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Calcium aluminates can form complex salts in combination with different types of anions.Two series of calcium aluminates are known in cement chemistry: AFm and AFt phases, being respectively mono- or tri-substituted with a given divalent anion X (e.g. SO 2− 4, CO 2− 3, or hosting a divalent impurity such as SeO 2− 4 [3]...), or with two units of a monovalent anion, e.g. OH −, Cl − ...
When it reacts with concrete, it causes the slab to expand, lifting, distorting and cracking as well as exerting a pressure onto the surrounding walls which can cause movements significantly weakening the structure. Some infill materials frequently encountered in building fondations and causing sulfate attack are the following: [2] Red Ash
A concrete densifier is a chemical hardener that penetrates the concrete surface, reacting with the material to form crystals that fill the pores and increase surface density. This process significantly improves the concrete's resistance to wear, dusting, and chemical damage.
High-pressure chemistry is concerned with those chemical processes that are carried out under high pressure – pressures in the thousands of bars (100 kPa) or higher.High-pressure processes are generally faster and have a higher conversion efficiency than processes at ambient pressure.
To attempt to simplify and to stylize a very complex set of various reactions, the whole ASR reaction, after its complete evolution (ageing process) in the presence of sufficient Ca 2+ cations available in solution, could be compared to the pozzolanic reaction which would be catalysed by the undesirable presence of excessive concentrations of alkali hydroxides (NaOH and KOH) in the concrete.
Strength forms by hydration to calcium aluminate hydrates. They are well-adapted for use in refractory (high-temperature resistant) concretes, e.g., for furnace linings. Calcium sulfoaluminate cements are made from clinkers that include ye'elimite (Ca 4 (AlO 2) 6 SO 4 or C 4 A 3 S in Cement chemist's notation) as a primary phase. They are used ...
Concrete pipes for sewerage can be made either with full mass calcium aluminate cement concrete or with an internal liner of calcium aluminate cement mortar. Rehabilitation of man-accessible sewer infrastructures with 100% calcium aluminate mortar using one of the following placing methods: low pressure wet spray, spinning head wet spray, or ...
Superplasticizers (SPs), also known as high range water reducers, are additives used for making high-strength concrete or to place self-compacting concrete. Plasticizers are chemical compounds enabling the production of concrete with approximately 15% less water content. Superplasticizers allow reduction in water content by 30% or more. These ...