�
UTILIZATION OF COAL COMBUSTION WASTE (FLY ASH)
FOR GEOPOLYMER CONCRETE AS GREEN CONCRETE
Nugroho Arie Putranto
PT. Indah Karya
(Persero)
[email protected]
|
KEYWORDS Coal combustion waste, Fly ash, Geopolymer, Concrete ARTICLE INFO Accepted:
January, 26th 20222 Revised: February, 13th 2022 Approved: February, 14th 2022 |
ABSTRACT The
use of Portland Cement as a paste in conventional concrete is still often the
primary/favourite choice in civil engineering construction. In time, cement
production will cause harm to the environment, especially in the production
process, and the availability of natural raw materials in cement production
will dwindle. Therefore, it is necessary to find an innovative alternative to
replace cement utilization. From the test matrix that has been carried out,
it can be concluded that the waste from burning coal (fly ash), can be used
as a substitute for Portland cement, and also at the composition of 16 moles
� the ratio of sodium silicate to sodium hydroxide of 1.5 has a strong
quality much better compression than the composition when using a 100%
Portland cement mixtureFrom the test matrix that has been carried out, it can
be concluded that the waste from burning coal (fly ash), can be used as a
substitute for Portland cement, and also at the composition of 16 moles � the
ratio of sodium silicate to sodium hydroxide of 1.5 has a strong quality.
much better compression than the composition when using a 100% Portland
cement mixture. |
INTRODUCTION
Basically, this research has the aim of utilizing Soda Ash waste
into usable goods that can be used as a substitute for the use of Portland
Cement as a building material for construction and other infrastructure
development.
So far, concrete is known as the most popular building material (Meyer,
2005). This is because the basic
ingredients are easily found and relatively cheap, and the technology used in
the manufacturing process is relatively simple. However, lately the use of
concrete has been receiving criticism more often, particularly from among those
who care about the environment (M�ld�r,
n.d.). The spotlight of attention is the
emission of gases such as carbon dioxide (CO2) produced from the calcination
process of limestone and combustion in cement production processes, requiring
high temperatures in the production.
On the other hand, as the demand for construction materials such as
concrete rises, the demand for cement raw materials also increases. Growth in
Indonesian market show that cement consumption for the first half of 2008
increased by 21.1 percent from 15.5 million tons as of June 2007 to 18.8
million tons in June 2008. It is estimated that the cement consumption until
the end of this year will reach 20.4 to 21.3 million tons. Production of one
ton of portland cement will produce one ton of CO2 which is released into the
atmosphere, which will in turn lead to the effects of global warming. CO2
contribution to global warming itself is approximately 65% (Davis
& Gertler, 2015). Increased production of cement
will increasing the amount of CO2 released into the atmosphere so that it will
also accelerate the global warming process (Huntzinger
& Eatmon, 2009).
In allusion to the contribution of the cement industry of to the
total CO2 emissions, then we need to exert more efforts to reduce gas
production rates that trigger a global warming, due the fact that the percent
contribution of CO2 will continue to increase along with the increasing amount
of cement production. Therefore it is important to find ways to replace cement
in the concrete manufacturing process, or totally replace it with another
material that is more environmentally friendly.
In this study fly ash is used with the following considerations:
1.
Uses materials or waste materials resulting
from coal combustion Geopolymer concrete is
environmentally friendly because it uses waste materials that can pollute the
environment and reduces CO2 emissions from cement production (Davidovits,
1991).
2.
Reduces the amount of cement consumption, so that geopolymer concrete is
expected to have cheaper production costs compared to conventional concrete in which the amount of CO2 emissions
released into the air which is comparable to
the amount of cement produced (Davidovits,
1991). This circumstance
was
what mostly encouraged us to find alternative materials to
replace cement in concrete making.
3.
Fly Ash is already a
familiar material in the manufacture
of concrete.
METHOD RESEARCH
The type of research carried out is by conducting trial error on
each material composition. The test is carried out in a concrete laboratory and
carried out an analysis of the sample as a whole.
Materials
a.
Fly Ash
The researcher use material from coal
combustion (fly ash) as
cement replacement material. The fly ash used is from
Paiton.
b.
Portland Cement
In this case
the cement is used as a comparison between conventional concrete and geopolymer
concrete
c.
Sand
d.
Gravel
e.
