The Analysis Of Temperature Variation And Temperature Field For Porous Cement Concrete Pavement

The porosity of porous concrete is usually between 15% to 25%, with permeability and permeable that Portland cement concrete does not have. Most of the current studies focus on the physical and mechanical properties, and to carry out the porous cement concrete pavement temperature change rule and the temperature field of study has strong theoretical significance and practical application value to have a thorough understanding of its using performance.In this paper, the study of porous cement concrete pavement temperature variation, heat transfer mechanism, regenerative capacity and temperature stress, provides the reference for porous cement concrete pavement structure design and application. In order to avoid the impact of the complex change of external environment on the temperature variation regularity of pavement structure, these research conduct a comparative trial of temperature changing law between portland and porous cement concrete pavement under the simulation condition of outdoor and indoor respectively. During the indoor experiment, a test device is designed which is used for test the heat release-absorption characteristics of pavement material, and study on the regularity of pavement structure in the windy and windless conditions. Finally,on a trial basis for common and porous cement pavement heat transfer mechanism, heat storage capacity and temperature stress of concrete are analyzed separately.The studies indicate that the temperature variation range of porous pavement is larger than Portland pavement, of whom both are far more larger than range of air temperature change. Rough surface of porous concrete with larger interconnected pores, and specific heat capacity is smaller, which are the main reasons that it heating up or cooling down rapidly than the common pavement. Under the condition of windless, above the middle of the plate,the distribution of temperature present non-linear more obviously, and the bottom half tends to be linear with the increase of depth. When there is no wind to cool the interior temperature during the test, temperature increases with increasing porosity, the reason is that the larger the porosity is, the more air the coarse aggregate contains, the more difficult for hot air to flow,and it will take the effect of heat resistance. When the wind speed reaches 4m/s, the temperature of the road surface decreases, and the porous specimen lead to greater coolingrate. The low thermal storage coefficient of porous cement concrete pavement is the mechanism of mitigating the local heat island effect of urban. In terms of temperature stress,the temperature stress of the specimen increases with the increase of the plate length. But when the plate length is certain, the internal temperature of the normal pavement warping stress is much greater than the porous pavement. Finally, combined the standard and the calculation results of the temperature stress, the suggestion that the horizontal joint spacing of porous pavement should be appropriately larger than the spacing of common pavement is suggested.