Preparation And Characterization Of Fireproof Coating For Tunnels

Tunnel construction has been throughout the world and the benefits offered by passive fire protective coatings have being increasingly acknowledged. Various tunnel fires might be small with the ignition of a small vehicle carrying a low fire load, or be large and intense with the ignition of a fuel tanker. With the general increase in traffic volume and the transport of hazardous goods, the risk of an incident involving fire might be increasing continuously.Recent fires in many tunnels have shown that the intensity of real tunnel fires can be far greater than expected and the damage to structure. Long closure periods and loss of revenues can have catastrophic consequences to both the tunnel itself as well as the surrounding environment. In an immersed tube tunnel, loss of the joint seals in a fire would destroy the tunnel.Silicate fireproof coatings for tunnels (FCT) possessed many eminent properties, but its applications could be limited due to the low adhesion strength and poor water/fire-resistance. In this study, a new kind of FCT has been developed with Portland cement as principal adhesive, redispersible latex powder as assisting adhesive, ammonium polyphosphate as fire-retardant material, vermiculite as adiabatic padding, and magnesium hydroxide as assisting reagents. The influence of various experimental conditions on fire resistance, adhesion strength and water resistance had been studied in detail.1. The optimized formulation of fireproof coating for runnels has been determined. Compared with commercially available ones, this proposed FCT possessed excellent physical-chemical properties, such as high bond strength, good crack-resisting and weather-resisting property.2. The binding admixture consisted of high alumina cement, Portland cement and redispersible latex powders was used in the fireproof coating for the first time, and the redispersible latex powder played a key role on the adhesion strength and the water-resistance of FCT. When adding 6wt% redispersible latex powders to FTC, the adhesion strength could be greater than 0.9 MPa.3. Cement admixture (high alumina cement and Portland cement) and inflatable flame retardants such as APP, PE and MEL significantly influenced the fire resistance of the FCT. When the thickness of the dry film was 10mm, the fire-resistant time of FCT added 6 wt% of flame retardants could last over 180min.4. The water-resistance of this FCT (360 hours, exceeding the criterion claim 24 hours far away) could absolutely meet the need of inclement environment in the tunnels.5. This new kind of mono-integradient FTC could be easily applicated, and the costs for transportation, storage and package might be greatly reduceed.