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CHAPTER V DISCUSSION
5.1. Result and Discussion of material Investigation
5.1.1. Investigate the Fine Aggregate to Obtain the Results.
1. Investigation of the organic matter content.
Investigate the organic matter content is important because the organic matter content can reduce the quality of the concrete. To know whether it is
possible to be used or not can be seen from the color of the sample. The relationship between the color and possibility of fine aggregate can be seen
from Table 5.1. Table 5.1 Relationship between the Color of the Solution and Organic
Mater Content
No. Color
Organic Mater Information
5 Light flaxen
Less organic matter content
Good to be used 8
Flaxen Rather much
organic matter content
Can be used
11 Dark Yellow
A lot of organic matter content
Not really good to be used
14 Dark Orange
A lot of organic matter content
Cannot be used 16
Dark Red A lot of organic
matter content Cannot be used
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5-1 After the sand washed using NaOH 3 and kept for 24 hours, the solution
is appropriate with the color of Gardner Standard Color No. 8 so that the sand can be used for the experiment.
2. Investigate the amount of mud in sand
Fine aggregate should not contain of mud until 5 greater than the density of dry oven. If the mud levels exceed 5, the fine aggregate should be washed
because the high value of mud can reduce the bind between fine aggregate and geopolymer paste. So, the quality of the concrete can be bad. The value of the
investigation can be seen in Table 5.2.
Table 5.2 Investigation of Mud in the Sand.
Investigation weight gram
Weight of sand A
99
So, the amount of mud in the sand can be calculated as follow:
with:
W= the amount of the mud in the sand A = the weight of sand after dried in the oven
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Based on SK SNI S-04-1989-F, fine aggregate cannot have the amount of mud more than 5. If the mud is more than 5 so that the fine aggregate
should be washed because the high content of mud will decrease the bond between sand and paste and it makes the quality will decrease.
3. Density and Absorption
The result of the density and absorption test of fine aggregate can be seen in table 5.3.
Table 5.3 Result of the Density and Absorption Test of Fine Aggregate
Information
Value
A
Dry Weight Sample
500 gram B
Weight Sample SSD
178 C
Weight of Sample from the Oven
482,13 gram D
Bulk Density = 2,712
E Bulk Density SSD =
2,812 F
Apparent Density = 3,001
G Absorption=
3,701
The fine aggregate is restrained in the sieve no. 4 4.75mm. The weight of the sample is 500gr. From the requirement, the density of the fine aggregate
for the normal concrete is around 2.4-3.2 grcm
3
. The density of this test is
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2.712 .
So the sand can be used in the geopolymer concrete. The absorption of the split is 3.701
4. Water Content
The water content test of fine aggregate is equal to 1.6635 . The calculation of the water content of fine aggregate can be seen in appendix A.3
5.1.2. Investigate the Coarse Aggregate to Obtain the Result
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