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Decalcification of activated paper sludge – Fly ash-Portland cement blended pastes in pure water |
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| Affiliation: | 1. Department of Geography, Durham University, Durham DH1 3LE, England;2. Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08854, USA;3. Department of Physical Oceanography, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, MA 02543, USA;1. Department of Chemistry, University of the West Indies, Mona Kingston 7, Jamaica, West Indies;2. Department of Chemistry, Clemson University, 379 Hunter Laboratories, Clemson, SC29634-0973, United States |
| Abstract: | Decalcification in pure water of ternary Portland cement (TPC) pastes, containing thermally activated paper sludge and fly ash, has been evaluated from the leaching of Ca2+ in pure water at the temperature of 20 °C during 90 days. Monitoring of calcium loss showed that the leaching kinetics are controlled by diffusion. The degradation of the material over time is estimated from the calcium effective diffusivity. A similar study of plain ordinary Portland cement (OPC) pastes was carried out for comparison. The results showed lower effective diffusion coefficients of calcium in the case of the TPC pastes. This behaviour is related to its microstructure, which is denser than that of OPC as a result of the pozzolanic activity of both additions. |
| Keywords: | Leaching of calcium Pure water Ternary Portland cement (TPC) Plain ordinary Portland cement (OPC) Pore-size distribution Scanning electron microscopy (SEM) |
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