Politeknik Ungku Omar Civil Engineering Department Final Project Report Sesi Jun 2012 FPD windup (3)

1. CHAPTER 1
PRELIMINARY
1.0 INTRODUCTION
A flexible pavement structure typically consists of layers of different materials
that increase with strength as you move towards the surface (weakest layer on the
bottom , strongest layer at the surface). A flexible pavement relies on a layered
system to distribute traffic loads over the sub-grade. The load carrying capacity of a
flexible pavement is brought about by the load-distributing characteristics of each
layer in the layered system. The layers of a flexible pavement structure typically
consists of hot mix asphalt (HMA) at the surface, with the stabilized base, base
course gravel, and/or sub-base course gravel. Each of these layers contributes to

2. structural support and drainage. The surface course (typically an HMA layer ) is the
stiffest (as measured by resilient modulus) and contributes the most to pavement
strength .The underlying layers are less stiff but are still important to pavement
strength as well as drainage and frost protection . A typically structural design results
in a series of a layers that gradually decreases in material quality with depth.
Figure 1.1 : Basic Flexible Pavement Structure
The surface course is the layer in contract with the 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 , sub-base and sub-grades (NAPA , 2001) . This top structural
layer of material is sometimes subdivided into two layers (NAPA , 2001) :
i. Wearing Course . This is the layer in direct contact with the 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)

3. 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.
ii. Intermediate/ Binder Course. This layer provides the bulk of the HMA
structure. It’s chief purpose is to distribute load.
The base courses are usually constructed out of:
i. Aggregate. Base course are most typically constructed from durable
aggregates (see Figure 1.1) that will not be damaged by moisture or
frost action. Aggregates can be either stabilized or unstabilized.
ii. 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 subjected to
more lenient spec

4. Figure
1.2 : Limerock Base Course Undergoing Final Grading
The sub-base course is between the base course and the sub-grade. It
functions primarily as structural support but it can also:
i. Minimize the intrusion of fines from the sub-grade into the pavement
structure.
ii. Improve drainage.
iii. Minimize frost action damage
iv. Provide a working platform for construction.
The sub-base generally consists of lower quality materials than the
base course but better than sub-grade soils. A sub-base course is not
always needed or used. For example, a pavement constructed over a high
quality, stiff sub-grade may not need the additional features offered by a
sub-base 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 sub-base course can

5. offer. In this scenario the sub-base course may consist of high quality fill
use to replace poor quality sub-grade (over excavation).
The sub-grade is considered a part of embankment or natural soil and is
the layer which is 1 meter below the formation level (finished sub-grade surface).
It is a layer that provides a platform for materials above it to be constructed. Sub-
grade material that is considered suitable road construction.
Bitumen as binder material is widely used in flexible pavement
construction. Bitumen is a residual material which is produced by petroleum
distillation. Bitumen material has a useful characteristic as binder material. In
normal temperature bitumen has semi-solid characteristic and when increase the
temperature, bitumen will be soften and change to liquid. If the temperature
lower down to normal temperature, bitumen will be harden and back to original.
Penetration and flash testing are to be used for bituminous grading. Both of these
parameter is a measure of bitumen consistency at certain temperature. When the
bitumen to be used in the construction road pavement, bitumen must have the
appropriate grade, therefore its consistency will allow the paving work to be
carried out smoothly and produce the high quality pavement.
Certain test should be performed on each binder that will be used to
determine its properties. Tests are also conducted on the binder material to
predict the performance of a bituminous pavement that was constructed using
bitumen, Some test and analysis on bitumen are:

