LONG-TERM IN-SITU INFILTRATION PERFORMANCE OF PERMEABLE CONCRETE BLOCK PAVEMENT

Abstract

SUMMARY Since it is a design criteria for road drainage and sewer systems, the infiltration performance of permeable concrete block pavement (CBP) is of important significance during the service life of a road construction. Due to the entrainment of mineral and organic fines into the pores of porous concrete blocks or into the aggregates used in joints or openings, the irreversible reduction of water permeability can be assumed. Research results show that the infiltration performance decreases in the order of the power to ten after a few years. These results are confirmed by in-situ field tests with a special infiltration-meter. This instrument measures the infiltration capacity in the laid condition with no disturbance and gives immediate results, taking into consideration local conditions such as age and traffic-load. The infiltration curves are shown as regression curves of the averaged infiltration values. These tests can be continuously repeated to observe the long-term performance. These tests show especially a significant relation between infiltration and age. The study states moreover that the long-term in-situ infiltration performance and its observed decrease depend from the grain size of the aggregates used for joint filling. It is furthermore partly induced by the ratio of openings of permeable pavements respectively the pore size of porous concrete blocks. The overall conclusion is that although permeable concrete block pavements cannot drain a traffic area entirely, they can still have a considerable impact on the run-off process of the entire catchment area. Due to the fact that part of the rainfall is retained, this part is not added to the run-off total and it can dampen the run-off peaks because of its delaying effect. In view of an overloaded sewer system this is of considerable ecological importance since the overload can be reduced by permeable concrete block pavements thus also avoiding discharge into the receiving water with the accompanying pollution. The respective relation between surface run-off and actual infiltration means for the hydraulic sizing of a drainage system that a more precise design method can be applied.