Crack and seat has become an established technique for the cost-effective rehabilitation of flexible composite roads in the UK. However, as the treatment requires exposure of the underlying lean concrete base, it has, in the past, required the transportation and disposal of large amounts of asphalt planings and the placement of a new hot mix asphalt overlay.
Cemex UK Construction Services Limited (Cemex) were appointed as the main contractor for a major crack and seat maintenance scheme on the A46 trunk road in Warwickshire. In order to improve the sustainability of the maintenance treatment, Cemex sought to incorporate a layer of ViaFoam Cold Recycled Base Material (CRBM) in the new overlay. This material would be produced by Cemex in an ex situ process utilising the asphalt planings arising from the crack and seat phase of the scheme.
As this was believed to be the first time in the UK that a recycled material has been used over a crack and seat treated cement bound layer, verification was required that the proposed construction would satisfy the design requirements for both components.
This report contains details of the design approach used, observations during the construction of the scheme, presents the results of the in situ and laboratory testing and presents a discussion of potential future applicability of the combined treatment.
An estimation of the reduction in CO2 emissions owing to the use of the combination of crack and seat and ViaFoam in comparison to two conventional alternatives is also presented.

Want to know more about this project?