6. i. Penetration Test
ii. Softening Point Test
i. Penetration Test
This test is to determine the bitumen’s stiffness. In this
experiment, the standard depth of the needle into the bitumen can be
measured subject to certain conditions specified in the test. Normally the
temperature of the bitumen is 25 degree Celsius, the total load is attached
to the needle 100 grams and the time for needle penetrates into bitumen is
5 seconds.
For the type of soft bitumen, penetration depth is higher than the
type of hard bitumen. Therefore, the penetration test is very important
and it is widely used in classifying bitumen materials to certain grades.
Although the penetration test was defined as empirical testing, the test is
useful because it can be handled quickly and easily.
ii. Softening Point Test
This test is to determine the softening temperature for bituminous
material. When the temperature rises, solid bitumen will gradually and
imperceptibly change from brittle or exceedingly slow-flowing materials
to softer and less viscous liquid. Before bitumen mixed with aggregate to

7. be used as road pavement material, the condition of bitumen must be soft
so that it easily handled for paving works. The easiest way to soften the
bitumen is by heating. The softness of bitumen temperature level is when
it was tested under certain influence. The commonly performed test for
bitumen is ring and ball test. Known that hard grade of bitumen type has
a higher temperature level than the soft grade of bitumen.
Flexible Pavement Design’s Formula:
1) Vo= ADT x 0.5 x 365 x Pc / 100
2) Vc = Vo [ (1+r)x – 1 / r]
3) Vx = Vi ( 1+ r)x
4) ESA = Vc x e
5) C = I x R x T
6) C = 10 x c
7) n =
8) TA = a1D1 + a2D2 + a3D3
Where:
ADT = Average Daily Traffic
Pc = Percentage of commercial vehicles
Vc = Total number of commercial vehicles in one direction
Vo = Initial years commercial traffic

8. r = Rate of annual traffic growth
x = design period (year)
Vi = Initial daily traffic in one direction
I = Ideal hourly capacity
R = Roadway factor
T = Traffic reduction factor
1.1 STATEMENT OF PROBLEM
Through some reading and observation, we find out that too much
time is taken to determine the minimum thickness and the maximum
thickness of the flexible pavement, as it was done through manual
calculation. In addition, it is likely possible that calculation error creeps
in during the calculation process.
If there is any change in the design of flexible pavement,
all of the recalculation process should be done at an early stage so that the
thickness of flexible pavement and suitability of flexible pavement design
is identified early. The thinking of a layman using an automated simple
calculation procedure may significantly help out in this process.

9. 1.2 AIM OF THE PROJECT
This project is to produce a schematic layout of the calculation to
check the suitable measurement in flexible pavement design. The two
objectives are:
i. To prove that the calculation of Flexible Pavement Design can be
calculate by using Microsoft Excel (2007).
ii. To develop a software that allows students to compare the result
between two method (manually and computerization) as their
guidance in learning session.
1.3 THE IMPORTANCE OF THE PROJECT
The importances of the project are as follow:
1.3.1 Manual design may take longer time compared with
computerization design. Thus, at the end of the project, the
software (MS Excel) for flexible pavement design thickness is
developed that may minimize the time taken in design process.
1.3.2 Generally, the software (MS Excel) also avoid human error made
by the students during the calculation because it was developed
according to the standard method and all calculation is

10. computerized. Consequently, the result can be trusted and
unarguable.
1.4 THE SCOPE OF THE PROJECT
The scope for the study is focusing on the thickness design of
flexible pavement based on ATJ 1985 Manual. ATJ 1985 Manual is
suitable applies to the design of major road where the traffic is medium or
heavy. Apart from that, the computer software is verify with the manual
calculation to ensure the performance of computer software was
satisfactory without any error and provide an accurate result.
The project’s scope is getting a manual related to the usage of the
Flexible Pavement Design made out for a project, provide a programming
procedure with variable options for the flexible pavement design made
out for a project. Next, produce a program that meets the needs of the
user to compute the thickness and the suitability of the flexible pavement
being designed. In this project, no lab work and no site investigation shall
be conducted. Printing is to be minimized because going green towards
paperless. The project’s scope also includes semester 4, DKA 4C and
semester 5, DKA5A students in PUO as respondent.