A Research Proposal on Asphalt Pavement Quality Control in Kuwait

This research proposal focuses on asphalt pavement quality control, addressing issues related to Hot Mix Asphalt (HMA) mixes and pavement distresses. The proposal emphasizes the importance of quality control throughout the pavement's lifecycle, from design to post-construction. It highlights the objectives to provide a clear guideline for improving pavement quality in Kuwait, preventing problems like ravelling and addressing poor asphalt quality, which is a widespread concern. The methodology includes understanding quality control procedures, research questions, and evaluating methods like visual analyses, lab testing (Marshall Stability, Immersion Compression, DSR, BBR, PAV), and sample testing. The proposal covers asphalt pavement composition, including aggregates, liquid asphalt (bitumen), and additives, and discusses testing equipment like the Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), and Pressure Aging Vessel (PAV). It also addresses the main causes of pavement distresses such as heavy traffic, climatic changes, poor mix design, and aggregate segregation. The research aims to classify pavement distresses as either structurally or functionally related, including fatigue cracking, rutting, ravelling, and bleeding. The proposal emphasizes the significance of quality control during design, before, during, and after pavement placement to ensure durability and performance.

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RESEARCH PROPOSAL ON ASPHALT PAVEMENT QUALITY CONTROL
A Research Paper on Asphalt Pavement By
Student’s Name
Name of the Professor
Institutional Affiliation
City/State
Year/Month/Day

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Table of Contents
1.0 INTRODUCTION.....................................................................................................................................2
2.0 OBJECTIVES............................................................................................................................................3
3.0 BACKGROUND.......................................................................................................................................3
4.0 METHODOLOGY.....................................................................................................................................3
5.0 ASPHALT PAVEMENT.............................................................................................................................4
6.0 ASPHALT MIXTURE................................................................................................................................7
7.0 MAIN CAUSES OF DISTRESSES...............................................................................................................8
Heavy Traffic............................................................................................................................................8
Climatic Changes.....................................................................................................................................8
Poor Mix Design.......................................................................................................................................9
Segregation of Aggregates.......................................................................................................................9
Types of Pavement Distresses.................................................................................................................9
Structural Related Distresses.............................................................................................................10
Functional Related Distresses............................................................................................................10
8.0 QUALITY CONTROL..............................................................................................................................11
During Design........................................................................................................................................11
Quality Control before Placing...............................................................................................................12
Quality Control during Placing...............................................................................................................12
Quality Control after Placing..................................................................................................................13
9.0 CONCLUSION.......................................................................................................................................13
10. BIBLIOGRAPHY.....................................................................................................................................14

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1.0 INTRODUCTION
This project proposal is about the asphalt pavement as well as the issues related to the asphalt
pavement and how quality control can help in decreasing these effects by performing lab tests on
cores extracted from the site, checking compaction, checking the raw materials of the mixture,
and checking the temperature of the mixture. Quality control is a significant aspect of pavement
placement and construction globally. Quality control provides a guideline in which an engineer
or a contractor can follow to make sure that the pavement was correctly placed, correctly
transported, and also correctly mixed. The aspect of quality control extends during the entire
duration of the pavement, even after the construction of the pavement, and is in service since
routine and regular checks are significant to make sure that pavement quality still complies with
the standards.
2.0 OBJECTIVES
The major objective of this project proposal is to provide a clear guideline to quality control
which can be applied to improve the pavement quality in Kuwait and help in preventing
problems related to HMA mixes and ravelling.
3.0 BACKGROUND
One of the widely spread problems in Kuwait is the poor asphalt quality. The asphalt pavement
quality is a very significant feature when determining the performance of the pavement. Poor
measures of quality control may result in numerous issues of safety and need frequent road
maintenance. Lack of proper quality control may result in poor pavement quality which when
used may increase the number of particle aggregates to dislodge and hit the moving vehicles on
the road hence resulting into damages to the body and windshield of the vehicle. Measures of
quality control can be implemented to ensure that the designs of the mix are subjected to the

