MECHANICAL for the industrial usage. Simultaneously test do

 

MECHANICAL
BEHAVIOUR OF FLY ASH STABILIZED MUD CONCRETE BLOCKS IN COMPARISON WITH BRICKS,
CEMENT BLOCKS, AND CSEB BLOCKS

 

B.G.J. Nipuna

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Department of civil enginnering,

University Of moratuwa

Prof R.U. Halwatura

Department of civil enginnering,

University Of moratuwa

Abstract:
Sustainable construction materials are very interested in modern world. Fly ash
stabilized mud concrete blocks are under research stage to provide industry as building
construction material. The main components of fly ash stabilized mud concrete
blocks are soil, fly ash, Sault, sodium hydroxide. Some researches were done to
find out optimum proportion of these material for blocks. This research focused
on the mechanical behaviour of mud concrete blocks. Tests basically do with the
changing bond thickness, mortar type and bond patterns. Compressive loads add
to the wall panel construct with mud concrete blocks and these values compare
with the test values of bricks, cement blocks, CSEB blocks wall panels. Observe
crack patterns and study what to develop for the industrial usage.
Simultaneously test do for the bricks, cement blocks, CSEB blocks wall panels
also to compare the behaviour. Study the blocks dimensions for the optimum
section and mortar quality is main objectives of this research. Soil can be
considered as very old building construction material. The process of Develop
that material and provide as a sustainable building construction material is
very vital in many ways such as environmentally and economically. This paper
present test values for the wall panels constructed with different materials
and the best mortar and bond pattern for the wall panel construct form fly ash
stabilized mud concrete blocks

Keywords:
Mud concrete blocks; Bricks; Cement Blocks; CSEB blocks; Stabilization; Fly ash
stabilization; Wall panel;  Mechanical
behaviour;

 

1.   
Introduction

People
started to construct buildings from soil at very early stage. After that step
by step it changed to cement and concrete. But now the tread is to use more sustainable
building construction material for the constructions. Among sustainable
building construction materials soils plays a great role. Many researchers were
done to find out method to use material like soils in optimum way to use
required quality. Soil stabilization, Mud concrete blocks, Geo polymer concrete
are some examples for them.

            Soil modification is the process of
addition of a modifier to a sol to improve its strength and durability. The use
of alternative cheaper materials as stabilizers will greatly enhance the
production of blocks with the desired properties at low cost. It will also
drastically reduce the cost of production and consequently the cost of
construction works (Lanka. S,1999) many researches were done to
find out stabilization materials for soils. Alkaline activation effect is the
most popular method. In many develop countries like Sri Lanka is need to find
out sustainable and economical materials for the construction. Every county
must have to pay attention not to the development but for sustainable
development.

Mud
concrete is similar kind of earth stabilized block build by mixing cement and
soil to build block. The mud in this mixture plays a great role as a filler
material and to develop the workability of the mixture. However, the role of
cement in low quantities is to stabilize the soil Mud is one of humankind’s
oldest and most universally used construction materials. Even at the dawn of
humanity sustainable development. So to study and do researches in this stream
is very vital.

Mud concrete blocks

Mud
concrete blocks plays a great role in sustainable building construction
material. It is first developed and introduced to the construction field in Sri
Lanka by university of Moratuwa. Basically concrete consists with Concrete is
cement, sand, metal and water. Instead of using these materials researchers
found a mixture consists with Soil, stabilizing agent, Water mixture.  Mud concrete block which has made by
replacing sand and metal of concrete by fine and coarse aggregates of soil. The
strength of mud concrete blocks is depend on the proportion of sand and gravel
mixture. Cement is also used when preparing mud concrete blocks as a stabilizer
in very low quantities.(Udawattha & Halwatura 2016)

First
researchers invented mixture of clay, soil, water, course and fine sand with
some amount of soil in 2015. In 2017 researchers were found that composition of
soil, water, salt, and sodium hydroxide. Mud concrete block has a self-compacting
nature. Self-compaction is a
method of compacting by using its own weight. Porosity cause for the strength of the block
and the compaction level cause for the porosity. Low porosity means high strength. To reduce porosity we have to
introduce compacting technology or materials to improve compaction. (Engineering
n.d.)Thermal properties also very important
characteristics of construction materials. To achieve self-compacting quality,
water content is very important. But
higher water content will lead to reduction in compressive strength of the mud
concrete blocks. So it is very important to maintain considerable water content
without affecting to the strength of mud concrete block and self-compacting quality.
The optimum proportion for this 
experiments suggested a water content has to be maintained in range of
18% – 20%.(Engineering n.d.)

Wall panel
can build by using md concrete blocks with the cement mortar or another mud
mortar. From these two side we have to first initiate the best binder for mud
concrete blocks wall panels. If we maintain precise sand, gravel, water content
and good compaction level we can achieve fare face which will reduce the
finishing cost in wall construction. Compared with other wall materials such as
concrete blocks and burnt bricks mud concrete blocks have good natural colour
and aesthetic beauty.  In load bearing
mud concrete blocks get the highest place. Durability and thermal comfort,
keeping the low embodied energy is added advantages of mud concrete blocks. (Udawattha, C. & Halwatura, R., 2016). Mud
concrete blocks will become very popular in construction world in future.
Because of the easy production process, new appearance, low cost constructions
and the lower energy consumption will cause for the popularity of mud concrete
blocks in near future..(Lanka 2015)

 

 

CSEB Blocks

CSEB
blocks stands for compressed stabilized earth blocks. CSEB blocks are made from
sand, soil, 10% cement. Bricks stacks and cure 21 days. The cement made the
bond between sand stabilizing bricks. The Compaction add required density to
the blocks. Compressed stabilized earth blocks are behave more likely to the
bricks.

