Transcript Construction Method for Road

Construction Method for
Road-Pavement
Introduction of Pavement
by : Ms Ikmalzatul
A. History
In its most general sense, a road is an open, generally
public way for the passage of vehicles, people, and
animals.
The earliest human road builders predate recorded
history by thousands of years. With the advent of
modern man, road building - the purposeful construction
of general public ways - became a common sign of an
advancing civilization.
Covering these roads with a hard smooth surface
(pavement) helped make them durable and able to
withstand traffic and the environment. Some of the
oldest paved roads still in existence were built by the
Roman Empire.
Roman Roads
By in large, Roman roads (see
Figure) were constructed during
the Republican times - the
oldest road, Via Appia, dates
back to 312 B.C.
the Roman road network
consisted of over 100,000 km
(62,000 miles) of roads.
The superior quality and
structure of its pavements have
allowed many Roman roads to
survive to this day.
The Rise of Bitumen
Tar Macadam Pavements
Road Mix Surfaces
Sheet Asphalt Pavements
Bitulithic Pavements
Others …
The Rise of Portland Cement
Concrete
The Original PCC Pavement
Portland cement concrete (PCC) was essentially invented in 1824. In 1889,
George W. Bartholomew proposed building the first PCC pavement in
Bellefontaine, Ohio. Bartholomew was convinced that his "artificial stone"
(the term "concrete" had not come into use yet) was a suitable substitute for
the brick and cobblestone of the day. In order to convince the city of
Bellefontaine to allow him to build his PCC pavement, Bartholomew agreed
to donate all the materials and post a $5,000 bond guaranteeing the
pavement's performance for five years. In 1891, the first truly rigid
pavement was mixed on site and placed in 5 ft. square forms.
Innovations in Performance
Innovations in Construction
Summary
Road and pavement building has often been used as a
benchmark of a civilizations advancement. The quality and
strength of many of the ancient roads has helped them survive to
this very day. The Via Appia in Rome is now over 2,300 years
old and is still used today. As the use of slave labor declined,
smaller more economical roads, such as Telford and Macadam
roads, began to arise. Around the beginning of the 19th century,
binding agents began to be used to assist aggregate cohesion
and improve the durability of roads. By the end beginning of the
20th century, the two principal pavement types, flexible and rigid,
had taken on many of their modern qualities and were being built
throughout in the world.
B. Pavement Overview
Pavement Purpose
Typically, pavements are built for three main purposes:
1. Load support. Pavement material is generally stiffer
than the material upon which it is placed, thus it assists
the in situ material in resisting loads without excessive
deformation or cracking.
2. Smoothness. Pavement material can be placed and
maintained much smoother than in situ material. This
helps improve ride comfort and reduce vehicle
operating costs.
3. Drainage. Pavement material and geometric design
can effect quick and efficient drainage thus eliminating
moisture problems such as mud and ponding (puddles).
Material Definitions
1. Hot mix asphalt (HMA). A combination of aggregate and
asphalt binder mixed together at elevated temperatures that
forms a hard, strong construction material when cooled to
ambient temperatures. HMA is known by many names
such as "asphalt concrete" (AC or ACP), "asphalt",
"blacktop" or "bitumin". HMA is distinguished by its design
and production methods and includes traditional densegraded mixes as well as stone matrix asphalt (SMA) and
various open-graded HMAs. Other types of bituminous
surfaces (such as slurry seals and bituminous surface
treatments) as well as various types of in-place HMA
recycling are separate from HMA.
2. Portland cement concrete (PCC). A combination of
aggregate, water and portland cement to form a hard,
strong construction material when set. PCC is known by
several names including "cement" and "concrete". PCC is
distinguished by its design and production methods.
Pavement Types
Much of this country relies on paved roads to move themselves
and their products rapidly and reliably throughout the
transportation system.
Pavements can be generally classified into two broad categories:
1. Flexible pavements These are asphalt pavements (sometimes
called bituminous pavements), which may or may not incorporate
underlying layers of stabilized or unstabilized granular materials
on a prepared subgrade. These types of pavements are called
"flexible" since the total pavement structure bends (or flexes) to
accommodate traffic loads.