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control measures necessary which will prevent poor HMA quality of going into service. This will
result in reduced damages caused by the degradation of roads and maintenance cost (Feipeng &
Serji, 2009).
4.0 METHODOLOGY
Comprehend the various aspects for quality control procedures and measurements for HMA
mixes and their impacts on the asphalt pavement. The research questions include; Why is quality
control significant? Which areas should quality control be performed? What is the procedure of
performing quality control? When should quality control be performed? What are the procedures
of performing quality control for HMA mixes? What are the effects of quality control measures
on HMA performance? (Grédiac & Toussaint, 2013)
Using the procedures of quality control during the entire process. The procedures involved
during the quality control include Quality control at design- Laboratory, Quality control at the
construction site- Before placing, Quality controls at the construction site- During placing, and
Quality at construction site-After placing.
Evaluating the methods of quality control using methods that have been proven.
1. Visual analyses
2. Lab testing: Marshall Stability test, Immersion compression test, DSR, BBR, and PAV.
3. Sample testing: (Sample extraction from aged HMA mixes and recently placed HMA
mixes)
4. HMA distresses (Types of loadings subjected to HMA)
5. Performance testing (testing during service of the pavements) (Guo, 2013)
5.0 ASPHALT PAVEMENT
Asphalt pavement is made up of aggregate (stone), liquid (petroleum) asphalt, additives, and
sand. Liquid asphalt which is also referred to as bitumen is a sticky substance and is used in
binding materials in the asphalt pavement. After being mixed, the pavement is composed of 5 to
10% bitumen or asphalt and 90 to 95% sand and aggregate. Mineral aggregates entail fine and

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coarse aggregates. Fine aggregates are normally crushed stone or sand which are less than
9.55mm in diameter, while coarse aggregates are particles which are greater than 4.75mm
(Chiara, et al., 2015).
Figure 1: Particle size distribution for aggregates (Juan & Yu, 2016)
The high viscosity of asphalt binds the materials which make up asphalt pavement while
permitting it to retain its flexibility simultaneously. The first step of producing asphalt pavement
is known as predose and during this process, the components of the aggregates are weighed by
the use of belt weigher. The second step is drying of the aggregate components which are done
by the use of a rotary drying drum where the components are dried up to 300oC (Kun &
Balasingam, 2018).
The aggregates are then transferred to the mixer where the liquid asphalt is stored in a different
heated tank to retain its liquidity. The asphalt is then added to the aggregate depending on the
rate of flow determined. Both the binder and the aggregates are thoroughly mixed to form the
paving materials.
Dynamic Shear Rheometer (DSR) is used in characterizing the elastic and viscous behaviour of
asphalt binders at high to medium temperatures. The characterization attained is used in the
specifications of the Superpave PG binder. The DSR determines the phase angle and complex

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shear modulus of the specimen. The larger the phase angle, the more viscous is the material
(Mohamed & Maciej, 2014).
Figure 2: Dynamic Shear Rheometer (Niklas & Terhi, 2016)
Bending Beam Rheometer (BBR) is a test performed to provide a measure of relaxation
properties and low-temperature stiffness of asphalt binders. These parameters provide an
indication of the ability of asphalt binder to resist low temperature cracking. The BBR is used
together with the DTT to evaluate low-temperature PG of an asphalt binder. The basic test of
BBR uses a small asphalt beam that is supported simply and immersed in a bath of cold liquid. A
load is then applied to the central position of the beam and its deflection determined against time
(Nouffou & Cédric, 2014).

