The use of recycled bassanite and coal ash to enhance the strength of very soft clay in dry and wet environmental conditions

► Recycled bassanite and coal ash used as stabilizer materials for very soft clay. ► Recycled bassanite is produced from gypsum waste plasterboard. ► Strength and durability improved with the increase of bassanite and coal ash ratios. ► Wet-dry cycles has insignificant effect on mechanical properties and volume changes. ► Samples stabilized with bassanite and coal ash are durable against wet environment.