Soil Stabilization

Stabilization
means the process of blending and mixing materials with soil to achieve required
soil strength and durability. The main weakness of earth as a building
material lies in its low resistance to water. Overhanging eaves and verandas
help considerably, but tropical rains of any intensity can damage unprotected
walls. Because of the clay fraction, which is necessary for cohesion, walls
built of unsaturaded soil will swell on taking up water and shrink on drying.
This may lead to severe cracking and difficulty in getting protective
renderings to adhere to the wall (Jegandan,
Liska, Osman, & Al-Tabbaa, 2009).

Stabilizing process can do with
include blending soils to have a desired gradation or mixing commercially
available additives that may change gradation, change strength and durability,
or act as a binder to cement the soil.

Final out comes of the
stabilization process are

·        
To reduce plastic index

·        
Increase the durability

·        
Increase the strength

·        
increased durability

·        
Give a good working platform for any
whether conditions

 (Force n.d.)

Various Methods of Soil
Stabilization

Mechanical, cement, lime,
bituminous, thermal & electrical methods are some example for soil
stabilizing methods. In mechanical stabilizing method change the gradation of
soil. Mixing soil with cement is also a stabilizing method. Soil can be
stabilized by adding lime to the soil and the method is called lime
stabilization. This method is widely used in clayey soil. Using asphalt also
good stabilizing method. But due to the low viscosity it is not easy to use and
not cost effective. Thermal Stabilization is also good stabilizing method and
it can be done either from extreme heating to extreme cooling of the soil.
Chemical stabilization is done by using chemicals functioning as compaction
aids, water repellent, binders. The reaction between the chemical additives and
the soil particles can bind the soil grains by the strong network. Using
chemical stabilizing agents, the soil produced with better quality is compared
with the mechanical and physical techniques, (Zaliha et al. 2013)

 

Fly ash

Fly ash is
the remaining fine particle come after the coal combustion. Fly .It consists of
very fine particles of

·        
Silicon Dioxide (SiO2)
(Amorphous & Crystalline)

·        
Aluminium Oxide (Al2O3)

·        
Iron Oxide (Fe2O3)

·        
Calcium Oxide (CaO)

Fly ash
use in various type of purposes in construction field. Fly ash uses in Concrete
,production of Cement Clinkers, as a soil stabilizing agent, Mineral Filler in
Bituminous Concrete, etc. (Trivedi et al. 2013)

Fly ash
can classified in to two categories called F type and C type based on chemical composition.
Class F fly ash is produced by burning anthracite and bituminous coal, and
class C fly ash is produced by burning lignite and sub-bituminous coal. Amount
of calcium and silica composition is  the
main difference between F and C. Class C fly ash, in addition to having
pozzolanic properties, also has some cementitious properties and it has been
successfully used as part of the binder in stabilized base applications.(Degirmenci et al. 2007)

Fly ash as a stabilizer

Chemical
and physical properties of soil may change according to the original soil
properties by adding fly ash. Following properties changed when adding fly ash
to the soil.

·        
Soil texture,

·        
Bulk density,

·        
Water holding capacity

·        
Soil pH

 

Based on
the source fly ash may show alkaline or acidic characteristics. It could be
used to buffer the soil pH. The hydroxide and carbonate salts give fly-ash the
capability of neutralizing the acidity in soils. (Trivedi et al. 2013)

 

 

Alkaline Effect

Many researches were done to study the alkaline effect. In
previous research, it has been observed that the alkaline activation of
materials containing silica and alumina can be used as an alternative to cement
in construction.(Glendinning et al. 2011)

Alkaline activation is a chemical process in which a powdered
aluminosilicate such as fly ash is mixed with an alkaline activator to make a
paste capable of setting and hardening in a fairly short period of time. The
properties like strength, shrinkage, and acid and fire resistance of the
resulting materials depend upon the type of the aluminosilicate used and the
variables of the activation process.

Alkaline activation of fly ash is environmentally friendly
binders having similar properties or increasing the characteristics of
conventional materials.(Palomo & Fernández-Jiménez 2011)

Sodium
Hydroxide additive

The main advantage of sodium
hydroxide is that it can use as a great compacting It provide  greater density for the same compacting effort
when it reacts with water.(Zaliha et al. 2013)

In the
process of strength gain activated system NaOH concentration plays a very
important role. To increase strength have to increase NAOH concentration. (Cristelo, Glendinning, Miranda, et al. 2012)

Methodology

The main
aim of this research is to find out the possibility of inventing a new “mud
block” and study the mechanical behaviour of them to develop for industry
usage. To develop mud concrete blocks which has required strength for load
bearing walls while satisfying less weight and low cost together with simple
manufacturing process.

To find
out optimum mortar combination for bond and study the crack patters 

The
following methodology will follow in this research.

·        
Construct Mud concrete blocks with pre
designed proportions

·        
Collect other materials bricks, cement
blocks, CSEB blocks for the wall panel construction

·        
Construct wall panel with 3 mortar mix
proportions.

·        
Tests wall panels to check the mechanical
behaviour

·        
Study the crack patterns and record
values

·        
Compare them with the other material type
values

 

Conclusion

Various researches were conducted
to improve the behaviours of bricks,   Mud concrete blocks plays a great role in
sustainable construction material. This researched based on mechanical
behaviour of mud concrete blocks wall with the comparison to the brick wall
panels, CSEB blocks wall panels. Of Also researches here basically testes the
crack patents and maximum compressive strength bond pattern but proper research
on mechanical behaviour of fly ash stabilized mud concrete blocks in comparison
with bricks, cement blocks.

Acknowledgement

The
help received from the department of Civil Engineering in University of
Moratuwa highly appreciated. Professor Halwathura and Cr chameera udawattha
your contribution for this research is highly appreciated.

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