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Figure 3: Bending Beam Rheometer (BBR) (Rodrigo & Hussain, 2010)
The Pressure Aging Vessel (PAV) provides a long-term simulated age asphalt binder for
physical property testing. Asphalt binder is exposed to pressure and heat to simulate in-service
over a period of 10 to 7 years. The basic procedure of PAV takes samples of RTFO aged asphalt,
positions them in stainless steel pans and then ages them for 20hrs in a pressurized heated vessel
to 20.7 atmospheres.
Figure 4: Pressure Aging Vessel (Tan, et al., 2014)
6.0 ASPHALT MIXTURE
The most common types of asphalt pavement surfacing are the hot mix asphalt (HMA) which is
known by numerous names such as bitumen, blacktop, asphalt concrete (AC) or hot mix. HMA

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is distinguished by its method of production and design and involves stone matrix asphalt as well
as traditional dense-graded mixes. HMA pavements are categorized majorly as open-graded hot
mix asphalt, stone matrix mixes, and dense-graded mixes (Tao & Feng, 2011).
Marshal Stability Test
The specification of the mix properties so that it will have enough stability to resist displacement
under traffic is a continuous problem in the design of the asphalt mix. The Marshal Stability test
shows that the capacity of a bearing of a paving mix can be related to flow and marshal stability
by the equation:
Bearing capacity =
1
5 Stability
Flow X ( Z+ K ) F
; Where K = 1+Sin PHI - SIN SPHI
The curve of the design representing the equation above shows that the load-bearing ability of an
asphalt mix is a function of the value of flow and also a maximum flow value and minimum
stability (Tong & Yuan, 2014).
Immersion Compression Test
In this test, two samples of asphalt pavements are prepared using gyratory compactor. The
expected air void content is 6% and a compression strength of 25.0oC without conditioning. The
other sample conditioned by immersing in water for 24 hours is expected to be 60.0oC.
7.0 MAIN CAUSES OF DISTRESSES
There are numerous factors which contribute to the distresses in the asphalt pavement, some of
these factors result in failure of the highway such as poor workmanship, use of low-quality
material for construction, poor maintenance and construction, aggregate segregation, poor mix

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design, installation during wet weather, dust coating, dislodging from heavy traffic, and also
poor design (Wu, 2017). These factors have been discussed below:
Heavy Traffic
Distresses of the asphalt pavement is one of the defects caused by heavy traffic on the road as a
result of overloading that is more compared to the design load. Distresses of the pavements arises
from the deformation associated generally with cracking under heavy vehicles. The increased
loading caused by the traffic will then result in failures such as depression and cracks. The
surfaces of the pavements normally wear under the effects of the traffic, specifically during the
early stage of the pavement. However, the action of the traffic continues to wear the texture of
the surface and hence gradually minimizes the resistance of high speed skidding (Xiao, 2009).
Climatic Changes
Some of the climatic factors which may result in distresses of the asphalt pavement include
annual variations in temperature and rainfall. Rainfall has a significant impact on the strength
and stability of the layers of pavement since it affects the content of moisture of subgrade soil.
Rainfall is also known as a factor which affects the infiltration of water, pumping, the intensity
of erosion, and the elevation of the water table. After the water has entered in the road pavement,
the initial damage is caused by hydraulic pressure and any vehicle passing on top of these
pavements impact sudden pressure on the water and this pressure forces the water further into the
fabric of the pavements and breaks it up (Xiao, et al., 2017).
Poor Mix Design
The use of poor mix design during the construction of the asphalt pavements affects the
performance of these pavements adversely. This normally occurs when there is improper grading
of aggregates for the sub-base or base and poor subgrade of low bearing strength. The use of
substandard or marginal base materials for the construction of the pavement will influence the

