Thermal Gradients in Concrete Pavements in Tropical Environment: Experimental Appraisal

Abstract

Fifteen concrete slabs were instrumented with thermal resistors, allowing the monitoring of temperatures in concrete pavements slabs in São Paulo, Brazil, where a typical tropical hot and wet environment prevails. Over the course of 1 year, this research sought the influence of climatic conditions such as temperature and moisture on the daily and seasonal variations of temperature differentials through the slab depths. Daytime temperature differentials of more than 15°C were observed during typical summer days (e.g., high air temperature of 32°C and 7.6 h of solar radiation) and of about 10°C during typical winter days (e.g., low air temperature of 11°C and 3 h of solar radiation). The absolute values of nighttime temperature differentials are not as extreme as the daytime differentials and are significant mostly during spring and summer (from September to March). Nonlinear quadratic temperature distributions through the slab thickness were evident in most cases; nevertheless, distributions that are almost linear may be present at some times during the day and even at night. Positive temperature differentials were recorded even at night, and discussions of those particularities are addressed. The effects of tropical rains on temperature differentials are presented, and empirical models for the prediction of temperature differentials in slabs are suggested.