Title of Thesis
Impact of Superpave Mix Design Method on Rutting Behaviour of
Department Of Civil Engineering, Faculty Of
Civil & Environmental Engineering / University Of Engineering And
|Number of Pages|
|Keywords (Extracted from title, table of contents and
abstract of thesis)|
National, Progress, Superpave,
Rutting, Flexible, Hot, Mix, Asphalt, Pavement,
Behaviour, Methods, Design, Impact
communication is a key to national progress. Pakistan is located in
a region where South-Asia converges with Central Asia and the Middle
East. Blessed with extensive natural resources and rich agricultural
land, it improves its economy particularly by exporting valuable
items. In order to improve trade and economic activities and to
materialize regional linkages with China, Afghanistan, Iran, Russia
and other neighbouring Central Asian countries, the country is
gearing up towards a large infrastructure network. Roads constitute
a vital part of the infrastructure. In Pakistan most of the roads
are constructed using flexible pavement concept, due to their
comparatively low construction and maintenance cost.
Pakistan has national highways with a length over 9555 Kilometers
and motorways of 515 Kilometers.The drastic increase in traffic
volume during the last few decades has resulted in premature
pavement failures of almost the whole infrastructure of Pakistan.
Premature rutting of flexible pavements is one of the major pavement
distresses being faced by the country which is primarily due to
uncontrolled axle load and high ambient temperatures.Rutting in
asphaltic concrete depends on many factors, such as the composition
of asphalt mixes, grading and quality of aggregates, type of binder,
percentage of the bituminous binder, air void contents, degree of
compaction, environmental conditions, load repetition, the
substructure, and the bearing capacity of the subgrade.
The objective of this research work was to compare the Superpave,
Stone Mastic Asphalt (SMA) and Marshall methods of mix design of
asphaltic concrete and to propose rut resisting asphalt mix suitable
for local loading and environmental conditions. The mixes selected
for the study were dense graded in case of Superpave and Marshall
methods whereas gap graded for SMA.A comprehensive testing program
was conducted on the samples prepared in the laboratory at the
design asphalt contents and aggregate gradations.
Physical properties of aggregates and asphalt were determined in the
laboratory confirming to ASTM and AASHTO specifications. Mechanical
Properties of Marshall, Superpave and Stone Mastic Asphalt (SMA)
were evaluated by performing Indirect Tensile Modulus Test, Uniaxial
Loading Strain Test (Creep Test), Dynamic Modulus Test and Wheel
Tracking Test under prevailing load and environmental conditions of
Pakistan in order to compare the performance of mixes.
The study revealed that Superpave mixes performed better than
Marshall and SMA mixes in terms of low induced permanent strains,
high modulus of resilience, high dynamic modulus and better
resistance against wheel rutting during wheel tracking test.
technology can be adopted for the design of Hot Mix Asphalt (HMA)
pavements in the country due to its superiority over the
conventional mix design procedures. The guidelines for implementing
Superpave mix design procedure in Pakistan have been proposed.
In addition, a performance grading map has been proposed to be
implemented in Pakistan by dividing it into seven zones according to
the highest and lowest pavement temperatures.