Applications of Alginate in Geotechnical Engineering and Construction: A Review

Alginate, primarily sodium alginate, is a biopolymer derived from brown algae or bacterial sources that forms hydrogels via ionic crosslinking with certain divalent cations. Its incorporation into soils, earthen materials, cementitious composites, and asphalt mixtures improves mechanical performance and durability. This review collates recent advances in alginate-based treatments for geotechnical and construction applications, highlighting how alginate dosage, substrate type, gelation method, mixing strategy, and curing regime influence mechanical strength, physical properties, and self-healing efficiency. In soil stabilization, alginate treatments increase unconfined compressive strength (UCS) by 0.2–1.5 MPa in sand, with some studies reporting increases of over 2 MPa. Reported UCS improvements in alginate-treated clayey soils generally fall within the range of 50–150% compared to untreated samples, although isolated studies document increases exceeding 200%, depending on material composition and curing conditions. In cementitious systems, alginate-based capsules and hydrogels facilitate self-healing, achieving high closure rates of 70–100% for microcracks