Design And Production Of Ceiling Board Using Plaster Of Paris (pop) Gypsum Material

2.8    CHEMICAL PROPERTIES OF GYPSUM
Gypsum is a mineral found in sedimentary rock formation in a crystalline form known as calcium sulfate dehydrate (CaS04.2H20). One hundred pounds of gypsum rock contains approximately 21 pounds (or 10 quarts) of mined or quarried and transported to the manufacturing facility.
2.9    SURVEY ON HEMP CORE FIBER AS USED FOR CONSTRUCTION PURPOSE
Hemp core fiber used in the production of this project is a agricultural waste which is obtain from cannabis sativa L. serves as a reinforcement material. The use of agricultural wastes as reinforcement of composite materials is one of the most important targets in today’s materials research (Ahankari et al., 2011; Ashori and Nourbakhsh, 2010; Rabiet al., 2009). The present research is concerned with the use of the wastes from the industrial hemp, Cannabis Sativa L., to obtain useful cellulose fibers to manufacture fiber-plaster products for ceiling.
    Industrial hemp is one of the crops having a highest yield among those of temperate zones, being at the same time one of and less intensive ones. It is highly self-compatible what means that it requires crop rotation. Similar to other lignocellulosic fibers, hemp is biodegradable and environmentally friendly (Mutje et al., 2007). This, together with its high strength and durability and low density, explains the increase in the use of hemp fibers in the manufacture of composite materials (Carver, 1941; Hayo and van der Werf, 2004).
    The use of cellulose fibers as reinforcing agents in composite building materials offers many advantages over glass fibers, such as the possibility to manufacture products with low density and good biodegradability (Joshi et al., 2004; Li et al., 2006; Mwaikambo and Ansell, 2003). However, cellulose fibers also have some disadvantages, for instance, they present low modulus of elasticity, high moisture absorption, they decompose in alkaline environments and are susceptible to biological attack, and they have variable mechanical and physical properties (Swamy, 1990).
 Some of these disadvantages could be overcome using fibers from hemp core with a higher durability than the traditional cellulose fibers from pine and with a specific tensile strength of 0.750 GPa, and specific modulus of elasticity of 60 GPa. These properties make hemp fibers a candidate material with potential as reinforcement fiber (Li et al.,2004).
Many authors have studied the use of hemp fibers as reinforcement for building materials (Dalmay et al., 2010;Placet, 2009; Sedan et al., 2008;Troedec et al., 2011).