Study On Odor Traceability And Odor Control Mechanism Of Crumb Rubber Modified Asphalt

Crumb rubber modified asphalt(CRMA)has been widely used in China and overseas,on account of its excellent performance and benefits by disposing of a large amount of waste tires.However,due to the odor emissions and poor workability of CRMA,its application is limited.Although desulfurized crumb can improve the workability and reduce emissions of CRMA,the odor issues of CRMA is still significant.In addition,there is a lack of evaluation parameters for the odor emissions and deodorant.Therefore,the present study aims at tracing the odor of CRMA.The attapulgite is selected as the deodorant of CRMA.The attapulgite’s odor purification mechanism and influence on performance of CRMA have been investigated.To clarify the composition of odor emissions of CRMA,the odor gas from the construction site of CRMA pavement was collected,and the gas chromatography-mass spectrometry(GC-MS)was been used to analyze the component of gas collection.GCMS headspace sampling method was used to conduct a semi quantitative analysis of the emissions of crumb rubber modified asphalt.Benzene emissions,alkanes,crumb rubber characteristic emissions,polycyclic aromatic hydrocarbons(PAHs)and other odor emissions were detected in the headspace test and on-site sampling test.Based on the results of filed gaseous sample and GC-MS analysis,combined with GC-MS internal standard method and indoor emission test,quantitative analysis was conducted on the odor emissions of 20% crumb rubber modified asphalt AR20,15%,20%,and 25% desulfurize rubber modified asphalt DAR15,DAR20,and DAR25.The GC-MS calibration curves have a high correlation coefficients and good quantitative analysis accuracy.In order to clarify the degree of odor emissions from various odorous substances,the triangle odor bag method was conducted to determine the odor threshold of each odorous substance.Based on the existing odor threshold database and the quantitative analysis results of odor emissions,the odor emission rate was established to trace the odor of CRMA.The results showed that xylene emissions and characteristic emissions of CRMA are the major source of the odor in CRMA.Based on the odor tracing results,attapulgite was used as deodorant to reduce the odor emissions of AR20 and DAR20.Odor evaluations were conducted on the odor emissions of two types of CRMA under 1%,3%,and 5%doedorant,respectively.The effect of attapulgite on odor purification was significant based on the observation that benzothiazole and xylene has been reduced substantially.Fourier transform infrared spectroscopy,BET analysis and thermogravimetric analysis(TGA)were used to investigate the targeted odor purification mechanism of attapulgite.Due to attapulgite’s special mesoporous distribution,attapulgite can adsorb the odor efficiently.The performance of CRMA containing different content of attapulgite was evaluated through temperature sweeping test,multiple stress creep recovery test(MSCR),surface energy test,Brookfield viscosity test,and differential scanning calorimetry(DSC)test.From a comprehensive perspective of odor reduction,performance,and economy,it is recommended that the optimal addition of the attapulgite is 5% and 1% for AR20 and DAR20 respectively.