The use of High Modulus Asphalt Concrete (HMAC) for base and subbase
has steadily increased for the last fifteen years. Several technologies
are suitable: selection of very hard bitumen, addition of asphaltite,
addition of polyolefins. Rich or lean mixes can be designed. Richer
mixes are easier to compact and less sensitive to water. The resistance
to rutting and the stiffness moduli are similar, irrespective
of the richness. The long term in-place behaviour can be rated
as satiafactory. A new type of HMAC has been designed to obtain
high fatigue resistance. It contains a high amount of binder,
which is a composite of very hard bitumen and polyolefin. The
first trial sections are being monitored. HMAC for binder and
wearing courses began to be used recently. They are designed to
reach not only high stiffness and excellent rutting resistance,
but also sufficient surface macrotexture. The observation of the
first sections laid shows no rutting under extremely heavy traffic
and an overall satisfactory performance to date.