Performance of Intumescent Fire Protection Coatings in Non-Standard Heating Scenarios

Background Theory: Use and Types of Intumescent Coatings

Intumescent coatings are a form of passive fire protection commonly used in the construction industry to increase the fire resistance of structural members, by up to one to three hours, as required by the structural fire design codes. They are principally applied to structural elements that typically loose performance during a fire such as steel, wood and aluminium structures.

This research programme will focus on structural steel protection coatings specifically intumescent coatings. The purpose of the intumescent coating is to insulate the steel and hence delay/prevent the steel from reaching critical temperatures (500-550°C) and, by extension, prevents failure/collapse (Bailey, 2010). The subsequent increase in fire resistance will allow occupants adequate time to evacuate and "buys time" for rescue services (Grand, 2000).

There are three main types of Intumescent Coatings:

  • Solvent-based
  • Water-based
  • Two-part epoxy

The most common type of intumescent coatings used in the UK are water-based intumescent coatings. It is intended to centre our research investigations on a water-based intumescent coating available on the U.K. market. Water-based intumescent coatings are suitable for cellulosic type fires. They are the least expensive and produce less odour however they are less tolerant to humidity and low temperatures. Solvent-based coatings are used externally and internally and are tested against weather and temperature variations. Two-part epoxy coatings are normally used in harsher environments such as offshore or in the chemical industry (Bunchanan, 2001). 

Intumescent coatings can be applied by brush, roller or airless spray, on or off site, over the entire section, with a coating thickness  typically between 0.5mm and a few mm, but can be applied up to as much as 5mm (Bailey, 2009).