ABSTRACT
Controlled burning of rice husks at 6000C gives rice husk ash (RHA) which is properly produced to Pozzolan that is amorphous silica (SiO2) which can be added to cement for building applications. Cement was mixed with laterite in proportion of 10%, 20%, 30%, 40% and 50%. The concrete was cured for 7 to 28 days and also heat resistance was conducted. It was observed that 50% of cement provides the optimum strength with heat resistance of 10000C and above. Pozzolan was mixed with laterite in proportion of 10%, 20%, 30%, 40% and 50%. The concrete was cured for 7 to 28 days and also heat resistance was conducted, and it was observed that 50% of Pozzolan provides the optimum strength with heat resistance of 10000C and above. Pozzolan was also added to cement with laterite in proportion of 10%, 20%, 30%, 40% and 50%. The concrete was cured for 7 to 28 days and also heat resistance was conducted, and it was observed that 20% of Pozzolan added to cement provides the optimum strength with heat resistance of 10000C and above. The effects of different particle sizes of 75, 150, 212, 300, 425 and 600 Microns were tested using a compression test machine, it was indicated that 75 micron provides the optimum strength. Also a graph of average strength against particle size indicated 3.4 Nm-2 as the optimum strength at 75µm and 1.3 Nm-2 as the minimum at 150µm, which underlines the significance of the contribution of particle size to the desired strength. From the ash size distribution, the presence of grains of several different sizes was observed. The grains were weighed using a weighing machine and a graph of particle size against percentage plotted to determine the particle size distribution. This showed that rice husk ash (RHA) is coarse grain material. X – ray fluorescence (XRF) analysis was performed to determine the content of various chemical oxides in RHA, which indicated Si, Mn, K, Mg, P, Ca, Ru, Fe, Zn, Mg, Cr, Ti, Ni, Cu, Rb, Sr, Y, Zr, Eu and Ba. X – ray diffraction (XRD) analysis indicated the presence of SiO2 in the sample, which is amorphous silica. The results from this work show that adding Pozzolan to cement improves the strength, quality and quantity of concrete, which can be use for building applications.
TABLE OF CONTENTS
Declaration iii
Certification iv
Dedication v
Acknowledgements vi
Table of Contents vii
List of Tables x
List Figures xi
Abstract xii
CHAPTER 1: INTRODUCTION
1.1
Background to the Study 1
1.2
Statement of the Problem 5
1.3
Aim and Objectives 5
1.4
Scope and Limitations of
the Study 6
1.5
Significance of the Study 6
CHAPTER 2: LITERATURE
REVIEW
2.1 Related
Review 7
2.2 Hydraulic Cement 17
2.3 Non-hydraulic Cement 17
2.4 X-ray Diffraction 27
2.5 Theory of X-ray Diffraction 28
2.6 Scherrer Equation 30
2.7 X-ray Fluorescence 31
2.8 Theory of X-ray Fluorescence Spectroscopy 31
2.9 XRF Sources 34
2.10 Global Rice Production 34
2.11 Rice Husk Ash 35
2.12 Rice Husk Ash as an Active Pozzolan 36
2.13 Manufacturing Refractory Bricks 36
2.14
Silicon Chips 37
2.15 Tundish Powder in Steel Casting
Industries 38
2.16 Adsorbent for a Gold-Thiourea
Complex 38
2.17 Vulcanizing Rubber 38
2.18 Soil Ameliorant 38
2.19 Pozzolanic Reaction 39
2.20 Amorphousness 40
2.21 Fineness 41
2.22 Typical Amounts of Pozzolan in
Concrete by Mass of Cementing Materials 42
CHAPTER 3: MATERIALS
AND METHODS
3.1 Materials 43
3.2 Methods 52
3.2.1 Husk Collection 52
3.2.2 Ash and Concrete Production 52
3.2.3 Analysis 53
3.2.4 Procedure for XRD Analysis
53
3.2.5 Procedure for XRF Analysis
54
CHAPTER
4: RESULTS AND DISCUSSION
4.1 Strength
at Various Mixed Ratio of Cement 59
4.2 Strength
at Various Mixed Ratio of Pozzolan 62
4.3 Strength
at Various Mixed Ratio of Pozzolan with Cement 65
4.4 Strength
at Various Mixed Micron Sizes 68
4.5 Strength
at Different Particle Sizes 71
4.6 Particle
Size Distribution 74
4.7 Discussion 77
CHAPTER
5: CONCLUSION AND RECOMMENDATION
5.1 Conclusion 79
5.2 Recommendations 79
References 80
Appendices
83
LIST OF TABLES
4.1
Ash Composition by XRF 54
4.2
Chemical Composition of Cement 55
4.3
Chemical Composition of Laterite
Soil 56
4.4
Strength of Mixed Ratio of Cement 58
4.5
Strength of Mixed Ratio of Pozzolan 61
4.6
Strength of Mixed Ratio of Pozzolan
with Cement 64
4.7
Strength of Mixed Ratio of Different
Micron 67
4.8
Strength of Different Particle Size 70
4.9
Particle Size Distribution 73
LIST OF FIGURES
2.1 Deriving Bragg’s Law Using Reflection
