High Strength Fiber Composites for fabricating fire-resistant wood with improved mechanical properties

Abstract

This paper deals with one of the new research areas of Professor Hans Wolf Reinhardt, namely textile-reinforced structural members. Typically, wood is a light, versatile construction material well known for its ease of installation. The major drawbacks are its relatively low strength and stiffness, poor visco-elastic long-term deformation, and insufficient fire resistance. The results presented in this paper deal with the use of high modulus carbon / inorganic polymer composite skins to fabricate a sandwich plate that can be engineered to obtain high strength, high stiffness, and excellent fire resistance. The inorganic polymer is fire-resistant, can withstand 800°C indefinitely, and provides protection for both carbon fibers and the wood substrate. Sandwich plates were fabricated using balsa wood for applications that are weight-critical such as those in aerospace and naval structures. For applications in buildings, beams cut from typical woods such as oak were strengthened to improve their flexural strength and long-term deflection stability. The modulus of carbon fiber was 600 GPa and high stiffness values can be obtained with a very low reinforcement ratio. The strengthened beams were tested in flexure; while the fire resistance was evaluated, using the standard OSU (Ohio State University) heat release and NBS (National Bureau of Standards) smoke burner tests. The strengthened composite satisfied the high temperature (fire) requirements of the Federal Aviation Administration of the United States of America. This paper presents the flexural and high temperature response of the strengthened beams.