21-11-2012, 06:31 PM
A CRITICAL REVIEW OF BITUMINOUS PAVING MIXES
USED IN INDIA
A Critical Review of Bituminous Paving Mixes Used in India.pdf (Size: 481.48 KB / Downloads: 215)
INTRODUCTION
The bituminous paving mixes as specified in MORTH
“Specifications for Road and Bridge Works”, Fourth
Revision, 200128 are commonly used in India. Some of
these mixes have evolved since 1960s, an era when the
present day hot mix asphalt plants were not common and
mixes were produced with small portable mixing plants
with limited aggregate heating, blending and mixing
capabilities. The proliferation of bituminous paving mixes
as specified in the MORTH publication basically manifest
the constraints of non-availability of modern hot-mix plant
besides likely cost reduction of lean bituminous mixes.
Today, the scenario has substantially changed. There is a
growing concern to construct long lasting pavements with
minimum maintenance. It is accordingly, felt that only those
specifications for bituminous mixes be allowed, which are
durable, irrespective of their location (NH or SH or Rural
Road) because durability and long term performance is
central to all of them.
Provide Surface Friction
Mixes like bituminous concrete, semi-bituminous
concrete, besides premix carpet, mix-seal surfacing is
commonly provided as per MORTH Specification as
wearing course. Some bituminous wearing course mixes
are designed to provide high surface friction especially
when the pavement is wet. Open-Graded Friction
Courses (OGFC) usually 20-25 mm thick (Figure 1b)
are designed as an open graded mix with interconnected
voids that provide drainage during heavy rainfall. OGFC
reportedly provides the following advantages12:
• Reduce splash and spray
• Reduce tyre-pavement noise14
• Enhance visibility of pavement markings, and
• Reduce night time surface glare in wet weather
PERPETUAL PAVEMENTS – AN EMERGING CONCEPT
The concept of Perpetual Pavement35 was first
launched by the Asphalt Pavement Alliance (APA) in a
joint promotional effort with Asphalt Institute, National
Asphalt Pavement Association, and the State Asphalt
Pavement Associations of USA in 2003-04. Fig. 3 depicts
the perpetual design concept.