Geometry and Applying 29
Trigonometry
2.2 Schematic of an X-ray Powder
Diffractometer 29
2.3 The Principles of XRF and the Typical
Detection Arrangement 33
2.4 Pozzolanic Reactions 39
3.1 Burning Furnace 44
3.2 Sieve Machine 45
3.3 Mould 46
3.4 Hammer Mill 47
3.5 Weight Balance 48
3.6 Electronic Balance 49
3.7 Compression Testing Machine 50
3.8 Kiln 51
4.1 Strength of Various Cement Mixtures
against Number of Days 59
4.2 Strength of Various Pozzolan Mixtures
against Number of Days 62
4.3 Strength of Various Pozzolan and Cement
Mixtures against
Number of days 65
4.4 Strength at Various Pozzolan Sizes (in
micron) against Number of
Days of Curing 68
4.5 Strength against Particle size 71
4.6 Particle Size Distribution 74
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Pozzolans are materials containing
reactive silica and alumina which on their own have little or no binding
property but, when mixed with lime in the presence of water, will set and
harden like cement. Pozzolans are important addictive ingredients in the
production of alternative cementing materials to Portland Cement, alternative
cements provide an excellent technical option to Ordinary Portland Cement (OPC)
at a much lower cost and have the potential to make a significant contribution
towards the provision of low cost building materials and consequently
affordable shelter. Pozzolans can be used in combination with lime and OPC.
When mixed with lime, pozzolans greatly improve the properties of lime based
mortars, concretes and renders for use in a wide range of building
applications. Alternatively, they can be blended with OPC to improve the
durability of concrete and its work ability, and considerable reduce its cost.
A wide variety of siliceous or aluminous materials may be pozzolanic, including
the ash from a number of agricultural and industrial wastes. The agricultural
waste, rice husk has been identified as having the greatest potentials as it is
widely available and, on burning, produces a relatively large proportion of
ash, which contains 90% silica (Snellings,
et al., 2012).
A general class of materials called
pozzlans have the potential to reduce substantially the cost of building. These
materials can be bland with lime (or Portland cement) to produce blended
cements which can replace pure Portland cement commonly used in building
materials such as concrete, masonry block, masonry mortar, bricks and other
construction units. The energy required to manufacture a lime – pozzolan cement
(LPC) is substantially less than that Portland cement; in some cases the
pozzolan requires no preparation. The cost associated with the production of
LPC is mainly due to the coal or oil used to produce the lime (Joseph, et al., 1989).
There are substantial advantages to
be gained in performance if well chosen pozzolans are used in cement-base
construction materials. They are found to improve quality of concrete, lower
heat of hydration, lower thermal shrinkage, increase water tightness, improve sulphate
resistance, improve seawater resistance, and reduce alkali-aggregate reaction.
Use of poor quality pozzolans in practice, with resultant failures, is a
principal reason why the confidence in the use of the materials is not high.
All pozzolanic materials when
combined in some manner with lime generally show the same qualitative behaviour
on both the fundamental and engineering levels. The differentiation between a
good and bad pozzolan is in the quality of improvement in engineering
properties such as strength and durability; economic consideration also play an
important role in this differentiation (Joseph, et al., 1989).
Pozzolan is a siliceous and
aluminous material which reacts with calcium hydroxide in the presence of
water. This forms compounds possessing cementation properties at room
temperature which have the ability to set even underwater. It transformed the
possibilities for making concrete structures, although it took the Romans some
time to discover its full potential. Typically it was mixed two to one with
lime just prior to mixing with water. The Roman port at Cosa was built of
pozzolan that was poured underwater, apparently using a long tube to carefully
lay it up without allowing sea water to mix with it. The three piers are still
visible today, with the underwater portions in generally excellent condition
even after more than 2100 years (Joseph,
et al., 1989).
