Sustainable Binary Blending for Low-Volume Roads-Reliability-Based Design Approach and Carbon Footprint Analysis

A state-of-the-art review on the application of lignosulfonate as a green alternative in soil stabilization

The utilization of lignosulfonate (LS) as a naturally derived biopolymer sourced from lignin in soil stabilization has gained significant attention in recent years. Its intermolecular interaction, hydrophobic and hydrophilic effects, adhesive and binding properties, erosion control abilities, compatibility with various soil types, and environmental sustainability make it a promising alternative to traditional soil stabilizers as well as highlighting its importance. By integrating LS into soil stabilization practices, soil properties can be enhanced, and an eco-friendlier approach can be adopted in the construction sector. This comprehensive review paper extensively examines the applications and structure of LS, as well as their efficacy and mechanisms on a micro-level scale. Afterward, it discusses the geotechnical characteristics of LS-treated soils, including consistency characteristics, dispersivity properties and erosion behavior, electrical conductivity, compaction parameters, permeability and hydraulic conductivity, compressibility characteristics, swelling potential, strength and stiffness properties, durability, and cyclic loading response. In general, LS incorporation into the soils could enhance the geotechnical properties. For instance, the Unconfined Compressive Strength (UCS) of fine-grained soils was observed to improve up to 105 %, while in the case of granular soils, the improvement can be as high as 450 %. This review also examines the economic and environmental efficiency, as well as challenges and ways forward related to LS stabilization. This can lead to economic and environmental benefits given the abundance of LS as a plant polymer for cleaner production and owing to its carbon neutrality and renewability.

Target reliability-based design optimization studies on cohesive soil amended with chitosan and casein for liner applications

The current study investigated the primary and secondary compressibility characteristics of organic clay with two biopolymers, Chitosan (Dch) and Casein (Dca) at dosages of 0.5%, 1%, 2%, and 4%. The primary compression index (Cc) values were reduced by 18% and 59% at dosage (Dch and Dca) of 4% at a consolidation pressure of 800 kPa. The secondary compression indices of chitosan and casein-treated soils fell below the normal range specified for organic soils and lay in the range of 0.01-0.017. The biopolymers also accelerated the consolidation process at all dosages (Dch) and 2% Dca. The hydraulic conductivity increased for all dosages of chitosan whereas it declined for all dosages of casein compared to untreated soil. The reliability analysis was conducted for biopolymer-treated soils and presented a rational approach toward the selection of a suitable liner. Chitosan failed to achieve a target reliability index of 3 whereas casein-amended samples attained values equal to and greater than 3 at all dosages and consolidation pressures at COV of Kmax = 20%. At all dosages, the casein-treated soils exhibited reliability index values greater than 3 up to COV of Kmax = 40% indicating the higher stability of casein mixes as a liner material.

Formulation of PG-FA-L composite modifier for repairing expansive soil based on the statistical mixed design method

The generation of large amounts of solid waste has led to exploration of solid waste-modified expansive soils; however, the effect of a single solid waste-modified expansive soil is not ideal. This study proposes a composite modification of expansive soils using a PG-FA-L system. Statistical analysis showed that the properties of the cured soil were significantly improved. PG and FA increased soil strength after a certain threshold, and L increased it at all stages. The presence of PG accelerated the volcanic ash reaction. Both PG and FA have a small effect on the swelling of the soil, whereas lime improves it significantly, but has a negative effect after a certain threshold. The 28-day unconfined compressive strength and deformation characteristics were used to derive the relevant regions for roadbed fill requirements and determine the optimum dosage.