Comparative Study of Asphalt and Interlocking Pavement for Urban Roads

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Urban roads play a critical role in economic and social development because they support transportation, trade, and mobility. As cities expand, the demand for durable and cost-effective road surfacing materials increases. Two common pavement types used in many urban areas are asphalt pavement and interlocking concrete block pavement. Each pavement type has distinct structural, economic, and environmental characteristics. Understanding these differences is essential for selecting the most appropriate surfacing option for urban roads.

Asphalt pavement is widely used because it provides a smooth riding surface, supports heavy traffic, and allows quick construction. Engineers prefer asphalt for highways and major roads due to its flexibility and ability to deform under load without immediate cracking. However, asphalt deteriorates under high temperatures, heavy rainfall, fuel spills, and repeated traffic loading. Studies show that asphalt oxidation, rutting, and cracking reduce pavement lifespan, especially in regions with intense heat and poor drainage (Zhang et al., 2020).

Interlocking concrete block pavement (ICBP) has gained popularity in many developing countries. It is made from individual concrete blocks placed on a sand bed. The pavement distributes loads through interlock action and can withstand repeated loading without major structural failure. Additionally, ICBP allows easier maintenance because damaged blocks can be replaced individually. Researchers highlight that interlocking pavements perform well in areas with frequent utility repairs and drainage challenges (Knapton, 2016). The permeable version of interlocking blocks also supports stormwater infiltration, which reduces surface runoff.

Despite the strengths of both pavements, challenges remain. Asphalt requires frequent maintenance to address potholes and cracks. Interlocking blocks can shift when poorly installed or subjected to heavy truck traffic. Urban planners and engineers must therefore compare the performance of these pavements based on cost, durability, traffic suitability, maintenance, and environmental conditions. This comparative evaluation helps cities make better decisions and manage limited resources effectively.

1.2 Statement of the Problem

Urban roads in many Nigerian cities suffer from rapid deterioration. Potholes, surface deformation, erosion, and uneven surfaces disrupt mobility and increase vehicle maintenance costs. Asphalt pavements often fail prematurely due to poor workmanship, weak subgrade conditions, drainage problems, and high temperatures. Interlocking pavements are increasingly used as alternatives, but their performance varies depending on block quality, installation method, and traffic load.

Although both pavement types are widely used, there is limited comparative research that examines their performance under the specific environmental and traffic conditions found in Nigerian cities. Without reliable evidence, engineers and policymakers struggle to select the most suitable pavement for urban roads. This study seeks to fill this gap by comparing asphalt and interlocking pavements in terms of durability, cost, maintenance needs, and environmental impact.

1.3 Aim of the Study

The aim of this study is to conduct a comparative assessment of asphalt pavement and interlocking concrete block pavement for urban roads.

1.4 Objectives of the Study

The study seeks to:

1. Examine the structural characteristics of asphalt and interlocking pavements.

2. Compare the performance of both pavements under urban traffic and environmental conditions.

3. Evaluate maintenance practices and associated costs for each pavement type.

4. Assess user satisfaction and functional performance of the pavements.

5. Recommend the most suitable pavement type for selected urban road conditions.

1.5 Research Questions

The study answers the following questions:

1. What structural characteristics define asphalt and interlocking pavements?

2. How do these pavements perform under typical urban traffic loads?

3. What maintenance practices and costs are associated with each pavement?

4. How do road users perceive the performance of the two pavement types?

5. Which pavement is most suitable for urban road conditions?

1.6 Research Hypothesis

The study tests the following hypothesis:

H0: There is no significant difference in the performance of asphalt pavement and interlocking concrete block pavement.
H1: There is a significant difference in the performance of asphalt pavement and interlocking concrete block pavement.

1.7 Significance of the Study

This study is important for engineers, urban planners, and policymakers. First, it provides evidence that supports pavement selection based on performance and cost effectiveness. When cities select pavement types using scientific data, they reduce maintenance expenses and improve road quality. Second, the study helps contractors understand the conditions under which each pavement performs best. This supports better construction practices and enhances long term durability.

The study also contributes to academic knowledge in pavement engineering. It generates data that future researchers can use to explore advanced materials, climate-responsive pavements, or sustainable road technologies. Additionally, the findings benefit the general public because improved road conditions reduce travel time, enhance safety, and support economic productivity.

1.8 Scope of the Study

The study focuses on comparing asphalt pavement and interlocking concrete block pavement used on selected urban roads. It evaluates structural performance, maintenance history, user perception, and environmental factors. The study does not cover rural roads or highways because they have different load patterns. It also does not assess advanced pavement types such as polymer modified asphalt or reinforced concrete pavement.

1.9 Limitations of the Study

Some limitations may affect the study. Pavement performance varies with construction quality, traffic volume, and drainage systems. Therefore, results from selected roads may not represent all urban roads. In addition, access to maintenance records may be limited. Weather variations and soil conditions could also influence pavement performance. Despite these limitations, the study provides useful insights that support better pavement selection.

1.10 Operational Definition of Terms

Asphalt Pavement: A flexible pavement made from asphalt binder and aggregates.
Interlocking Concrete Block Pavement: A modular pavement made from precast concrete blocks that interlock to distribute load.
Durability: The ability of a pavement to resist deterioration over time.
Maintenance: Activities carried out to restore or preserve pavement condition.
Traffic Load: The weight and frequency of vehicles that use the pavement.

References 

Knapton, J. (2016). Concrete Block Paving. CRC Press.
Zhang, B., Zhang, Y., & Li, M. (2020). Mechanical performance and ageing behaviour of asphalt mixtures. Construction and Building Materials, 251, 118965.