earthen wallettes are investigated experimentally. Thereafter, a 3D finite element (FE) numerical model is developed to verify the sanctity of the experimental findings. The study reveals that fiber-reinforced earthen wallettes, especially jute fiber-reinforced wallettes, exhibited significant improvement in shear and flexural strength including ductility behaviour whereas, clay and lime-stabilized wallettes offered improvement in strength exhibiting brittle failure. Finally, the seismic response of a prototype fiber-reinforced rammed earth wall is evaluated through 3D FE-based numerical modelling considering the input motion of the 2017 Tripura earthquake which also indicated significant improvement compared to the unimproved one. However, from the viewpoint of sustainability, it is concluded that carbon emissions of approx. 38% may be reduced in the case of natural fibers such as jute and straw compared to synthetic stabilizing agents (i.e., lime). Hence, the study promotes the use of low-cost sustainable fibers with a lower carbon footprint and minimum energy consumption in earthen houses.