NaOH (Sodium Hidroxyde)
Sodium
hydroxide is largely sold in the market. The form is solid and white and
appears slightly dewy on the surface. Sodium hydroxide absorbs water and carbon
dioxide from the air. In the event of direct contact with the skin, it will
give heat and burns (causing skin irritation). In the manufacture of geopolymer
concrete, sodium hydroxide is used as an alkaline activator (Hardjito,
Wallah, & Rangan, 2004). As an alkaline activator, sodium hydroxide is used to react the
elements Al and Si that are contained in the fly ash so as to produce a strong
polymer bond
f.
Na2SiO3 (Sodium Silicate)
Sodium silicate gel is like as a blob of glass with
a greenish color.� If left in the open
air, this gel will eventually harden and look like
glass. Therefore, sodium silicate is often referred to as water glass. Sodium
silicate has a viscosity (thickness) between 0.4 - 600 000 cps (centi poise).
This gel also has a pH between 3-9. In making this geopolymer concrete, sodium
silicate has the function to accelerate the polymerization reaction occurring
within the concrete. (Hardjito et
al., 2004).
Synthesis�������������������������������������������������������������������������������������������
Techniques Data analysis is done by making a
matrix of specimens with various compositions of mixtures of materials (Chung, 1974) (can be seen in
the table below) and testing according to the duration of the sample life of
each mixture.
a.
Preparation of the research matrix specimen:
Table 1. Research
Matrix Specimen
|
Type |
Test
Day
7 |
Test
Day
14 |
Test
Day
28 |
Test
Day
56 |
XRD |
Total |
|
12 mol � ratio.0,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
12 mol - ratio.1,0 |
3 |
3 |
3 |
3 |
3 |
15 |
|
12 mol - ratio.1,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
12 mol - ratio.2,0 |
3 |
3 |
3 |
3 |
3 |
15 |
|
12 mol - ratio.2,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
14 mol - ratio.0,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
14 mol - ratio.1,0 |
3 |
3 |
3 |
3 |
3 |
15 |
|
14 mol - ratio.1,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
14 mol - ratio.2,0 |
3 |
3 |
3 |
3 |
3 |
15 |
|
14 mol - ratio.2,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
16 mol - ratio.0,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
16 mol - ratio.1,0 |
3 |
3 |
3 |
3 |
3 |
15 |
|
16 mol - ratio.1,5 |
3 |
3 |
3 |
3 |
3 |
15 |
|
16 mol - ratio.2,0 |
3 |
3 |
3 |
3 |
3 |
15 |
|
16 mol - ratio.2,5 |
3 |
3 |
3 |
3 |
3 |
15 |
b. Molar concentration used in the research were 12 mol, 14 mol, dan 16 mol
c. Composition of sodium silicate to sodium hydroxyde are 0,5 ; 1,0 ; 1,5 ;
2,0 ; 2,5
d. Sand and gravel used for making samples are treated the same for all
variations
e. First shaped test specimens using mortar 50mm x 50mm.
f. Specimen test at age� 7, 14, dan 28
Data collection is collected from the results
of trials on the list of matrix data so that conclusions can be made which
composition is the best that can be applied.
Analysis
In carrying out the analysis, the author uses
several references or methods of conducting sample tests/trials based on the
following standards:
1.
Fine Aggregate
a)
Weight of sand (ASTM
C128-93)
b)
Humidity of sand (ASTM C 556-89)
c)
Water infiltration in the sand (ASTM C128-93)
d)
Weight of sand volume (ASTM
C 29 / C29M � 91)
e)
Cleaning of sand on organic materials �(ASTM
C 40 � 92)
f)
Cleanliness of sand to mud (ASTM
C 117 � 95)
g)
Analysis of the filter (ASTM C136 � 95A)
- Coarse
Aggregate
a)
Humidity
of gravel (ASTM
C 556-89)
b)
Weight of gravel (ASTM
C 127 � 88 Reapp 93)
c)
Water infiltration in the gravel (ASTM
C 127 � 88 Reapp 93)
d)
Weight of gravel volume (ASTM
C 29/C 29 M � 91a)
e)
Cleanliness of gravel to mud (ASTM
C 117 � 95)
f)
wear tests of coarse aggregate (ASTM
C 131 � 89)
g)
Analysis of the filter (ASTM
C1366 � 95A)
- The
Specimens
a)
Slump test of concrete (ASTM
C 143 -78)
b)
Concrete Porosity (AFNOR
NF B 49104)
c)
compressive strength of concrete (ASTM
C 823 � 75)
d)
splitting tensile strength (ASTM
C 496� 94)