2. Rigid pavements These are portland cement concrete (PCC)
pavements, which may or may not incorporate underlying layers
of stabilized or unstabilized granular materials. Since PCC has a
high modulus of elasticity, rigid pavements do not flex
appreciably to accommodate traffic loads.
Figures of Pavement
In United State of America
In Republic of Indonesia
Load Distribution on Pavement
Flexible pavements are those which are surfaced with
bituminous (or asphalt) materials. These can be either in the
form of pavement surface treatments (such as a bituminous
surface treatment (BST) generally found on lower volume
roads) or, HMA surface courses (generally used on higher
volume roads such as the Interstate highway network). These
types of pavements are called "flexible" since the total
pavement structure "bends" or "deflects" due to traffic
loads. A flexible pavement structure is generally composed of
several layers of materials which can accommodate this
"flexing". On the other hand, rigid pavements are composed
of a PCC surface course. Such pavements are substantially
"stiffer" than flexible pavements due to the high modulus of
elasticity of the PCC material. Further, these pavements can
have reinforcing steel, which is generally used to reduce or
eliminate joints.
Surface Course
The surface course is the layer in contact with
traffic loads and normally contains the highest
quality materials. It provides characteristics
such as friction, smoothness, noise control,
rut and shoving resistance and drainage. In
addition, it serves to prevent the entrance of
excessive quantities of surface water into the
underlying base, subbase and subgrade
(NAPA, 2001). This top structural layer of
material is sometimes subdivided into two
layers (NAPA, 2001):
1.Wearing Course. This is the layer in direct contact with traffic
loads. It is meant to take the brunt of traffic wear and can be
removed and replaced as it becomes worn. A properly designed
(and funded) preservation program should be able to identify
pavement surface distress while it is still confined to the wearing
course. This way, the wearing course can be rehabilitated before
distress propagates into the underlying intermediate/binder course.
2.Intermediate/Binder Course. This layer provides the bulk of the
HMA structure. It's chief purpose is to distribute load.
Base Course
The base course is immediately beneath the surface course. It
provides additional load distribution and contributes to drainage and
frost resistance. Base courses are usually constructed out of:
1. Aggregate. Base courses are most typically constructed from
durable aggregates (see Figure 2.5) that will not be damaged by
moisture or frost action. Aggregates can be either stabilized or
unstabilized.
2. HMA. In certain situations where high base stiffness is desired,
base courses can be constructed using a variety of HMA mixes. In
relation to surface course HMA mixes, base course mixes usually
contain larger maximum aggregate sizes, are more open graded
and are subject to more lenient specifications.
1.
2.
3.
4.
Subbase Course
The subbase course is between the base course and the
subgrade. It functions primarily as structural support but it can also:
Minimize the intrusion of fines from the subgrade into the pavement
structure.
Improve drainage.
Minimize frost action damage.
Provide a working platform for construction.
The subbase generally consists of lower quality materials than the
base course but better than the subgrade soils. A subbase course
is not always needed or used.
For example, a pavement constructed over a high quality, stiff
subgrade may not need the additional features offered by a subbase
course so it may be omitted from design. However, a pavement
constructed over a low quality soil such as a swelling clay may
require the additional load distribution characteristic that a subbase
course can offer. In this scenario the subbase course may consist
of high quality fill used to replace poor quality subgrade (over
excavation).
Flexible Pavement Types
There are many different types of flexible pavements. This section
covers three of the more common types of HMA mix types used.
This section provides a brief exposure to:
Dense-graded HMA. Flexible pavement information in this Guide is
generally concerned with dense-graded HMA. Dense-graded HMA
is a versatile, all-around mix making it the most common and wellunderstood mix type in the U.S.
Stone matrix asphalt (SMA). SMA, although relatively new in the
U.S., has been used in Europe as a surface course for years to
support heavy traffic loads and resist studded tire wear.
Open-graded HMA. This includes both open-graded friction course
(OGFC) and asphalt treated permeable materials (ATPM). Opengraded mixes are typically used as wearing courses (OGFC) or
underlying drainage layers (ATPM) because of the special
advantages offered by their porosity.
ROAD CONSTRUCTION
Aggregates
Asphalt/PCC
Laboratory Exp.
Design of Pavement Materials
Construction of Pavement Structures
Evaluation of Pavement Structures
Maintenance Programs
of Pavement Structures
THE END