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.
The fact of a decreasing infiltration performance leads to accurate design, application and
maintenance proposals to achieve a long lasting infiltration performance on a high level for a
sustainable and environmental useful management of affordable drainage and sewer systems.