Pavement

CHAPTER I

INTRODUCTION

1.1 Background.

In the past forty years, Malaysia has developed rapidly into an industrialized country, producing a variety of products. There was unparallel amount of development in infrastructure especially in road network system. There are approximately 73 403 km of roads with a staggering 78% of paved road and the remaining are soil/earth or gravel roads (K.P.Chong, 2004). This system has served to great importance to the development of Malaysia. However, many of these roads have reached a point where it needs maintenance to preserve it at an acceptable level. Therefore, a pavement rehabilitation process is needed urgently to carry out maintenance on these roads.

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Rehabilitation is a process to recover the condition of the defected roads. Asphalt overlays, mill, replacing and reconstruction are among the technique used to rehabilitate the existing asphalt. In mid 80's, the recycling technique was introduced in Malaysia (K.P.Chong, 2004). Since the main concept of the technique is recycling, it became more preferable and popular. Today there are two types of recycling techniques namely hot recycling and cold recycling.

1.1.1 Treatment

In order to maintain all the road condition, a large sum of money has to be invested. Therefore it is essential to adopt the most cost effective technique of rehabilitation.

There are several types of treatment that can be applied in treating the distress pavement. Each has their own advantages. Among them are Cold-in-Place-Recycling, and Hot Mix Overlay. This project, we will focus on Cold-in-Place-Recycling.

1.1.2 Cold-in-Place-Recycling (CIPR)

Cold in place recycling is one of the techniques used in pavement rehabilitation. This is an innovative road reconstruction process and cost-effective compared to any other traditional reconstruction pavement method.

Generally, CIPR project requires less time to complete compared to other conventional grind and pave method. Since it requires lesser time to finish, it minimizes the problem to the public that uses the road and to businesses that may rely on that road for their traffic.

However, this technique can only be used on roads with good pavement structure and drainage system. It is usually used in rehabilitate surface distress such as minor rutting, cracking, and raveling. If the existing pavement has fatigue cracks and severe rutting, then this technique is not suitable to be used. Examples of minor surface distress are shown in Figure1.1 to Figure 1.4 in the following page.

This technique eliminate the need for new material in order to rehabilitate, it uses the existing asphalt by recycling it. Through this technique, the asphaltic pavement was milled and the reclaimed materials were blend with stabilizing agents and aggregate. As a result, this process are cost saving and produces less waste.

CIPR works by milling the distressed road and mixing them with water in the recycler's mixing chamber. Later on, a stabilizing agent is added either in liquid or powdery form. After that, the material receives an initial pass from a roller and later profiled by a motor grader before being compacted by a vibratory roller. A complete diagram of a recycling train is shown below:

1.1.2.1 Advantages of CIPR

There are a lot of advantages in using CIPR method for rehabilitation of pavement. Among them are:

* Environment - Full use of material of existing pavement

* Cost effective - Existing pavement structure materials are recycled to minimize addition of imported material. Comparison of technique and cost are shown below.

Table 1.1 Comparative Costs (Source: Wirtgen, 1998)

Comparative Cost

Option Cost per m2 (RM)

1. Reconstruct pavement 111.88

2. Asphalt Overlay 77.52

3. Cold-In-Place-Recycling

 Cement

 Bitumen Emulsion + Cement

 Foamed Bitumen + Cement

71.67

45.87

40.74

* Quality - High quality mixing of in-situ material and electronic aid pumping system for better mixing.

* Structural Integrity - CIPR produces thick bound material thus will not contain any weak interfaces between thinner pavement layers.

* Minimal disturbance on subgrade - Less disturbance on poor subgrade due to single pass operation of CIPR.

* Shorter Construction Time.

* Traffic Safety - Minimal obstruction of traffic since recycling train can accommodate the width of one lane therefore the process will be fast and the road can be opened to traffic faster.

1.2 Objective

The objective of this project is to:

i) Evaluate the performance of different stabilizing agent (lime, cement, bitumen emulsion and foamed bitumen) under UCS test.

ii) To understand the effect of each stabilizing agent in cold in place pavement recycling.

1.3 Scope

A literature review was conducted on the role of stabilizing agent, their characterization and recent development with emphasis on CIPR applications. Four different types of stabilizing agent is used - that is, cement, lime, bitumen emulsion, and foamed bitumen.

All four stabilizing agent is added with different percentages so as to determine their effects towards the strength