page_title: Concrete degradation
section_title: Leaching
hierarchical_section_title: Concrete degradation / Chemical damage / Leaching
caption_attribution_description: English: Calthemite flowstone with Iron Oxide deposited along with calcium carbonate (CaCO3). A secondary deposit derived from concrete.
context_page_description: Concrete degradation may have various causes. Concrete can be damaged by fire, aggregate expansion, sea water effects, bacterial corrosion, calcium leaching, physical damage and chemical damage. This process adversely affects concrete exposed to these damaging stimuli.
context_section_description: When water flows through cracks present in concrete, water may dissolve various minerals present in the hardened cement paste or in the aggregates, if the solution is unsaturated with respect to them. Dissolved ions, such as calcium (Ca²⁺), are leached out and transported in solution some distance. If the physico-chemical conditions prevailing in the seeping water evolve with distance along the water path and water becomes supersaturated with respect to certain minerals, they can further precipitate, making calthemite deposits (predominately calcium carbonate) inside the cracks, or at the concrete outer surface. This process can cause the self-healing of fractures in particular conditions.
caption: Calthemite flowstone stained orange from rusting reinforcing (iron oxide) being deposited along with calcium carbonate
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