NO161454B - ELECTROCHEMICAL RE-ALKALIZATION OF CONCRETE. - Google Patents
ELECTROCHEMICAL RE-ALKALIZATION OF CONCRETE. Download PDFInfo
- Publication number
- NO161454B NO161454B NO875438A NO875438A NO161454B NO 161454 B NO161454 B NO 161454B NO 875438 A NO875438 A NO 875438A NO 875438 A NO875438 A NO 875438A NO 161454 B NO161454 B NO 161454B
- Authority
- NO
- Norway
- Prior art keywords
- concrete
- electrode
- carbonated
- accordance
- medium
- Prior art date
Links
- 239000004567 concrete Substances 0.000 title claims description 27
- 238000000034 method Methods 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 8
- 239000004568 cement Substances 0.000 claims description 5
- 239000004570 mortar (masonry) Substances 0.000 claims description 5
- 239000003792 electrolyte Substances 0.000 claims description 4
- 239000006072 paste Substances 0.000 claims description 4
- 230000003014 reinforcing effect Effects 0.000 claims description 4
- -1 sawdust Substances 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- 239000011575 calcium Substances 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 2
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 claims description 2
- 229930006000 Sucrose Natural products 0.000 claims description 2
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 239000004927 clay Substances 0.000 claims description 2
- 239000011888 foil Substances 0.000 claims description 2
- 239000004571 lime Substances 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 239000011490 mineral wool Substances 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 229920003023 plastic Polymers 0.000 claims description 2
- 159000000001 potassium salts Chemical class 0.000 claims description 2
- 230000000979 retarding effect Effects 0.000 claims description 2
- 239000004576 sand Substances 0.000 claims description 2
- 239000002002 slurry Substances 0.000 claims description 2
- 239000005720 sucrose Substances 0.000 claims description 2
- 238000007790 scraping Methods 0.000 claims 1
- 230000002787 reinforcement Effects 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 238000004901 spalling Methods 0.000 description 2
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical class [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000009435 building construction Methods 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011505 plaster Substances 0.000 description 1
- 235000011118 potassium hydroxide Nutrition 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000005488 sandblasting Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000011378 shotcrete Substances 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Description
Den foreliggende oppfinnelsen vedrører en framgangsmåte for re-alkalinisering av karbonatiserte soner i betong e.l. i samsvar med det som er angitt i innledningen til krav 1. The present invention relates to a method for re-alkalinisation of carbonated zones in concrete etc. in accordance with what is stated in the introduction to claim 1.
Armeringsjern og andre stållegemer innstøpt i betong eller andre cement- eller kalkholdige materialer, så som mørtel, puss, sprøytebetong o.l. er normalt beskyttet mot korrosjon p.g.a. det alkaliske miljøet i massen. Imidlertid ødelegges denne alkaliniteten gradvis ved opptak av sure gasser fra atmosfæren, så som karbondioksid, svoveldioksid og svoveltrioksid. Opptaket fører til en gradvis nøytralisering av det alkaliske miljøet. Når pH-verdien av massen er falt til ca. 9,5, er stålet ikke lenger beskyttet, og korrosjon begynner. Rebar and other steel bodies embedded in concrete or other cement or calcareous materials, such as mortar, plaster, shotcrete etc. is normally protected against corrosion due to the alkaline environment in the pulp. However, this alkalinity is gradually destroyed by the absorption of acidic gases from the atmosphere, such as carbon dioxide, sulfur dioxide and sulfur trioxide. The absorption leads to a gradual neutralization of the alkaline environment. When the pH value of the mass has fallen to approx. 9.5, the steel is no longer protected, and corrosion begins.
Den mest kjente nøytraliseringsreaksjonen skyldes opptak av karbondioksid og går under navnet "karbonatiset ing". The most well-known neutralization reaction is due to the absorption of carbon dioxide and goes by the name "carbonatisation".
Karbonat iser ing som fører til bygningsskader i form av korrosjonsangrep på innstøpt stål, som i sin tur resulterer i tap av ståltverrsnitt, utsprengning av betongoverdekning og styrkereduksjon, er allerede i dag et alvorlig problem. Carbonation, which leads to building damage in the form of corrosion attack on embedded steel, which in turn results in loss of steel cross-section, spalling of concrete cover and reduction in strength, is already a serious problem today.
