Effect of Temperature Difference on the Thickness Design of Pervious Concrete Pavements

Abstract

Pervious concrete pavement (PCP) is a porous paving material that facilitates the rapid infiltration of runoff. The significance of temperature difference (ΔT) between the top and bottom of traditional concrete pavements for stresses and structural design is well known. However, with their low thermal conductivity, the question exists whether PCPs develop large ΔTs that vary during the day and between seasons. If so, the extent of the effect of such ΔTs on stresses in the slab and the thickness design of PCP needs to be investigated. In this study, temperature data collected from three PCP sections (in two different climate regions) instrumented with thermocouples were used to analyze ΔT for multi-year periods. Frequency distribution of ΔTs showed bimodal trends with peaks ranging between –6°C and 17°C occurring during the day and night of spring and summer seasons. In winter, ΔT distribution was unimodal, with peaks ranging from 0°C to 3°C. Finite element analysis was conducted to quantify the stresses in PCP sections with different flexural strength ( MR) and modulus of subgrade reaction under combinations of critical ΔTs and axle loading. The resulted stresses were used in a PCP fatigue model to estimate fatigue life and slab thickness for PCPs. Based on the expected load repetitions in a 20-year design life, a database of recommended thicknesses for PCPs with various material properties and under four traffic categories was developed. Increasing MR from 2.4 to 3.1 MPa resulted in reducing PCP design thicknesses by 20–55 mm under the same loads. Moreover, incorporating ΔT in the thickness design of PCP resulted in a higher minimum required thicknesses by up to 100 mm compared with PCP with no ΔT under the same traffic loads.