Investigation on Smoke Suppression Mechanism of Hydrated Lime in Asphalt Combustion

Kai Zhu,Qi Zhou,Daquan Tang,Ke Wu,Yunhe Wang,Lingzhu Gu

doi:10.1155/2018/9585728

Abstract

In this study, cone calorimeter and thermogravimetric analyses were used to simulate the asphalt combustion process under the conditions of fire radiation and programmed temperature increase. The gaseous compositions and release rules were analyzed by infrared spectroscopy to investigate the influence of hydrated lime on the smoke suppression mechanism in the asphalt combustion process. The experimental results show that hydrated lime can promote the asphalt mastic surface to form a barrier layer during the combustion process. This barrier layer can reduce the burning intensity of asphalt. Although the compositions of gaseous products do not change much, the rates of CO production and smoke release are decreased. In addition, hydrated lime is alkaline and can thus neutralize acidic gases such as SO2 and reduce the toxicity of gaseous products. With the addition of 40 wt.% hydrated lime, the total smoke release and the CO release rate both decrease by more than 20% relative to the addition of the same amount of limestone fillers and decrease by more than 10% relative to the addition of the same amount of magnesium hydroxide flame retardant.

Highlights

Asphalt is a combustible mixture composed of hydrocarbons and relatively nonmetallic derivatives, which is wildly used in road pavement and waterproofing systems [1, 2]. e combustion of asphalt is typically accompanied with a quantity of toxic smoke [3, 4], seriously endangering any personnel within the affected areas
E process of material weight loss during a temperature rise was simulated by thermogravimetry. e smoke release situation during the heating process was analyzed by a Fourier-transform infrared spectrometer (Nexus670) and a thermogravimetric analyzer (TGA/SDTA851e)
10 mg of the sample was placed in an Al2O3 crucible, which was heated from 50°C to 850°C at a rate of 10°C min−1 and reacted at a constant temperature for 15 min. e gas-injected TG test system was composed of 21% oxygen and 79% nitrogen by volume

Summary

Introduction

Asphalt is a combustible mixture composed of hydrocarbons and relatively nonmetallic derivatives, which is wildly used in road pavement and waterproofing systems [1, 2]. e combustion of asphalt is typically accompanied with a quantity of toxic smoke [3, 4], seriously endangering any personnel within the affected areas. E combustion of asphalt is typically accompanied with a quantity of toxic smoke [3, 4], seriously endangering any personnel within the affected areas To solve this problem, applying flame retardant to asphalt has become a common way to reduce the hazards associated with pavement during tunnel fires [5,6,7,8,9,10,11,12]. Ese studies indicate that combustion test methods [4, 15], especially the fixed bed combustion test and cone calorimeter, can be used to simulate the actual burning environment with a high rate of temperature rise and strong radiation, but it is challenging to analyze the specific reaction process accurately. Is paper explores how hydrated lime influences the toxic smoke release during asphalt combustion by cone calorimeter analyses; it explains the mechanism of smoke suppression by hydrated lime via TGA-FTIR, providing a more complete understanding of the smoke suppression characteristics of hydrated lime

Experimental

Results and Discussion

Conclusions