A Critical Review and Research Framework for Stabilization of Collapsible Gypseous Soils

Gypseous collapsible soils fail through two coupled processes: wetting‐induced structural collapse and progressive dissolution of gypsum interparticle cement. The reviewed experimental datasets report untreated collapse potential (CP) values of 1.9%–22.3%. This review assesses six established treatment categories: traditional binders, geopolymers, biopolymers, nanomaterials, fiber reinforcement, and microbially induced carbonate precipitation (MICP), together with the unresolved MICP‐modified biochar research gap and proposed testing framework. The quantitative synthesis is descriptive and nonexhaustive. The first figure contains 20 untreated baseline CP measurements retained for the gypsum‐content comparison, the fourth figure presents 30 representative collapse‐related treatment‐response benchmarks, including 28 CP‐reduction values and two MICP strain‐reduction values, and the unconfined compressive strength (UCS) synthesis contains 15 treated observations. Several treatment categories report large CP reductions under laboratory conditions, but direct cross‐treatment ranking is not justified because collapse‐test method, response metric, soil condition, gypsum content, dosage, and curing differ among studies. Recent nanosilica studies extend the direct gypseous‐soil evidence to environmental cycling and model‐scale leaching, while biopolymer studies include leaching tests but remain limited in duration and field validation. MICP has direct laboratory evidence for reducing wetting‐related strain and improving hydraulic stability in gypseous soil, although this wetting‐strain and hydraulic‐response evidence is confined to one soil source. No published direct evaluation of the MICP‐modified biochar hybrid on gypseous soil was identified. A four‐phase experimental framework is therefore proposed to test this unresolved research gap.