Skader forårsaket av karbonat iset ing har lett for å bli omfattende og er vanskelige og kostbare å reparere. Tradisjo-nelt repareres slike skader ved borthugging av den karbonatiserte sonen, sandblåsing av det derved eksponerte stålet og gjenoppbygning av betongen ved påstøp, påsprøyting eller ved forsegling kombinert med slemming eller sparkling. Resultatet er sjelden fullgodt når det gjelder holdbarhet og bæreevne. Formålet med den foreliggende oppfinnelsen er å fram-bringe en framgangsmåte for reparasjon av karbonatiserte soner i betong o.l. og som gir bedre resultater enn de en oppnår ved å bruke tidligere kjente framgangsmåter. Damage caused by carbonate icing can easily become extensive and is difficult and expensive to repair. Traditionally, such damage is repaired by cutting away the carbonated zone, sandblasting the exposed steel and rebuilding the concrete by casting, spraying or by sealing combined with grouting or spalling. The result is rarely satisfactory in terms of durability and load-bearing capacity. The purpose of the present invention is to produce a method for repairing carbonated zones in concrete etc. and which give better results than those obtained by using previously known procedures.
Det er karakteristisk for karbonat iser ing at skaden som regel begrenser seg til konstruksjonens overflatesone, dvs. i sonen inntil 1. armeringslag. Denne sonen er som regel tynn i forhold til resten av betongtverrsnittet, som er ukarbonati-sert og som hat overskudd av alkaliske stoffer. It is characteristic of carbonation that the damage is usually limited to the construction's surface zone, i.e. in the zone up to the 1st reinforcement layer. This zone is usually thin compared to the rest of the concrete cross-section, which is uncarbonated and has an excess of alkaline substances.
Den foreliggende oppfinnelsen vedrører en framgangsmåte for re-alkalinisering av karbonatiserte soner i samsvar med det som er angitt i den karakteriserende delen av krav 1. The present invention relates to a method for re-alkalinisation of carbonated zones in accordance with what is stated in the characterizing part of claim 1.
Den karbonatiserte sonen tilføres alkaliske stoffer, enten fra betongens e.l. friske indre eller fra et utvendig elektrolytisk medium ved hjelp av en påtrykt elektrisk spenning. De alkaliske stoffene gir den karbonatiserte sonen tilbake sine kor rosjonsbeskyttende egenskaper overfor stål. Alkaline substances are supplied to the carbonated zone, either from the concrete or the like. fresh internal or from an external electrolytic medium by means of an applied electrical voltage. The alkaline substances give the carbonated zone back its corrosion protection properties against steel.
Framgangsmåten bygger på følgende prinsipp: The procedure is based on the following principle:
Når en basisk elektrolyttisk oppløsning med innhold av f.eks. kalsium- , natrium- og kaliumhydroksider utsettes for et elektrisk felt mellom to elektroder, vil det foregå en ionetransport mellom elektrodene og gjøre miljøet rundt den ene elektroden sterkt alkalisk. Denne alkaliniteten beholdes etter at det elektriske feltet opphører. When a basic electrolytic solution containing e.g. calcium, sodium and potassium hydroxides are exposed to an electric field between two electrodes, an ion transport will take place between the electrodes and make the environment around one electrode strongly alkaline. This alkalinity is retained after the electric field ceases.
Framgangsmåten gjennomføres i praksis på følgende måte: 1. Dersom betongen e.l. inneholder to lag med armeringsjern, hvorav det ene ligger i karbonat isert betong og det andre ligger i frisk betong, koples armeringen i karbonati-seringssonen til den ene polen på en likeretter eller et batteri, og det andre laget koples til den andre polen. Ved påsetting av strømmen vandrer alkaliske hydroksyl-ioner til armeringen i den karbonatiserte sonen. Alkaliniteten i den karbonatiserte sonen overvåkes ved hjelp av kjente metoder, f.eks. ved hjelp av pH-ømfint1ige indikatorstoffer eller pH-elektroder. Når ønsket pH-verdi er nådd (vanligvis over 12), kan strømmen slås av . 