Coarse Aggregate Material Testing
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Hatmoko 2009 with the title of the research is “The Compressive Strength of
Geopol ymer Concrete Made with Bagasse Ash and Metakaolin”
The amount of specimen that will be done is 18 specimens with the kind of variant such as shown in table 4.1
Table 4.1 The Amount of Specimens
Age of the Experiment Metakaolin : Silica Fume
Amount of the Specimens
25:5 50:5
75:5 14 Days
3 3
3 9
28 Days 3
3 3
9 The difference between geopolymer concrete and conventional concrete is in
the cement. Conventional concrete use cement while the geopolymer concrete replaces the cement with geopolymer pasta to bind the entire component.
Step to make geopolymer concrete: 1.
Prepare of Pozzolan The pozzolan in this experiment is metakaolin and silica fume. The
metakaolin is a material comes from the combustion of kaolin. Metakaolin will be burn in 800°C and after that it will be sieved in
sieves 100mm. Both metakaolin and silica fume are prepared according to the proportion that already planned.
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2. Step to Make an Activator
a. The molarity of NaOH that will be used is 40gmol. To make
a concentrated solution of NaOH 12M, the composition will be 12x40 = 480 grams of NaOH. After that NaOH will be
diluted with 1 liter of distilled water. Stir the NaOH mixed with the distilled water and wait until the solution is cold.
b. The solution of NaOH that already made will be mixed with
Na2SiO3 with the ratio of 2:1 and stir until completely mixed. Let stand the activator solution for 24 hours at room
temperature 3.
Prepare the rigid plastic and cover it with oil. Put the plastic on the wall of inside mold.
4. After 24 hours the Alkali activator will be mixed with Pozzolan and
the aggregate. The ratio of aggregate and alkali activator will be 3:1. The composition of the metakaolin will be 25, 50 and 75 of the
concrete weight and the composition of the silica fume will be 5 of the concrete weight.
5. After all of the mixture is mixed properly, do slump test for the
geopolymer concrete mix. 6.
After that, geopolymer concrete was put into the molds and after reach 13 of the height of mold pound 25 times. Pour the geopolymer
to the mold again, after reach 23 of the height of mold pound it again
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for 25 times. Pour the geopolymer until full and then flatten the surface of it.
7. Put the concrete mix with the mold into the the oven at 80°C for 24
hours. 8.
After that, geopolymer concrete is released from the mold and put into the oven at 23°C over the life of the testing that has been
established 14 and 28 days.