Fireproofing

Abstract: As evidenced by recent structural problems with fire-retardant-treated plywood, fire retardant chemicals and high temperature environments can degrade the strength properties of wood. We do not know to what extent fire retardant chemicals, thermal environment, and moisture content contribute to wood degradation. We suspect that the combination of acidic fire retardant chemicals and elevated temperatures increases the rate of acid hydrolysis in the wood, thereby causing a loss in strength. This paper presents a review of the pertinent literature on the factors influencing strength reduction in treated wood. These factors are the thermal degradation process of wood, the mechanism by which fire retardant chemicals alter wood degradation, the effect of acids on wood strength, the influence of temperature on strength, and the combined effect of fire retardant chemicals and temperature on strength. We also discuss possible long-term effects of in-service conditions on the strength of treated wood; the effects of treatment on the strength of weaker structural members and on species, size, and grade of lumber; and the application of the relationship between treatment and strength to plywood and lumber.

Abstract: Fire is a serious threat to people and the structures they build. There is a continuous development of newer methods and materials to prevent its effects on them. Nowadays, a lot of attention is being paid in the design of public and commercial buildings by incorporating fire safety. Passive fireproofing of high-rise structures has become very important due to the use of steel in load bearing mode and has attracted increased attention after the collapse of the WTC towers. Conventional passive fireproofing materials include concrete covering, gypsum board and cementitious coatings which have a poor aesthetic. Intumescent fire-resistive coatings are a newer type of passive fireproofing coatings usually applied as thin film and they swell many times their original thickness forming an insulating char which acts as a barrier between the fire and the structural steel. It prevents the temperatures of the steel members from reaching a critical value and helps in maintaining the integrity of the structure in fire event. They are the preferred choice for passive fire protection of load bearing steel frame structures of architects and designers as they offer aesthetic appearance, flexibility, speed of application, and ease of inspection and maintenance. The present review covers recent developments in the field of intumescent coatings with a major emphasis on organic intumescent coatings. The role of various ingredients, their interactions in intumescent coatings, effects of various pigments, binders and additives are discussed briefly.

Abstract: Fire retardant chemicals are designed to lower the temperature at which thermal degradation occurs. When these chemicals are used for roof sheathing, the combination of chemicals, elevated temperatures, and moisture can sometimes prematurely activate the fire retardant mechanism. The objectives of our study were to determine what kind of fire retardant chemicals are most susceptible to accelerating thermal degradation and at what temperature or temperatures this acceleration occurs. Small, clear Southern Pine specimens were treated with six different fire retardant chemicals and exposed to three environments for up to 160 days. The exposure conditions were (1) 80°F (27°C), 30 percent relative humidity, (2) 130°F (54°C), 73 percent relative humidity, and (3) 180°F (82°C), 50 percent relative humidity. Static bending tests were performed on the treated specimens and untreated controls to determine the effect of treatment and exposure on modulus of

Abstract: Intumescent compositions are described which when deposited on a substrate protect the substrate against heat and fire damage for an appreciable time, and these compositions are readily removed from the substrate by water washing or water scrubbing both before and after intumescing. Another advantage of these compositions is that they give off very little smoke when exposed to heat and fire. The most effective of these compositions comprise monoammonium phosphate and/or diammonium phosphate as a heat- and fireproofing agent, urea and/or cyanoguanidine (dicyandiamide) as a gas forming or gas generating agent to promote the intumescence, sucrose (sugar) together with the phosphate to promote initial intumescence at low temperature and titanium dioxide as a heat-reflecting agent. Certain possible alternatives to the compounds named above are also named.