Laying Asphalt at Low Temperatures : a pilot project in the Netherlands

When a severe winter causes substantial road surface frost damage such as excessive ravelling of porous asphalt pavement, conventional maintenance methods have little to offer when it comes to effecting repairs. It is well known that laying asphalt by conventional methods at temperatures below 5ºC can lead to an asphalt layer of less than the customary quality. To find out whether paving is possible in winter conditions without prejudicing quality, Rijkswaterstaat first carried out a preliminary investigation or ‘Quick Scan’. The Quick Scan provided sufficient evidence to justify a trial under operating conditions. In February 2010 Rijkswaterstaat commissioned a trial on the A58 motorway, where in sub-zero temperatures two contractors each laid a PA+ (improved PA) test section 300 meters in length. During construction extensive measurements were taken. Core samples were also taken for testing in the laboratory and visual inspections were carried out. On the basis of the measurements it may be concluded that the special measures taken contributed to achieving a PA+ layer of good quality. Laying asphalt at low temperatures has always been attended by the risk of poor quality. In view of this and the cost of the extra measures needed, paving in cold winter weather is recommended only in situations in which major road surface repairs are urgently needed in order, for example, to keep traffic moving and/or maintain road safety.