Abstract:
In the current round of highway pavement betterment project in Indonesia, especially in West Jawa, Asphalt Treated
Base (ATB) with 55% of coarse aggregate is used as a regulating
course and is overlaid with a Hot Rolled Sheet mix containing 30%
of coarse aggregate. ATB, a gap graded mixture is very close in
composition to the BS 594-1985 specification for 50% coarse
aggregate and the HRS is very close to BS 594-1985 specification
for type F wearing course no. 9 (30/14). Information from the betterment projects indicates that the bitumen content of the HRS used is about 15% higher than that of the ATB mix. The purpose of the investigation described in this thesis was to compare these mixes on the basis of laboratory performance tests. Tests used were Marshall test, indirect tension test, wheel tracking test and skid resistance test. For the particular conditions under which this
investigation was carried out, it may be concluded that on the
basis of strength parameters the performance of ATB is comparable
with that of HRS. In terms of resistance to rutting at elevated
temperature (60 degree C), ATB has a clear superiority over HRS. ATB has an optimum binder content of 5.5% while that of HRS is 8.2%. The lower optimum binder content of the ATB combined with a high voids content (>8%) may present durability problems if this
material is used as a wearing course. Laboratory measurements of
skid resistance indicate equal performance in terms of BPN and
within the specified value for critical sites while the texture
depth of the ATB is approximately twice that of the HRS. Field mixes, as measured in the laboratory, is in excess of the maximum
value recommended for wearing course mixes in Indonesian
conditions. A study should be made of current methods of
aggregate production in order to establish if gradations obtained
comply with specification.
