Abstract
Utilization of waste plasterboard as geomaterial solves a solid waste disposal problem, and also provides needed construction material. Waste disposal problems of waste plasterboard are becoming acute in the urban environment, because it is here that most waste plasterboard generating sites are located, and where the supply of natural construction aggregate is becoming scarce. Bassanite is produced by heating gypsum obtained from waste plasterboard, under conditions of 130°C or more. It is also environmentally friendly, due to its neutral nature. This paper presents the compaction properties and unconfined compressive strength of bassanite produced from waste plasterboard. Effect of bassanite additions on unconfined compacted soils is also investigated. The samples were compacted, and strengths determined by unconfined compression tests after 28 days of curing immediately after compaction. The optimum water content of bassanite-sand mixtures increases and the maximum dry density decreases with increase in bassanite content. The unconfined compressive strength of compacted bassanite-sand mixtures decreases linearly with increasing water content, irrespective of bassanite content. In contrast, the unconfined compressive strength of compacted bassanite-clay mixtures drops off sharply on the wet side of optimum water content, whereas on the dry side it increases with increasing water content, irrespective of bassanite content.
