To evaluate the potential of wire-fibre-reinforced concrete for thin overlays on heavily trafficked concrete roads in great britain, a full-scale experiment was carried out on a length of reinforced concrete carriageway on the m10 motorway, which had been in service for 15 years and had suffered some cracking. The overlay was constructed in two thicknesses, 60 mm and 80 mm, and three fibre contents were used, 2.7, 2.2 and 1.3 per cent by weight of 0.5 mm x 38 mm duoform wires. 16 test sections were laid, some of which were bonded to the original pavement slab and some only partially bonded. The total length was 200 metres. Mixing was performed at a nearby readymix concrete plant and a slip-form paver was used for laying. Expansion joints were formed in the wet concrete over the expansion joints in the original pavement; additional contraction joints were also formed in the overlay. After a year of heavy traffic examination of cores showed that the bonding technique was satisfactory, the partially bonded sections had no effective bond and that wire bond across cracks was effective. The best performance, in terms of surface cracking, after 2 years of traffic, appears to be given by the thicker partially bonded sections; damage is at present mainly limited to hair cracking. No final conclusions can yet be reached on performance since the road has not been subjected to any very cold weather. It remains to be seen whether the combined effects of heavy salt application and increased carbonation of the concrete in severe winters will permit sufficient corrosion of the fibres at cracks that they are no longer effective. (Author/publisher)
Abstract