Abstract
pore solution. Diffusive migration of cesium as radioactive isotope is also considered. Electrical interaction of the migrating ions is taken into account. Example calculations demonstrate effects of parameter variations on distribution of precipitated calcite in the crack and on the composition of the outflowing solution, which can be compared directly with experimental results. Leaching behavior of sodium can be used to tune the model to experimental observations.
The calcite is mostly precipitated on top of the original crack surface and may under certain circumstances fill the crack. The produced thin layers of low porosity calcite act as a diffusion barrier limiting contact between cement and solution. Pore closure mechanisms in such layers are discussed. Implications for safety assessment of radioactive waste disposal are shortly mentioned. The model is also relevant for conventional uses of concrete.
| Original language | English |
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| Place of Publication | Roskilde |
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| Publisher | Risø National Laboratory |
| Number of pages | 99 |
| ISBN (Print) | 87-550-2612-5 |
| ISBN (Electronic) | 87-550-2613-3 |
| Publication status | Published - 2003 |
| Series | Denmark. Forskningscenter Risoe. Risoe-R |
|---|---|
| Number | 1143(EN) |
| ISSN | 0106-2840 |
Keywords
- Risø-R-1143
- Risø-R-1143(EN)
Cite this
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CRACK2. Modelling calcium carbonate deposition from bicarbonate solutions in cracks in concrete. / Brodersen, Knud Erik.
Roskilde : Risø National Laboratory, 2003. 99 p. (Denmark. Forskningscenter Risoe. Risoe-R; No. 1143(EN)).Research output: Book/Report › Report › Research
TY - RPRT
T1 - CRACK2. Modelling calcium carbonate deposition from bicarbonate solutions in cracks in concrete
AU - Brodersen, Knud Erik
PY - 2003
Y1 - 2003
N2 - The numerical CRACK2 model simulates precipitation of calcite from calcium bicarbo-nate solution (e.g. groundwater) passing through cracks in concrete or other cementitious materials. A summary of experimental work is followed by a detailed description of the model. Hydroxyl ions are transported by diffusion in pore systems in columns of cementitious materials. The hydroxyl is precipitating calcite from a flow of bicarbonate solution in a crack connecting the ends of a row of such columns. The cementitious material is simulated as calcium hydroxide mixed with inert material but with sodium hydroxide dissolved in thepore solution. Diffusive migration of cesium as radioactive isotope is also considered. Electrical interaction of the migrating ions is taken into account. Example calculations demonstrate effects of parameter variations on distribution of precipitated calcite in the crack and on the composition of the outflowing solution, which can be compared directly with experimental results. Leaching behavior of sodium can be used to tune the model to experimental observations.The calcite is mostly precipitated on top of the original crack surface and may under certain circumstances fill the crack. The produced thin layers of low porosity calcite act as a diffusion barrier limiting contact between cement and solution. Pore closure mechanisms in such layers are discussed. Implications for safety assessment of radioactive waste disposal are shortly mentioned. The model is also relevant for conventional uses of concrete.
AB - The numerical CRACK2 model simulates precipitation of calcite from calcium bicarbo-nate solution (e.g. groundwater) passing through cracks in concrete or other cementitious materials. A summary of experimental work is followed by a detailed description of the model. Hydroxyl ions are transported by diffusion in pore systems in columns of cementitious materials. The hydroxyl is precipitating calcite from a flow of bicarbonate solution in a crack connecting the ends of a row of such columns. The cementitious material is simulated as calcium hydroxide mixed with inert material but with sodium hydroxide dissolved in thepore solution. Diffusive migration of cesium as radioactive isotope is also considered. Electrical interaction of the migrating ions is taken into account. Example calculations demonstrate effects of parameter variations on distribution of precipitated calcite in the crack and on the composition of the outflowing solution, which can be compared directly with experimental results. Leaching behavior of sodium can be used to tune the model to experimental observations.The calcite is mostly precipitated on top of the original crack surface and may under certain circumstances fill the crack. The produced thin layers of low porosity calcite act as a diffusion barrier limiting contact between cement and solution. Pore closure mechanisms in such layers are discussed. Implications for safety assessment of radioactive waste disposal are shortly mentioned. The model is also relevant for conventional uses of concrete.
KW - Risø-R-1143
KW - Risø-R-1143(EN)
M3 - Report
SN - 87-550-2612-5
BT - CRACK2. Modelling calcium carbonate deposition from bicarbonate solutions in cracks in concrete
PB - Risø National Laboratory
CY - Roskilde
ER -