Performance of the ASTM International E84, the standard test method for surface burning characteristics of building materials.
Photo Credit: Ashland Performance Materials

A material system and its assembly with good fire resistance performance will maintain thermo-mechanical stability under global fire exposure (full room involvement). It will allow the structure to maintain compartmentation when exposed to a global thermal insult. This helps both occupants trying to exit a burning building and firefighters suppressing the fire.

Fire regulations specify material system and assembly passive protection performance requirements based on application. In the context of FRP composites, we can consider these applications in a somewhat simplified form as interior skins, structural cores and exterior skin. Each application typically has different fire test requirements that are used to demonstrate performance. Fire regulations specify “pass/fail” limits for tests establishing performance requirements.

Using the Fire Testing Paradigm for Design

In general, there are four components to the fire testing paradigm: micro-scale, bench-scale, intermediate-scale and full-scale tests. Micro-scale tests are used by material suppliers to characterize their resins and additives. Bench-scale tests are used by suppliers and manufacturers to characterize materials system performance. Intermediate-scale tests are used by manufacturers to characterize assembly components. Full-scale tests are used by manufacturers to characterize assemblies.

Costs increase substantially from micro-scale and bench-scale tests to full-scale tests. Given that fire regulations rely heavily on intermediate-scale and full-scale tests, significant cost is involved in demonstrating the required performance. To minimize this cost, manufacturers need to understand how micro-scale and bench-scale fire tests can be used to predict results from intermediate-scale and full-scale tests.