Abstract:
In this investigation an attempt is made to study the
characteristics of bituminous macadam for road construction
in Bangladesh. This study includes the selection of a suitable
aggregate grading for bituminous macadam basecourse. Attempts
are made to study and compare the properties of brick-aggregate
bituminous macadam with those of natural aggregate bituminous
macadam.
Bituminous mixes using different types of aggregates
and in accordance with different gradings are studied. Effect
of types and amounts of filler on the behaviour of brick
aggregate bituminous mixes are investigated. Behaviour of
dense graded bituminous mixes with picked jhama brick aggregate
are investigated for different compactive energies. Study on
the effect of soaking period on the compressive strength
different mix types is also included.
Standard Marshall mix design procedure is followed in
the design and testing of these mixes. The testing includes
the determination of stability, flow, density, voids in the
mixes and the optimum asphalt content.
The study reveals that 'Picked Jhama' brick-aggregate
bituminous mixes are as good as crushed stone-aggregate mixes
for use in the basecourse of bituminous pavements, from the standpoint of stability, stiffness, deformation and voids
characteristics. However, the bitumen requirements for
one cubic metre of 'picked jhama' brick-aggregate bituminous
mixes is 66.14 kg more than those of crushed stoneaggregate
bituminous mixes. The investigation also indicates
the possibility of using non-plastic sand as a filler
material in the brick-sand bituminous mixes. It is also
found that soaking of bituminous macadam mixes for more
than 72 hours largely reduces the compressive strength.
Bituminous macadam base course mixes with picked jhama
brick aggregates give satisfactory results when they are
constructed using dense grading, good compaction, optimum
filler and subjected to lower soaking period.
