Experimentally Determined Evaporation Rates in Pervious Concrete Systems

As the use of pervious concrete pavements increases, evaporation of storm water retained in the pervious concrete system becomes an important design parameter. This paper extends the knowledge of experimentally determined evaporation rates. The experimental setup consists of a column containing pervious concrete and coarse stone hanging in balance with a column of similar weight. The authors used a load cell to capture any changes in the weight between the two columns as the result of addition, drainage, and evaporation of water in the system. Results show the amount of water present in the system, cumulative evaporation, and evaporation rates calculated in terms of 24-h averages. The calculated evaporation rates start at a maximum of 0.02 mm/h and decrease with time, reaching a plateau towards the end of the experiment when the column is considered dry. In addition, the decreasing slope of evaporation rate curves with respect to the decrease in the amount of water present in the experimental column indicates that evaporation is a nonlinear function of the amount of water present in the system.