Paper by SMITS GEERLINGS from ISCR 11th 2010 Seville Spain
This paper reports about the results of test sections on a concrete cycle track, where natural aggregates were replaced by selected crushed concrete. The test sections were built in 2006 and monitored directly after the winter periods. In the three tested concrete mixes respectively 50% and 100% of the course aggregate was replaced and in one mix the total amount of course aggregate plus also the sand fraction was replaced by recycled concrete. All the mixes were placed by a slipformpaver. The first two mixes had a good workability for the slipformpaver. The last mix showed chewing-gum behaviour and could not be paved successfully and showed a bad surface that had to be repaired manually. The three test sections are observed for more than three years now and still show good performance also after two winters with lots of freeze thaw cycles. On basis of these results the road administration decided to standardise the use of recycling concrete on cycle tracks where 100% of the course aggregate is replaced by crushed concrete aggregate 4 / 32 mm. In the meanwhile more road administrations in The Netherlands decided to follow this example and a number of cycle tracks are paved in recycled concrete now. This paper reports about the backgrounds, the concrete mixes used, the specifications, the performance during paving and after construction and about the results of quality, evenness, frost-thaw resistance. Several projects with recycling concrete pavements will be shown.