| Popis: |
This paper presents the findings of a long-term study on the microstructure of Portland cement mortar specimens containing 5%, 15% and 35% limestone filler, as cement replacement, after exposure to a solution of magnesium sulfate at a concentration of 1.44% SO4, for 5 years at 5 °C. The findings are compared to results reported earlier, obtained from the same systems but after 1-year exposure. It was found that the deterioration due to thaumasite advanced with the increased exposure period and limestone content. Thaumasite solid solutions (Tss) formed as the dominant phases within the deteriorated cement matrix and at the paste-aggregate interface resulting in cracks and delamination. Thaumasite was also found as an inner product in various clinker grains. Interestingly, the control specimens, with no limestone filler, were found to exhibit cracks due to the formation of Tss, with atmospheric carbon dioxide being the most likely source for the carbonates. |
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