No abstract

facing the problem of VOCs pollution, VOCs concentrations in urban Tianjin have been measured to identify their possible sources. Using positive matrix factorization, seven VOC sources are identified in urban Tianjin according to the factor loadings of various VOCs, including: 1) motor vehicle exhaust; 2) gasoline evaporation; 3) internal engine combustion emission; 4) diesel emission; 5) solvent usage; 6) industrial emission; and 7) biogenic emission. The identified sources of VOCs are significantly related to vehicular activities, which specifically contribute 60% to VOCs loadings in urban Tianjin, respectively. Controlling vehicle emissions should be top priority for VOCs reduction in Tianjin.

In order to comprehensively evaluate the performance of dilution type cold patch asphalt mixture (CPAM), basic performances and deformation behaviors of dilution type CPAM under different stress modes were tested. The compaction performance and stability increasing property of CPAM were tested by rotation compaction test and Marshall stability test. The deformation behaviors of CPAM were tested by rolling test, small beam bending test and penetration shear test. Results show that when the using temperature is below 25°C, the compaction ability of CPAM is affected by temperature. The evaporation rate of organic solvents is slow, and affects the strength growing and rolling deformation behavior. It needs about 10d for the stability of CPAM rising to 3kN. The residue of organic solvents may lead the deformation of CPAM to constantly instability under rolling load. The stretching deformation and penetration shear deformation are affected by temperature. The low temperature and high temperature performance of CPAM is below standard requirements of hot asphalt mixture (HMA).