Cement is a binder, a substance used
for construction that sets, hardens and adheres to other materials, binding
them together. Cement is seldom used on its own, but rather to bind sand and
gravel together. Cement is manufacture through a closely controlled chemical
combination of calcium, silicon, aluminium, iron and other ingredients. Common
materials used to manufacture cement include limestone, shells, chalk or marl
combined with shale, clay, slate, blast furnace slage, silica sand and iron
ore. These ingredients, when heated at high temperatures form a rock like
substance that is ground into a fine powder is called cement (Hewlett, et al., 2003).
Portland cement is the most common
type of cement in general use around the world as a basic ingredient of
concrete, mortar, stucco, and non-specialty grout. It was developed from other
types of hydraulic lime in England in the mid 19th century, and
usually originates from limestone. It is a fine powder, produced by heating
limestone and clay minerals in akiln to form clinker, grinding the clinker and
adding 2 to 3 percent of gypsum. Several types of Portland cement are
available.
The most common, called ordinary
Portland cement (OPC), is grey in colour, but white Portland cement is also
available. Its name is derived from its similarity to Portland stone which was
quarried on the lsle of Portland in Dorset, England. It was named by Joseph
Aspdin who obtained a patent for it in 1824.
However, his son William Aspdin is
regarded as the inventor of modern Portland cement due to his development in
the 1840s.Portland cement is caustic, so it can cause chemical burns,
irritation or, with severe exposure, lung cancer, and can contain some
hazardous components, such as crystalline silica and hexavalent chromium.
Environmental concerns are the high energy consumption required tomine,
manufacture, and transport the cement, and the related air pollution, including
the release of greenhouse gases (e.g., carbon dioxide), dioxin, SO2
and particulates.
The low cost and wide spread
available of the limestone, shale’s, other naturally-occurring materials used
in Portland cement make it one of the lowest-cost materials widely used over
the last century. Concrete produced from Portland cement is one of the world’s
most versatile construction materials (Dylan, 2014).
Rice husk are the natural sheaths
that form on rice grains during their growth. These are removed during the
milling of rice. Although these seem to have no commercial interest, however
they can be made useful through a variety of thermo chemical conversion
processes (Real, 1996). In a majority of rice producing countries, much of the
husks produced from the processing of rice is either burnt or dumped as a
waste. Rice husk is unusually high in ash compared to other biomass fuels; it
has close to 20% of ash as by product (Adyolov, et al., 2003). Ash is
92 – 95% silica, highly porous and light weight, with external surface area. So
with large ash content and silica content in the ash it becomes economical to
extract silica from ash which take care of ash disposal (Adylov, et al., 2003).
`Rice husk ash (RHA) is a term
describing all types of ash produced from burning rice husks which vary
considerable according to burning techniques. According to (Kalapathy, et al., 2000), the silica in the ash
undergoes structural transformations depending on conditions such as time and
temperature of combustion. At 500℃ to 700℃ amorphous” ash is formed and at
temperature greater than this, crystalline ash is formed (Joseph, et al., 1989). These types of silica
have different properties and it is important to produce ash of the correct
specification for the particular end use.
1.2 STATEMENT OF THE PROBLEM
The disposal of rice husks create
environmental problem that leads to the idea of producing pozzolan from rice
husk as a comparison to cement. This will improves the strength, work ability,
and durability of concrete.
1.3 AIM AND OBJECTIVES
The aim of this work is to compare
Pozzolan produced in Nigeria with Ordinary Portland Cement with the help of a
universal test machine and kiln which can be use for building applications.
OBJECTIVES
- Determine the ash composition
of rice husk (RH) at 600℃
- Determine the elemental
composition of Pozzolan sample produced in Nigeria by X – ray
fluorescence.
- Identify various types of
compounds present in Pozzolan, with its respective structure using X – ray
diffraction.
- Determine the elemental
analysis of Ordinary Portland Cement use
- Establish the elemental analysis of
laterite use
- Determine their optimum
strength of concrete mixed for various ratios.
- Determine
their heat resistance.
1.4 SCOPE AND LIMITATIONS OF THE STUDY
This work is mainly concerned with
pozzolan produced in Nigeria with respect to its strength, work ability,
durability, various elements and compounds present in pozzolan that can be
compare to ordinary Portland cement for building applications. Production of
rice to obtain rice husk may be the limitation of this work and establishment
of Pozzolan Company may also affect the actualization of this work.
1.5 SIGNIFICANCE OF THE RESEARCH
An in-depth research of pozzolan as
a comparison to cement for building applications will provide low-cost
materials in construction; develop low-cost building materials in order that
more of the lower-income sector of developing countries may obtain adequate
housing.
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