Paper by SOMMER from ISCR 8th 1998 Lisbon Portugal
A recycling concept has been used since 1991 for reconstructing 120 km of carriageway on the concrete motorway Salzburg - Vienna: The old concrete is crushed and the coarse material used as the aggregate for the new concrete pavement. The fine fraction is added to the old granular subbase thus ensuring enough sand for the subsequent stabilization with cement. On recent reconstruction projects, because of the increase of traffic, the new pavement had to be built with 3 travelling lanes (instead of 2), for which the old pavement did not provide all the aggregate. The use of the old asphalt shoulder is heing considered as an additional source of aggregate: a small section was paved in 1997 with 35 % of the coarse aggregate replaced by reclaimed asphalt. In some parts there is a tar-bound subbase below the old concrete pavement. Stabilization with cement prevents leaching of phenols and PAH into the groundwater. In case of a naphtalene a special cement with adsorbing constituents was shown to be more effective than Portland cement and in 1997 was used succesfully on a motorway site to bind this contaminant.