2. Dersom betongen kun inneholder ett lag med armeringsjern, eller eventuelle andre lag er utilgjengelige, eller avstanden mellom lagene er for stor til at teknikken beskrevet i punkt 1 kan anvendes effektivt, etableres en utvendig elektrode i et egnet elektrolytisk medium på konstruksjonens overflate! Denne elektroden kan bestå av tråder, stenger, plater, folier eller film av metall, ledende plaststoffer eller andre elektrisk ledende stoffer. Elektrolytten kan være vandige oppløsninger av kalsium- , natrium- og/eller kaliumsalter, enten i væske-form eller oppsugd i et porøst medium så som mineralull, cellulosemasse, sagflis, sand, leire og liknende, eller den kan være sterkt retardert betong, mørtel, cementvelling, kalkpasta og liknende. Ved benyttelse av cementbasert basert betong, mørtel eller pasta, tilsettes et sterkt retarderende stoff så som sukrose til dette for å hindre massen i å herde, slik at massen etter endt behandling kan fjernes ved skarping eller spyling. The procedure is carried out in practice in the following way: 1. If the concrete etc. contains two layers of rebar, one of which lies in carbonated concrete and the other in fresh concrete, the reinforcement in the carbonation zone is connected to one pole of a rectifier or battery, and the other layer is connected to the other pole. When the current is applied, alkaline hydroxyl ions migrate to the reinforcement in the carbonated zone. The alkalinity in the carbonated zone is monitored using known methods, e.g. by means of pH-sensitive indicator substances or pH electrodes. When the desired pH value is reached (usually above 12), the current can be switched off. 2. If the concrete contains only one layer of rebar, or any other layers are inaccessible, or the distance between the layers is too large for the technique described in point 1 to be used effectively, an external electrode in a suitable electrolytic medium is established on the construction's surface! This electrode can consist of wires, rods, plates, foils or films of metal, conductive plastics or other electrically conductive substances. The electrolyte can be aqueous solutions of calcium, sodium and/or potassium salts, either in liquid form or absorbed in a porous medium such as mineral wool, cellulose pulp, sawdust, sand, clay and the like, or it can be highly retarded concrete, mortar , cement slurry, lime paste and the like. When using cement-based concrete, mortar or paste, a strong retarding substance such as sucrose is added to this to prevent the mass from hardening, so that the mass can be removed after finishing treatment by sharpening or flushing.
Den utvendige elektroden tilkoples batteriets eller likeretterens ene pol, mens armeringen i den karbonatiserte sonen koples til den andre polen som beskrevet i punkt 1 ovenfor. The external electrode is connected to one pole of the battery or rectifier, while the reinforcement in the carbonated zone is connected to the other pole as described in point 1 above.
Re-alkaliniseringsprosessens hurtighet avhenger av den anvendte likespenningen, som igjen er avhengig av betongens og den eventuelle elektrolyttens ledningsevne, av elektrodetett-heten og av avstanden mellom elektrodene. For vanlig forekom-mende bygningskonstruksjoner ligger den anvendte spenningen, i området 16 - 20 V, hvorved re-alkaliniseringen er utført i løpet av dager eller uker avhengig av de lokale forholdene og av graden og dybden av karbonatiseringen. The speed of the re-alkalinisation process depends on the applied direct voltage, which in turn depends on the conductivity of the concrete and any electrolyte, on the electrode density and on the distance between the electrodes. For commonly occurring building constructions, the applied voltage is in the range 16 - 20 V, whereby the re-alkalization is carried out over days or weeks depending on the local conditions and the degree and depth of the carbonation.
Framgangsmåten er illustrert i den vedlagte tegningen, hvor The procedure is illustrated in the attached drawing, where
fig. 1 viser et snitt gjennom en del av en betongkonstruksjon, hvor spenning påtrykkes over armeringsjern i hhv. frisk og karbonatisert betong, mens fig. 2 viser et tilsvar-ende snitt gjennom en betongkonstruksjon hvor spenning påtrykkes mellom en utvendig elektrode i et elektrolytisk medium og et armeringselement i karbonatisert betong. fig. 1 shows a section through part of a concrete structure, where tension is applied over rebar in or fresh and carbonated concrete, while fig. 2 shows a corresponding section through a concrete structure where voltage is applied between an external electrode in an electrolytic medium and a reinforcing element in carbonated concrete.
Framgangsmåten vil nå bli nærmere beskrevet med henvising til den vedlagte tegningen. I fig. 1 befinner et lag arme-ringsjecn 1 seg i et område med karbonatisert betong, og et lag armeringsjern 2 befinner seg i frisk betong. Armeringen 1 koples til den ene polen på en likeretter eller et batteri 3, og armeringen 2 koples til den andre polen. Ved påsetting av strømmen vandrer alkaliske hydroksylioner til armeringen 1 i den karbonatiserte sonen. The procedure will now be described in more detail with reference to the attached drawing. In fig. 1, a layer of reinforcing iron 1 is in an area of carbonated concrete, and a layer of reinforcing iron 2 is in fresh concrete. The armature 1 is connected to one pole of a rectifier or a battery 3, and the armature 2 is connected to the other pole. When the current is switched on, alkaline hydroxyl ions migrate to the reinforcement 1 in the carbonated zone.
