CHAPTER 1

INTRODUCTION

1.1 Background

The general idea of this project is to produce and test foamed concrete (FC) in

the laboratory. Preliminary, it involves the finding of a mix proportion for foamed

concrete which will produce hardened concrete that can sustain dynamic load.

The Star Online News quoted Mr. Faizal Parish of the Global Environment

Centre (Peat Expert) that road construction on the peat soil area is unavoidable

phenomena in Sarawak because 95% of peat land in Sarawak is categorized as deep

peat which is more than 3m deep ( The Star Online, August 9, 2009). Therefore, this

research is aimed to introduce the composite structure of foamed concrete to be a

preferred material for sub base used in road construction on the peat soil. The

conventional method of using the geotextile and the bakau log is the common practice

for such construction on peat soil.

Composite concrete can be described as combined structure of different types of

concrete. In this project, combination of different mix of foamed concrete is examined

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in term of strength, volume and bonding in order to fulfill the required characteristics

of road sub base. Moreover, it will be compared to conventional method which is using

geotextile and bakau log. Thus, the required characteristics of the composite concrete

are determined through the experiments undertaken in this study.

1.2 Introducing Foamed Concrete

Foamed concrete is lightweight, free flowing material which consists

principally of a cement-based mortar or paste mixed at least 20% by volume air.

Foamed concrete is also known as aerated concrete, lightweight concrete or porous

concrete. The special characteristic of foamed concrete is it can be placed easily and

does not require compaction, vibration and leveling. It is first patented in 1923 and its

construction application as lightweight non- and semi- structural material are increasing

in the last few years.

1.3 Concept of Project

The concept of this project is to produce alternative way in replacing the

conventional way of constructing the sub base in road construction. Thus, it is proposed

to replace the conventional design which is using the bakau logs and geotextile with

anew design of using the composite model which combines the different mix of foamed

concrete.

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The concept of sub base construction using composite material is found similar

to the floating foundation concept. The significant American architect, John Wellborn

Root, who protects against settlement and the liquefaction of soft soil due to seismic

activity, has invented the foating raft foundation or floating foundation which is a type

of land-based foundation. It was a necessary innovation in the development of tall

buildings in the wet soil of Chicago in the 19th century. (Wikipedia, 2009)

For a floating foundation, the foundation has a volume where it is filled with

soil so that it would be equal in weight to the total weight of the structure. When the

soil is so soft, where even friction piles will not support the building load, the floating

foundation will be the solution. The floating foundation will make the building like a

boat that obeys Archimedes’ principle where it is buoyed up by the weight of the earth

displaced in creating the foundation. (Wikipedia, 2009)

Thus, it is similar to the function of the composite material that is proposed to

be as the road sub base on the peat soil. The composite material is expected to take up

the load from Down Crusher Run (DCR) and vehicles without sinking into the peat soil

which can affect the road structure in future.The conventional design of sub base in the

road construction is shown as in Figure 1.1 and Figure 1.2.

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Figure 1.1: Conventional design of sub base

Figure 1.2: Bakau arrangement prior to geotextile layering process

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Load

DCRGeotextile

Peat Soil

Soil embankment

Bakau (refer to Figure 1.2)

Geotextile layered on the bakau that arranged on the peat soil

Bakau logs

The role of bakau logs arranged prior to geotextile layering process is to

distribute the load subjected on the peat soil. Furthermore, it functions as the separating

the layer between Down Crusher Run (DCR) and peat soil. Other than that, they keep

the DCR together and avoid the DCR from falling into the peat soil and being wasted.

While the geotextile is used to take up the load from DCR. It also becomes the

separating layer between DCR and bakau logs arranged and peat soil.

Figure 1.3: Geotextile is layered on the excavated pathway

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Figure 1.4: Geotextile functions as the separator between aggregate and soil surface.

Thus, this conventional way is widely applied in the sub base construction on

the peat soil. Using the geotextile might cause longer construction period as it is

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imported product, mostly from China. The availability of the material might cause the

construction process to be delayed if the material is insufficient. Besides that, the

installation of geotextile will require a number of manpower which is uncertain in

productivity especially if there is raining as the geotextile installation will be

terminated. This will extend the period of the road construction which is not good to

the project progress. Other than that, the bakau supplies might be a problem nowadays

as it is not as many as before.

Therefore, to replace the conventional method, it is proposed to use the

composite materials which are the self compacting concrete and foamed concrete as the

replacement of the geotextile and bakau logs functions. Furthermore, these two types of

concrete are widely used in the construction industries nowadays. Thus, the availability

of the concrete material is not an obstruction to the construction.

The proposed design of sub base in the road construction is shown as in Figure1.5.

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Load

Peat Soil

Soil embankment

DCR

Composite Model

SCC

Foamed Concrete

Figure 1.5: Proposed design of sub base

Therefore, the proposed sub base made of composite model which is the SCC

and foamed concrete is able to replace the function of bakau and geotextile as shown in

Table 1.1.

Table 1.1: Conventional material functions substitution by composite material

Conventional

materials

Functions Foamed concrete

Bakau Distributing loading

Geotextile Take up load from DCR

Separating layer between

DCR and peat soil

1.4 Objectives of Project

The objectives of this project are:

a) To produce durable foamed concrete and test for its strength.

b) To examine the ability of structure to withstand dynamic load.

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1.5 Summary

The outlines of the structure of this project are summarized as below:

Chapter 1 is the introduction to the project carried out where the aim, objectives

and purpose of the project are stated in this chapter. In addition, general information of

the project will be included for preliminary research of the project. Other than that, the

outline of the structure of the following chapters in the project report will be included

in the summary of chapter 1.

Chapter 2 is the literature review of the project. The references made are due to

the aims and objectives requirement in order to support the methodology that will be

carried out to fulfill the objectives requirement. Thus, references are regarding to

journals, books and many more which will be done due to APA (American

Psychological Association) style.

Chapter 3 is about the methodology of the project which refers to the preferred

options and approaches used to achieve the objectives.

Chapter 4 is the results, analysis and discussions of the testing method is stated

in this chapter. Data collected from the testing method will be stated systematically,

analyzed and discussed due to the project requirement.

Chapter 5 is the conclusions and recommendations of the project. This is the

synopsis of the analysis and discussions from Chapter 4 which will be related to

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objectives of the project, whether it has satisfied the project requirements or not.

Recommendations will be stated in this chapter in order to improve the methodology

used so that better results can be achieved for future project research.

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