removing them from their leaching containers. These crystals could be due to the barrier formed during leaching. Fig 4.78: Surface of leached samples 28DB (left) and 6MB (right) Given that the solution was replaced regularly with fresh water, it was assumed that this re-crystallisation of C-S-H would be more prominent in the static samples as there is a higher concentration of ions. Therefore the TGA of exposure surface layers of the W-B series were examined and it was found that C-S-H amounts decreased up until 28 days after which the amounts of C-S-H seem to increase as shown in figure 4.79 which compares the weight loss curve for both W-28DB1 and W-3MB1. This is much earlier than was noticed in the semi-static tests and therefore suggests that removal of solution slows down the C-S-H reformation. This is only an indication as the weight loss could be due to the higher amounts of entrapped water in porosity. Fig 4.79: TG curves of W-28DB1 compared with W-3MB1 The increased weight loss as a result of higher C-S-H amounts could also be due to the increase in hydration or pore structure modification within the sample. To further investigate this the TGA profiles were compared for 0D samples with varying curing periods. Figure 4.80 shows TG curves for the original 0DB sample (cured for 42 days) alongside samples with the same composition but cured for 6 months, 1 and 2 years. Fig 4.80: TG curves of 0DB samples at different curing periods
removing them from their leaching containers. These crystals could be due to the barrier formed during leaching. Fig 4.78: Surface of leached samples 28DB (left) and 6MB (right) Given that the solution was replaced regularly with fresh water, it was assumed that this re-crystallisation of C-S-H would be more prominent in the static samples as there is a higher concentration of ions. Therefore the TGA of exposure surface layers of the W-B series were examined and it was found that C-S-H amounts decreased up until 28 days after which the amounts of C-S-H seem to increase as shown in figure 4.79 which compares the weight loss curve for both W-28DB1 and W-3MB1. This is much earlier than was noticed in the semi-static tests and therefore suggests that removal of solution slows down the C-S-H reformation. This is only an indication as the weight loss could be due to the higher amounts of entrapped water in porosity. Fig 4.79: TG curves of W-28DB1 compared with W-3MB1 The increased weight loss as a result of higher C-S-H amounts could also be due to the increase in hydration or pore structure modification within the sample. To further investigate this the TGA profiles were compared for 0D samples with varying curing periods. Figure 4.80 shows TG curves for the original 0DB sample (cured for 42 days) alongside samples with the same composition but cured for 6 months, 1 and 2 years. Fig 4.80: TG curves of 0DB samples at different curing periods
Wail%20Gashier%20Thesis.docx