Microstructure and Materials Science of Fire Resistive Materials

Fire resistive materials (FRMs) are a critical component in the design of safe buildings. Current performance testing is strongly based on the ability of the FRM to adhere to and to control the temperature rise of its substrate. A fundamental understanding of the microstructure and performance properties of these materials is sorely needed to model their performance in real world systems and scenarios. While room temperature properties are more easily evaluated, it is the high temperature properties of the materials that are critical to performance during an actual fire. This paper will describe preliminary efforts in an experimental/computer modeling program being conducted at NIST to apply a materials science approach to characterizing the microstructure and properties of these materials. Three-dimensional x-ray microtomography is applied to obtain a representation of the microstructure of the materials. These microstructures can then be analyzed quantitatively to characterize critical parameters such as porosity and pore sizes, and the effects of these parameters on properties such as thermal conductivity. This analysis, along with characterization of the density and heat capacity of the FRM as a function of temperature, will provide the inputs needed for thermal performance models.