Sustainability is defined as the process of developing and responsibly sustaining a healthy built environment based on resource-efficient and ecological principles. When it comes to sustainability, earthen construction is a good choice because of its minimal carbon impact and lower operating expenses. This study investigates the cost comparison between Alker and a reinforced concrete office with a dimension of 6 x 6 m. Alker is a stabilised form of earthen building. Based on the dry weight of the soil, it contains 10% gypsum, 2% lime, and 20%-22% water. Shredded plastic waste (SPW) was added to Alker to improve its properties with the addition of the environmental effect of plastic waste. The results showed that the office built with reinforced concrete had a total cost of Turkish Lira;119 348.57 (6630), whereas the building built with Alker materials had a total cost of Turkish Lira;103 474.19 (5748). Therefore, offices built with Alker's added SPW are 13% cheaper than offices built with reinforced concrete. Alker modified with shredded plastic waste has been demonstrated to be a sustainable building material with enhanced properties.

This study aims to optimize geotextile placement depth to enhance subgrade strength and achieve sustainable pavement design. Laboratory tests were conducted to characterize the soil and evaluate the effect of geotextile placement at depths of 3/4D, 1/2D, and 1/4D (where D is the total specimen depth). California bearing ratio (CBR) tests revealed that positioning the geotextile at 0.3D significantly improves subgrade strength, yielding a 78.08% increase in soaked CBR (from 5.84 to 10.4) and a 136.56% improvement in unsoaked conditions (from 3.72 to 8.8). Pavement analysis using IITPAVE software further demonstrated that geotextile placement at 0.3D effectively reduces fatigue and rutting strains, allowing reductions in pavement layer thicknesses-16.67% for bituminous concrete (BC) and dense bituminous macadam (DBM), 38.18% for water bound macadam (WBM), and 25% for granular sub-base (GSB). These optimizations lead to a cost saving of Indian Rupee36,06,610 ($42,430) per kilometer. The findings highlight the practical and economic benefits of placing geotextile at 0.3D depth (150 mm for a 500 mm subgrade), offering improved pavement performance, material savings, and enhanced sustainability. This research benefits pavement engineers, contractors, and transportation agencies by offering a sustainable, cost-efficient design strategy. Additionally, the findings provide a foundation for future research into geosynthetic reinforcement techniques under varying soil conditions, supporting the development of resilient, eco-friendly pavements.

Chemical stabilisation enhances strength and reduces the swell characteristic of expansive soils, and cement, lime and fly ash (FA) have been used as stabilisers. Currently, there is a scarcity of studies addressing the mix optimisation of expansive soil stabilised with cement, lime, and FA, considering factors such as strength, swell characteristics, cost, and emissions. Thus, the objective of this research is to develop an optimal mix for stabilising expansive soil using cement, lime, and FA, based on these parameters. The samples were stabilised with 2%-12% cement, 1%-6% lime and 5%-30% FA, and testing including unconfined compressive strength (UCS), swell pressure and California bearing ratio (CBR) were conducted. Utility analysis was undertaken by using Multi-Attribute Utility Theory (MAUT) incorporating UCS, cost/UCS, swell pressure, swell percent, and emissions as key parameters. The findings revealed that UCS of the cement stabilised samples increases with the cement content, while the optimum lime and FA contents based on UCS were 3% and 15% respectively. The swell pressure values of cement, lime and FA stabilised soils reduced by 11.6%-35.9%, 11.6%-22.8% and 45.0%-65.6%, respectively. Overall utility analysis revealed that 15% FA stabilised mix is the optimum mix in terms of strength, swell, cost, and emission.

Recycled concrete aggregates (RCA), derived from demolishing concrete buildings and pavements, have been treated with significant value as a recycled resource. Using RCA instead of virgin aggregates for pavement construction became a feasible approach to conserve construction trash resources since approximately 140 million tons per year were produced in the United States. This research conducted a life cycle cost analysis of stabilized clay subgrade soils in Kansas, USA, combining with RCA from pavements damaged by freeze-thawcycles and theD-cracks process. Class C fly ash and type II Portland cement were stabilizers for subgrade mixture designs. The performance of the mixtures was evaluated through Standard Proctor, unconfined compression strength (UCS), and California Bearing Ratio (CBR) tests. The full-depth flexible pavements incorporating these stabilized subgrades were designed using the AASHTOW are Pavement ME Design (PME) software. Results indicated that a 1:1 mix of Class C fly ash and type II Portland cement was the most effective stabilizer, decreasing the required thickness of the hot-mix asphalt (HMA) layer. The life cycle cost analysis demonstrated that the RCA-stabilized subgrades are economically viable when the chemical stabilizers are used in equal proportions.

Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and microstructural characteristics of weak Indian clayey soil partially substituted with lime (0-3.5%) and waste rubber tyre powder (0-15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the triaxial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly.

Using biopolymers for soil stabilization is favorable compared to more conventional methods because they are more environmentally friendly, cost-effective, and long-lasting. This study analyzes the physical properties of guar gum and laterite soil mixes. A comprehensive engineering study of guar gum-treated soil was conducted with the help of a brief experimental program. This study examined the effects of soil-guar gum interactions on the strengthening behavior of guar gum-treated soil mixtures using a series of laboratory tests. The treated laterite soil's dry density increased marginally, while its optimum moisture content decreased as the guar gum increased. Treatment with guar gum significantly enhanced the strength of laterite soil mixtures. For laterite soil with 2% guar gum, the unsoaked CBR increased by 148% and the soaked CBR increased by 192.36%. The cohesiveness and internal friction angle increased by 93.33% and 31.52%, respectively. These results show that using guar gum dramatically improves the strength of laterite soil, offering a more environmentally friendly and sustainable alternative to traditional soil additives. Using guar gum in T8 subgrade soil requires a 1395 mm pavement depth and costs INR 3.83 crores, 1.52 times more than laterite soil. For T9 subgrade soil, the depth was 1495 mm, costing INR 4.42 crores, 1.72 times more than laterite soil. This study introduces a novel approach to soil stabilization by employing guar gum, a biopolymer, to enhance the physical and mechanical properties of laterite soil. Furthermore, this study provides a detailed cost-benefit analysis for pavement applications, revealing the financial feasibility of using guar gum despite it requiring a marginally higher initial investment.

The present study aims to evaluate the possibility of perpetual pavement design with stabilized black cotton soil and polymer-modified bitumen for the major highways in India. Ground granulated blast slag (GGBS) was proposed as a potential material for use in pavements on weak subgrades, with proportions of 10%, 20%, 30%, and 40% added to the black cotton soil. Modified proctor compaction and California bearing ratio tests were conducted to determine the engineering properties of the soil and GGBS mixture. The study also aimed to design a high modulus bituminous concrete mixture for perpetual pavements using a combination of styrene-butadiene-styrene (SBS) polymer and viscosity grade 30 (VG 30) bitumen, with SBS added to the bitumen in amounts ranging from 1 to 4% by total weight. The physical and mechanical properties of both SBS-modified bitumen and neat bitumen were determined. Based on these results, 16 combinations of perpetual pavements were designed using the mechanistic-empirical methodology and according to Indian Road Congress (IRC 37: 2018) guidelines, with the aid of the IITPAVE software. These pavements included both treated and non-treated subgrades, as well as modified and unmodified mixes. The study found that the use of a sturdy foundation, treated subgrade, and high stiffness base materials is crucial in reducing the significant cost associated with using bitumen in a developing and oil-importing country like India. The designed pavements were also compared in terms of cost assessment and carbon dioxide emissions to determine the best option among the proposed combinations.

Conventional nondegradable packaging and mulch films, after reaching the end of their use, become a major source of waste and are primarily disposed of in landfills. Accumulation of non-degradable film residues in the soil leads to diminished soil fertility, reduced crop yield, and can potentially affect humans. Application of degradable films is still limited due to the high cost, poor mechanical, and gas barrier properties of current biobased synthetic polymers. In this respect, natural polysaccharides and proteins can offer potential solutions. Having versatile functional groups, three-dimensional network structures, biodegradability, ease of processing, and the potential for surface modifications make polysaccharides and proteins excellent candidates for quality films. Besides, their low-cost availability as industrial waste/byproducts makes them cost-effective alternatives. This review paper covers the performance properties, cost assessment, and in-depth analysis of macromolecular structures of some natural polysaccharides and proteins-based films that have great potential for packaging and mulch applications. Proper dissolution of biopolymers to improve molecular interactions and entanglement, and establishment of crosslinkages to form an ordered and cohesive polymeric structure can help to obtain films with good properties. Simple aqueous-based film formulation techniques and utilization of waste/byproducts can stimulate the adoption of affordable biobased films on a large-scale.