BS EN 12697-40-2020 Bituminous mixtures – Test methods – Part 40: In situ drainability.
6.3 Measurement at each location
6.3.1 Place the permeameter over the surfacing at the point where the relative hydraulic conductivity is to be measured. Apply a vertical load uniformly on the base such that all four of the rubber feet on the standing board are in contact with the surface to be measured.
A load of between 1 kN and 2 kN should achieve this contact.
The load can he applied either mechanically or by two operatives of approximately the same mass standing on opposite sides of the standing board. II two operatives are used, the heavier operative should not weigh more than 50 % more than the lighter operative.
6.3.2 Fill the standpipe completely with clean water.
6.3.3 Remove the plunger and hang it by its rest on the top of the standpipe. Allow air bubbles to rise up through the water in the standpipe until they no longer rise through the water, which is dissipating into the road surface.
6.3.4 If air bubbles are still rising through the water in the standpipe when the meniscus nears the 5 I mark, replace the plunger and refill the standpipe to at least 50 mm above the 5 I mark. Without delay, remove the plunger and hang by its rest on the top of the standpipe.
6.3.5 Repeat 6.3.4 until no bubbles are rising through the water in the standpipe when the meniscus nears the 5 1 mark
The pores of the surface should be saturated by water for the test to give the required result, which can
be achieved by emptying the permeameter of water before refilling and starting the actual test
However, this procedure should not normally be needed if the permeameter is filled to well above the
5 I mark.
6.3.6 Start the stopwatch when the meniscus falls to the 5 I mark Stop the stopwatch when the water level falls to the 1 I mark Record the outflow time, t1,, to the nearest 0,1 s.
6.3.7 Repeat 6.3.2 to 6.3.6 in order to obtain ti.2.
6.3.8 Calculate the average outflow time as (t1,1+ t12)/2 and the range as tLl — ti2I for the location, both to the nearest 0,1 s. If the range exceeds 5% of the average outflow time, repeat 6.3.2 to 6.3.6 until the range criterion is met by two successive outflow times and discard outliers. Record the average outflow time for location i, t1, to the nearest 0,1 s.
NOTE Locations where there is a transition gradient might produce results that are inferior to results obtained from the material under other circumstances.
7 Calculation
7.1 Calculate the average outflow time for the test, t, as the mean of the 10 values of t1 for locations 1=1 to 10.BS EN 12697-40 pdf download.