Aiming at the phenomenon of small size and concrete incompactness in the densely packed reinforcement in the web plate,the top plate and between the prestressed reinforcement,the concrete compactness coefficient is put forward based on the strength measurement principle using ultrasonic-rebound method.

Through formulae calculation,it is concluded that there are problems on values of vehicle density factor,as well as the problem on air pressure and air temperature modification for CO fresh air requirement.