Paper by SWART TEUNS from ISCR 5th 1986 Aachen Germany
Since 1984 the county of ~oord-Brabant in the. ~etherlands is working out a programme ofconcrete cve r Lay i ng of old concrete pavements. These old pavements were mostly constructed in the 1960's. These roads, constructed on a sandbed,are unab Le to wi ths tand the increased weight and intens ity of modern goods traffic. Pumping effec ts occur at the joints. This results in differential settlement of the slabs and, at a later stage, structural feature. The first project is the concrete overlaying of the regional major road Eersel - Belgium ~rontier (S 17). It was the first project in Holland w1.th a concrete overlav on top of an old concre te pavement Land be~ides that, placed on a two-lane road with a slipform paver in one single operation. Totally the project has a length of about 12 km. For reasons of finance and organization the project is divided into 4 parts, starting in 1984 and finishing probably in 1987 Most of the crossings in the road have already been reconstructed. Each part of the project has its specific problems. For the first part it was dictated to place the overlay concrete over the full width of the two-lane road in a single operation, in order to minimize delay and inconvenience to road users. For the second part it was permitted to place the concrete in two operations, because of three crossings, which had to be reconstructed. The verge width and the possibility to handle the traffic had great influence on the way of placing the overlay. Much attention has been given to the place and the form of the joints including the dowels. In order to prevent reflection cracking, the concrete overlay has directly been placed on top of the old surface, without any intermediate layer. The overlay was 20 cm thick. The specifications contained requirements for a flat surface and for texture depth respectively for riding comfort and for road noise. The concrete quality was 45 ~/mm2 at a minimum after 28 days. In the part of the overlav of the year 1984, gravel was used as aggregates. it is an experiment to study the difference in breaking force with the part of the overlay of the year 1985 containinB broken stones as aeBregates. The contribution will deal for a big part with the execution of the concrete overlay. In the meantime a study is started to investigate if the delay for the road users can be shortened by using early strength concrete.