The Chilled-mirror Dew-point Detection System For Greenhouse Gases Of Pavement

As an important indicator of pavement quality assessment, water content should be strictly controlled. The change of pavement humidity directly affects its strength and stiffness. Detection of pavement humidity has important significance for the development of highway construction during construction and maintenance period. In this paper, a chilled-mirror dew-point detection system was developed which use for greenhouse gases of pavement in order to overcome the defects of traditional methods which were complex operations, longer test cycle and couldn’t correct the problem in the construction process in time.Through investigation and research about the advantages and disadvantages of domestic and foreign chilled-mirror dew-point instruments, combined measurement technology of pavement humidity, this article designed a chilled-mirror dew-point detection system for greenhouse gases of pavement.In this paper, the fundamental of hilled-mirror dew-point detection and the possible problems were first analyzed in the measurement process, determined the gas’ s dew-point detection method in a complex pavement environment. The general design and encapsulation of chilled-mirror dew-point detection system was proposed. Secondly, the dew-point detection system hardware design has been completed, which include core controller module mainly contains the peripheral circuit of microcontroller and analog to digital conversion circuit design. Photoelectric detection module was consist of illuminant, chilled-mirror and photoelectric sensor. Semiconductor refrigeration module mainly designed the three-stage refrigerator, power control circuit and cooling system. The dew-point detection system software design was accomplished, including control and data collection of microcontroller, such as subroutine of A/D sampling, subroutine of serial communication, subroutine of LCD driver and subroutine of PWM output. The detecting software which meets the needs of dew-point measurement was developed in Lab VIEW environment. The detecting software consists of serial port communication module, dynamic display module, data processing module and database management module.