ABSTRACT
Strategies were devised for development of inorganic binders with moderate levels of moisture resistance using primarily natural raw materials subjected to simple processing methods. The raw materials considered here included gypsum, lime, citric acid and soda ash. In this binder, gypsum and calcite (resulting from carbonation of lime) provide binding effects, and the presence of calcite provides improved moisture resistance when compared with gypsum used alone. Citric acid is used in this formulation as a set retarder that also favourably affects the crystalline structure of gypsum. The binder system was prepared by blending the raw materials in different proportions, which was then mixed with sand and water, placed at room temperature and 50% relative humidity, and subjected to early-age compression test in air-dried and saturated conditions. Promising formulations were further evaluated using the SEM, EDX and XRD techniques. The results verified partial achievement of the targeted compositions at an early age.