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performance of the pavement. These poor mix designs may accelerate deterioration of the
pavement and normally result in shortened service life, low strength, low skid resistance,
aggregate abrasion, ravelling, shoving, cracking, and rutting (Yong, 2010).
Segregation of Aggregates
Segregation of the aggregates is considered one of the most common causes of distresses in
asphalt pavements. One of the most common distresses form in low volume pavement is the
longitudinal cracking results from the changes in the volume of the expansive aggregates such as
subgrade. This type of cracking is commenced from drying highly plastic subgrade through the
structure of the pavement during the summer. The problem of segregation of aggregates is as a
result of wide range of factors like compression of the soil strata, poor surface drainage, the rise
of groundwater, or the type of clay minerals (Yuhong & Dan, 2017).
Types of Pavement Distresses
The various types of pavement distress can be classified as either functionally related distress or
structural related distresses. The structural related distresses include potholes, fatigue cracking,
rutting, and shoving. The functional related distresses include ravelling, bleeding and flushing,
and also roughness.
Structural Related Distresses
Fatigue cracking: Cracks in the layers of asphalt pavements are generally caused by continuous
traffic loading. The cracks indicate the failure of fatigue of the asphalt pavements. When
cracking is characterized by cracks that are interconnected, the pattern formed by cracking
resembles that of a chicken wire of the skin of an alligator (Zhang, 2018).
Rutting and Shoving: Rutting is a longitudinal depression of the surface which develops in the
paths of the wheels of flexible asphalt pavements under traffic. It is another form of transverse
displacement. Very server rutting will hold water in the rut hence causing a failure in a single or

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many pavement layers. Minor surface rutting can be filled with paver-placed surface treatment or
microwaving.
Shoving is a longitudinal displacement of a localized section of the asphalt pavement surface.
Shoving is normally caused as a result of sudden acceleration or braking of the vehicles and is
normally positioned on curves or hills.
Potholes: Potholes of holes with a shape of the bowl of numerous sizes on the surface of the
asphalt pavement. These potholes have a minimum dimension of 150mm. They are a progressive
failure. Potholes are normally situated in regions if poor drainage and are formed through the
disintegration of the pavement under traffic loading (Zhijiang, 2017).
Functional Related Distresses
Ravelling: Ravelling is the wearing out of the surface of the pavement in the high-quality hot
mix asphalt concrete which may be as a result of the loss of asphalt binder and dislodging of
aggregate particles.
Roughness: This is where the surface of the pavement becomes distorted an is caused by the
instability the asphalt surface having too much smooth textured coarse aggregate, too much fine
aggregate, or too much asphalt cement (Xiao, 2009).
Skid resistance: Skid resistance is caused by the excess asphalt on the surface of the pavement,
lack of enough water on the surface, and also polished aggregates. The major consideration that
should be taken to ensure that the skid resistance is at an acceptable level is to allow water to
flow off the pavement.
Bleeding/ Flushing: Bleeding is the presence of excess asphalt on the surface of the pavement
which creates patches on the pavement. Excessive asphalt minimizes the resistance to skid by the

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pavement and when wet it can become slippery hence creating a safety hazard. The major factors
that result in bleeding include an improper application of seal coat, too heavy tack coat or prime,
using asphalt with low velocity, or an excessively high content of asphalt in the mix (Guo, 2013).
8.0 QUALITY CONTROL
During Design
The quality control procedures and measures begin during the early stages of pavement
production. These measures of quality control include the use of correct standards during the mix
design from numerous material standards to specific standards for HMA. Samples of asphalt
binder and aggregates should be tested for moisture during the design stage.
A Dynamic Shear Rheometer (DSR) should be used in the laboratory to investigate the elastic
and viscous behaviour of asphalt binders at high to medium temperatures. Low-temperature
measurements can be performed by the use of Bending Beam Rheometer (BBR). The test results
show that the 4-mm DSR can perform rheological tests at low temperature (Yuhong & Dan,
2017).
The Marshall Stability test should also be carried out in the laboratory of the asphalt samples so
as to determine the relationship between physical properties, exposure time, temperature,
ultrasonic velocity, and plastic flow for asphalt core samples. The expected laboratory results
regarding the relationship between other variables and the stability should be; space volume is
0.320, first ultrasound velocity is -0.064, resistance to flow should be -0.208, exposure time
should be -0.482, air dry unit volume weight should be -0.515, saturated unit volume weight
should be -0.522, second ultrasound should be -0.533, and temperature should be -0.887.
The mixing plant environment is also included in the measures of quality control since the plant
requires inspection for the raw materials which are being used to determine if they are being