| dbo:abstract |
The alkali–carbonate reaction is an alteration process first suspected in the 1950s in Canada for the degradation of concrete containing dolomite aggregates. Alkali from the cement might react with the dolomite crystals present in the aggregate inducing the production of brucite, (MgOH)2, and calcite (CaCO3). This mechanism was tentatively proposed by Swenson and Gillott (1964) and may be written as follows: Brucite (Mg(OH)2), could be responsible for the volumetric expansion after de-dolomitisation of the aggregates, due to absorption of water. The alkali–carbonate reaction is also catalyzed by the soluble NaOH produced by the reaction of Na2CO3 with Ca(OH)2 (portlandite) present in the hardened cement paste (HCP), therefore perpetuating the reaction indefinitely as observed by Fournier and Bérubé (2000) and Bérubé et al. (2005). The sum of the two above mentioned reactions leading to the ultimate production of brucite and calcium carbonate can be written as follows: The alkali-carbonate reaction is much less understood than the alkali-silica reaction. Both reactions share in common the continuous regeneration of the sodium hydroxide (NaOH) after the reaction of soluble sodium carbonate or sodium silicate with calcium hydroxide, Ca(OH)2. However, impure dolomitic aggregates also often contain clay impurities, and small amounts of pyrite (FeS2) and organic matter. The alkali-carbonate reaction could therefore also simply hide an alkali-silica or an alkali-silicate reaction. Anyway a chemical coupling between ACR and ASR cannot be ruled out. (en) La reazione alcali-carbonato (Alkali-carbonate reaction o ACR) è una reazione alcali-aggregato che determina il deterioramento della durabilità del calcestruzzo a causa della presenza aggregati calcarei dolomitici. (it) De alkali-carbonaat-reactie is een anorganische reactie waarvan verondersteld wordt dat zij verantwoordelijk is voor de degradatie van beton die dolomiet als aggregaat bevat. De reactie leidt tot vorming van magnesiumhydroxide (bruciet) en calciumcarbonaat (calciet): Het natriumhydroxide is afkomstig van het cement. Doordat het water absorbeert, is het ontstante bruciet verantwoordelijk voor volumetrische expansie van het beton. Hierdoor kunnen kleine scheurtjes ontstaan, die verdere degradatie van het beton in de hand werken. (nl) |
| dbo:wikiPageExternalLink |
http://www.cement.org/tech/cct_dur_AAR.asp |
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22042208 (xsd:integer) |
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4155 (xsd:nonNegativeInteger) |
| dbo:wikiPageRevisionID |
971995611 (xsd:integer) |
| dbo:wikiPageWikiLink |
dbr:Calcite dbr:Calcium_hydroxide dbr:Calthemite dbr:Pyrite dbr:Sodium_silicate dbr:Alkali dbr:Alkali–aggregate_reaction dbc:Carbonates dbc:Magnesium_compounds dbc:Mechanical_failure_modes dbc:Patterns dbr:Pozzolanic_reaction dbr:Organic_matter dbr:Clay dbr:Concrete dbr:Construction_aggregate dbr:Brucite dbc:Pavements dbr:Dolomite_(rock) dbr:Alkali–silica_reaction dbc:Concrete dbc:Materials_degradation dbc:Building_materials dbr:Cement dbc:Catalysis dbc:Cement dbc:Fracture_mechanics dbc:Silicates dbc:Chemical_reactions dbr:Portlandite dbr:Sodium_carbonate dbr:Sodium_hydroxide dbr:Alkali-silica_reaction |
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dbt:Chem dbt:Short_description dbt:Reaction-stub |
| dcterms:subject |
dbc:Carbonates dbc:Magnesium_compounds dbc:Mechanical_failure_modes dbc:Patterns dbc:Pavements dbc:Concrete dbc:Materials_degradation dbc:Building_materials dbc:Catalysis dbc:Cement dbc:Fracture_mechanics dbc:Silicates dbc:Chemical_reactions |
| gold:hypernym |
dbr:Process |
| rdf:type |
yago:WikicatChemicalReactions yago:ChemicalProcess113446390 yago:ChemicalReaction113447361 yago:NaturalProcess113518963 yago:PhysicalEntity100001930 yago:Process100029677 yago:WikicatInorganicReactions dbo:Election |
| rdfs:comment |
La reazione alcali-carbonato (Alkali-carbonate reaction o ACR) è una reazione alcali-aggregato che determina il deterioramento della durabilità del calcestruzzo a causa della presenza aggregati calcarei dolomitici. (it) De alkali-carbonaat-reactie is een anorganische reactie waarvan verondersteld wordt dat zij verantwoordelijk is voor de degradatie van beton die dolomiet als aggregaat bevat. De reactie leidt tot vorming van magnesiumhydroxide (bruciet) en calciumcarbonaat (calciet): Het natriumhydroxide is afkomstig van het cement. Doordat het water absorbeert, is het ontstante bruciet verantwoordelijk voor volumetrische expansie van het beton. Hierdoor kunnen kleine scheurtjes ontstaan, die verdere degradatie van het beton in de hand werken. (nl) The alkali–carbonate reaction is an alteration process first suspected in the 1950s in Canada for the degradation of concrete containing dolomite aggregates. Alkali from the cement might react with the dolomite crystals present in the aggregate inducing the production of brucite, (MgOH)2, and calcite (CaCO3). This mechanism was tentatively proposed by Swenson and Gillott (1964) and may be written as follows: Brucite (Mg(OH)2), could be responsible for the volumetric expansion after de-dolomitisation of the aggregates, due to absorption of water. (en) |
| rdfs:label |
Alkali–carbonate reaction (en) Reazione alcali carbonato (it) Alkali-carbonaat-reactie (nl) |
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freebase:Alkali–carbonate reaction wikidata:Alkali–carbonate reaction dbpedia-it:Alkali–carbonate reaction dbpedia-nl:Alkali–carbonate reaction http://ta.dbpedia.org/resource/காரம்-கார்பனேட்டு_வினை https://global.dbpedia.org/id/211az |
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dbr:Alkali–aggregate_reaction dbr:Magnesium_hydroxide dbr:Alkali–silica_reaction dbr:Alkali-carbonate_reaction |
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