Mechanical behavior of fire-resistant biocomposite

Biocomposites are typically formed by binding natural fibers derived from plants or cellulose using organic binders. The fibers that are used are normally industrial by-products and, hence, they are abundant and inexpensive. One such material is sawdust, and varieties of composite boards are being manufactured utilizing sawdust as filler material. Two major drawbacks of this system are their vulnerability to fire and very low bending strength. Both the matrix and the sawdust are flammable and this paper deals with using an inorganic matrix to improve the fire resistance. The inorganic matrix can resist temperatures up to 1000 degrees C and it provides protection to sawdust for short durations. The strength of these boards was increased by reinforcing with a very low percentage of high strength glass and carbon fibers. Since these fibers provide up to a fifteen-fold increase in strength, the cost increase is justifiable. Prisms were made using various proportions of sawdust ranging from about 11% to 38% by mass. The prisms were tested in compression and flexure to obtain the basic mechanical properties and determine the optimal sawdust content. Prisms with optimal sawdust content were also strengthened with glass or carbon fiber reinforcements to increase flexural capacity. The results indicate that it is possible to manufacture and engineer these types of composite beams to obtain a specified strength without using any specialized equipment, heat, or pressure, thus, producing an environmentally conscious biocomposite material. (C) 2008 Elsevier Ltd. All rights reserved.