1 fig. 2 befinner en armering 4 seg i en karbonat isert sone i betong. Et egnet elektrolytisk medium 5 er påført på 1 fig. 2, a reinforcement 4 is located in a carbonated zone in concrete. A suitable electrolytic medium 5 is applied to
konstruksjonens overflate. 1 dette mediet S er det etablert en elektrode 6. Elektroden 6 koples til batteriets eller likeretterens 7 ene pol, mens armeringen 4 i den karbonatiserte sonen koples til den andre polen. Ved påsetting av strømmen, vil the structure's surface. In this medium S, an electrode 6 is established. The electrode 6 is connected to one pole of the battery or rectifier 7, while the reinforcement 4 in the carbonated zone is connected to the other pole. When switching on the current, will
alkaliske hydroksylioner vandre fra det utvendige mediet 5 til armeringen 4 i den karbonatiserte sonen. alkaline hydroxyl ions migrate from the external medium 5 to the reinforcement 4 in the carbonated zone.
Som regel velges polariteten slik at armeringen i den karbonatiserte betongen koples til batteriets negative pol. 1 enkelte tilfeller kan det være aktuelt å anvende motsatt polaritet (dette avhenger bl.a. av salt-type i det utvendige elektrolytiske mediet). As a rule, the polarity is chosen so that the reinforcement in the carbonated concrete is connected to the negative pole of the battery. In some cases, it may be appropriate to use the opposite polarity (this depends, among other things, on the type of salt in the external electrolytic medium).
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NO875438A NO161454C (en) | 1986-05-02 | 1987-12-28 | ELECTROCHEMICAL RE-ALKALIZATION OF CONCRETE. |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NO861737A NO160696C (en) | 1986-05-02 | 1986-05-02 | ELECTROCHEMICAL RE-ALKALINIZATION OF CONCRETE. |
PCT/NO1987/000030 WO1987006521A1 (en) | 1986-05-02 | 1987-04-30 | Electrochemical re-alkalization of concrete |
NO875438A NO161454C (en) | 1986-05-02 | 1987-12-28 | ELECTROCHEMICAL RE-ALKALIZATION OF CONCRETE. |
Publications (4)
Publication Number | Publication Date |
---|---|
NO875438L NO875438L (en) | 1987-12-28 |
NO875438D0 NO875438D0 (en) | 1987-12-28 |
NO161454B true NO161454B (en) | 1989-05-08 |
NO161454C NO161454C (en) | 1989-08-16 |
Family
ID=19888899
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
NO861737A NO160696C (en) | 1986-05-02 | 1986-05-02 | ELECTROCHEMICAL RE-ALKALINIZATION OF CONCRETE. |
NO875438A NO161454C (en) | 1986-05-02 | 1987-12-28 | ELECTROCHEMICAL RE-ALKALIZATION OF CONCRETE. |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
NO861737A NO160696C (en) | 1986-05-02 | 1986-05-02 | ELECTROCHEMICAL RE-ALKALINIZATION OF CONCRETE. |
Country Status (4)
Country | Link |
---|---|
AT (1) | ATE79797T1 (en) |
DE (1) | DE3781359T2 (en) |
DK (1) | DK158902C (en) |
NO (2) | NO160696C (en) |
-
1986
- 1986-05-02 NO NO861737A patent/NO160696C/en unknown
-
1987
- 1987-04-30 DE DE19873781359 patent/DE3781359T2/en not_active Revoked
- 1987-04-30 AT AT87902790T patent/ATE79797T1/en not_active IP Right Cessation
- 1987-12-23 DK DK683087A patent/DK158902C/en not_active IP Right Cessation
- 1987-12-28 NO NO875438A patent/NO161454C/en unknown
Also Published As
Publication number | Publication date |
---|---|
DK683087A (en) | 1987-12-23 |
NO875438L (en) | 1987-12-28 |
ATE79797T1 (en) | 1992-09-15 |
DK158902C (en) | 1991-01-07 |
NO160696B (en) | 1989-02-13 |
NO861737L (en) | 1987-11-03 |
NO161454C (en) | 1989-08-16 |
DK683087D0 (en) | 1987-12-23 |
NO160696C (en) | 1989-05-24 |
NO875438D0 (en) | 1987-12-28 |
DE3781359T2 (en) | 1993-03-18 |
DK158902B (en) | 1990-07-30 |
DE3781359D1 (en) | 1992-10-01 |
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