Rehabilitation of the Antwerp Ring Road
The R1 is a 14-km ring road which surrounds the city of Antwerp and was opened to traffic in 1969. The road was first rehabilitated between 1976 and 1977, with some sections of the road being widened to up to 7 traffic lanes. However, an increase in traffic intensity to nearly 200 000 vehicles per day led to the need for a complete structural rehabilitation of this motorway.
After a thorough comparative study of the different alternatives, the main part of the existing pavement was replaced with a new pavement structure consisting of 23 cm of continuously reinforced concrete supported by a 5 cm thick bituminous asphalt inter-layer, 25 cm of cement-stabilised asphalt rubble and 15 cm of recycled crushed lean concrete. A fine-textured exposed aggregate concrete surface (0/20 - nominal aggregate size is 20 mm - concrete with cement content of 400 kg/m³) was applied in order to obtain an excellent skid resistance combined with a reduction of the rolling noise. Since the mid-nineties, the standard construction method for concrete roads in Belgium has been paving in continuously reinforced concrete with a thickness of 23 cm and a chemically exposed aggregate surface finish. The concrete road surface is laid in a single run of a slipform paver. This method is simple and reliable. A suitable macrostructure is required to obtain a low-noise road surface, i.e. the uniform distribution of fine stones – up to approx. 10 mm in grain size – on the concrete surface. This is taken into account, in the concrete composition, by imposing a maximum aggregate grain size of 20 mm and by keeping the content of fine stones (fraction 4/6.3) high, i.e. 20% to 25% of the sand/stone mixture.