Water Absorption Test Essay

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Water absorption test
This test is to measure “effective porosity” of mortar structure. The type of specimen tested in this mixing of fly ash at 7, 28, 56 and 70 days. The specimens were oven dried at 100°C after reach curing age then cooled for further 24 hours in room temperature. The specimens were kept completely immersed in distilled water for 1 day. After a period of immersion, the mass of the wet specimens in air was measured. The water absorption of the specimen is calculated from the equation below:
Water absorption (%), WA = ((b_2-b_1))/b_2 x 100%
Where,
b_1= Mass of the oven-dried specimen (g) b_2= Mass of the wet specimen in air (g)

IV. RESULS AND DISCUSSION
After period of curing is reach, the specimens are taken out for conducted several test. Mortar
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The highest value of sorptivity is 10% fly ash replacement in 28 days and the lowest value is 0% of fly ash replacement at 7, 28 and 56 days. Overall, sorptivity values of all proportion of fly ash replacement are higher than 0% of fly ash replacement except in 70 days of curing. This represent that durability of mortar has increase after mixing with different proportion of fly ash. It can explain as fly ash react with calcium hydroxide in cement to form calcium silicate hydrate (C-S-H). With increase of C-S-H, the interconnected pore structures of mortar are filled of it. Fly ash reduces the permeability of concrete to water and gas provided the concrete is adequately cured [10].
Figure 7 indicate relative sorptivity value against curing age. It was almost same pattern as figure 8. It was observed that 10% of fly ash replacement in 28 days has greatest increases of sorptivity value which is 44% from 7 days. Other proportion mix like 5% and 15% also show highest changes of sorptivity value which are 18% and 25% respectively. This is showed that durability increases in early age of all mixtures.
IV.V Water

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