Use of Porous Concrete Road Tiases in Belgium

Porous concrete is mainly used to prevent problems of water stagnation between a concrete pavement or a block paving surface and the base. In the new tender specifications SB 250 of the Flemish Region, requirements concerning porous concrete have been introduced, in particular • a percentage of voids of between 18 and 25 %, • an average compressive strength after 90 days ~! 15 MPa, • a minimum cement content of 200 kg/rn 3 . In the additional article n° 6 (lean porous concrete) of the G 155 standard schedule of specifications of the Namur Roads Department of the M.E.T., a porosity of 10 to 15 % and a mean compressive strength on 20x20 cubes of minimum 11 MPa after 28 days are required. Despite the good results achieved both abroad and in our own country (for example, in the subbase of emergency hard shoulders on the N4 in Assesse), the use of porous concrete still remains too limited.