NEW TECHNOLOGIES FOR CONCRETE PAVEMENT CONSTRUCTION

Abstract

New technologies for concrete pavement construction have been demonstrated on a 1750 m long access road to the freeway system in the Northern part of Jutland in Denmark during the autumn of 1995. The new technologies refer both to the cement treated granular base (ROADBASE) and to the concrete pavement itself. The latter being the result of a Brite-EuRam project "ECOPAVE". In the cement treated granular base 25 vol% of the materials are reused products which otherwise had to be landfilled. The reused products are old asphalt, low quality flyash and dust from cement kilns. Due to mechanical vibration a few days after paving, a system of microcracks have been established in the baselayer. For this reason no random cracking formed. The risk for reflective cracking in an overlaying asphalt- or concrete layer therefore is minimized. The concrete layer itself is constructed according to the ECOPAVE (ECOnomic PAVEment) principles. Active transverse cracks for every 1.5 m have been established within two days after paving, thus minimizing the crack widths and thereby eliminating the use of expensive dowels across the cracks. Due to the narrow crack width, load transfer is secured by interlocking between aggregates and rough crack surfaces. The 8.4 m wide, 120 mm thick, ROADBASE layer as well as the 8 m wide 200 mm thick ECOPAVE layer have been paved and totally compacted in full width only using an asphalt paver. The concrete was produced at a stationary concrete mixing plant. The mixing capacity equals a paving speed between 30 and 60 m/h. Even with a cement content as low as 260 kg/m3, and a content of microsilica of 20 kg/m3, the 28 days compressive cylinder strength is higher than 90 MPa. The concrete is freeze/thaw resistant, even in the presence of deicing chemicals though no air entrainment has been used.