ABSTRACT Gypsum has been one of the most widely used since ancient times. Gypsum wallboard consists mainly of gypsum, i.e. calcium sulfate dihydrate, CasO4�2H2O. In buildings, the chemical, mechanical and thermal properties of gypsum wallboard play an important role in delaying the spread of fire. This fire resistance property is mainly attributed to the absorption of energy related with the loss of hydrate water going from the dihydrate (CaSO4�2H2O) form to the hemihydrate (CaSO4��H2O) and from the hemihydrate to the anhydrous form (CaSO4) in a second decomposition. The present paper is a comparative study of commercially available standard, fire-rated type X and type C gypsum wallboards. Type X wallboards are typically reinforced with non-combustible fibers so as to protect the integrity of the wallboard during thermal shrinkage while the type C wallboards are incorporated with more glass fibers and an additive, usually a form of vermiculite. These type C wallboards have a shrinkage adjusting element that expands during the process of thermal shrinkage. Differential scanning calorimetry (DSC), thermogravimetric analysis�mass spectroscopy (TGA-MS), thermomechanical analysis (TMA), scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) were used to characterize and compare the materials. Various properties such as the heat flow, weight loss, gases evolved, dimensional changes and crystalline structures of the gypsum wallboards were studied using these instruments. The results of these tests will be presentedKeywords: gypsum, Calcium Sulfate; dehydration; thermal shrinkage; thermal decomposition.

Comparative studies on fire-rated and standard gypsum wallboard

247th National Meeting (2014)

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