As a ‘structural’ layer, CBGM offers benefits of improved whole life costing, with minimal repairs likely in comparison with an asphalt product. Depending on the design, CBGM performance can be equivalent to those of bitumen-bound materials. Research has shown that sub-bases could be laid up to 60% thinner than unbound granular sub-base, while producing an equivalent or better performance (TRL 248).
Using todays more versatile design approach, CBGM can be used as a sub-base replacement, providing the opportunity to reduce the thickness of the more expensive, overlying, pavement layers. In addition there is a reduction in excavation and muck shift works prior to construction. This has the added benefit of reducing contract duration which in itself is one of the largest potential cost savings.
Since CBGM can incorporate recycled or artificial materials, primary aggregate extraction can be minimised. The use a locally won aggregate when compared with the more stringent requirements of asphalt production may also prove beneficial in terms of cost, as well as CO2.