CA2042883A1 - Method for electrochemical measuring the corrosion rate of reinforcement in concrete structures, sensors and device for application of the method - Google Patents
Method for electrochemical measuring the corrosion rate of reinforcement in concrete structures, sensors and device for application of the methodInfo
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- CA2042883A1 CA2042883A1 CA 2042883 CA2042883A CA2042883A1 CA 2042883 A1 CA2042883 A1 CA 2042883A1 CA 2042883 CA2042883 CA 2042883 CA 2042883 A CA2042883 A CA 2042883A CA 2042883 A1 CA2042883 A1 CA 2042883A1
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- reinforcement
- corrosion rate
- electrode
- signal
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Abstract
SUMMARY OF THE INVENTION
METHOD FOR ELECTROCHEMICAL MEASURING THE CORROSION RATE
OF REINFORCEMENT IN CONCRETE STRUCTURES, SENSORS AND
DEVICE FOR APPLICATION OF THE METHOD.
The method obtains the corrosion rate by using a direct current and taking into account the reinforcement area really affected by an electrical signal.
The signal is applied to the reinforcement through a ring shaped counterelectrode (4), controlled by a main reference electrode (5) housed therein, the following co-operating with the measurements: a) a series of reference electrodes (7, 8, 9); or b) two concentric counterelectro-des (10, 11), or c) two reference electrodes (13, 14), and one concentric ring shaped counterelectrode (12). A True Polarization Resistance value is obtained from the apparent resistance one corrected with the value of the critical -length or the signal attenuation coefficient, or through extrapolation of the values obtained with growing size electrodes, or by confining the electrical signal within a given space.
The described methodology practical realization is pos-sible by means of a corrosion rate meter (6) developed for the envisaged invention.
Figures 1 and 2.
METHOD FOR ELECTROCHEMICAL MEASURING THE CORROSION RATE
OF REINFORCEMENT IN CONCRETE STRUCTURES, SENSORS AND
DEVICE FOR APPLICATION OF THE METHOD.
The method obtains the corrosion rate by using a direct current and taking into account the reinforcement area really affected by an electrical signal.
The signal is applied to the reinforcement through a ring shaped counterelectrode (4), controlled by a main reference electrode (5) housed therein, the following co-operating with the measurements: a) a series of reference electrodes (7, 8, 9); or b) two concentric counterelectro-des (10, 11), or c) two reference electrodes (13, 14), and one concentric ring shaped counterelectrode (12). A True Polarization Resistance value is obtained from the apparent resistance one corrected with the value of the critical -length or the signal attenuation coefficient, or through extrapolation of the values obtained with growing size electrodes, or by confining the electrical signal within a given space.
The described methodology practical realization is pos-sible by means of a corrosion rate meter (6) developed for the envisaged invention.
Figures 1 and 2.
Description
;2(~42883 SCOPE OF T~E INVENTION
The pre~ent invention refers to ~ method ~pecially in-tended for electrochemically mea~uring the corrosion rate o~ reinforcement in concrete ~tructures, by a nondestruc-tive method, with which a high mea6uring accuracy i~ ob-tained.
It is al~o an oh~ect of the inve~tion ~ensor~ for put-ting said method in prsctice, as well as the device witb which the relstive messurements iB practicsll~ carried out.
STATE OF T~E ART
Concrete i8 the most frequently used building msterial for all kind of structures, such as houses, bridge~. roads, dams, irrigation ditches, etc. ~he steel reinforcement em-bedded in these structures is indefinitely frse of corrosion, unleBs the concrete contsins chlorides or it reac~s with the atmosphere carbon dioxide. k~en the met~l reinforcement co-rrodes, the rust building up breaX6 the concrete cover snd this 109s of physical inteErity jeopsrdizes the structura~
security and its load bearing capacity.
The pre~ent invention refers to ~ method ~pecially in-tended for electrochemically mea~uring the corrosion rate o~ reinforcement in concrete ~tructures, by a nondestruc-tive method, with which a high mea6uring accuracy i~ ob-tained.
It is al~o an oh~ect of the inve~tion ~ensor~ for put-ting said method in prsctice, as well as the device witb which the relstive messurements iB practicsll~ carried out.
STATE OF T~E ART
Concrete i8 the most frequently used building msterial for all kind of structures, such as houses, bridge~. roads, dams, irrigation ditches, etc. ~he steel reinforcement em-bedded in these structures is indefinitely frse of corrosion, unleBs the concrete contsins chlorides or it reac~s with the atmosphere carbon dioxide. k~en the met~l reinforcement co-rrodes, the rust building up breaX6 the concrete cover snd this 109s of physical inteErity jeopsrdizes the structura~
security and its load bearing capacity.
2~ Thus, the di~gnosis in situ of the metal structure corro-sion rete implies a high economical interest.
Leaving aside destructive msthod3, that i8 ~ tho~e in which measuremeDts are p~rformed by partially destroyin~ the struc-t~re, which cannot in a lar~e ma~ory of cases even be prec-ticed, nondestru~tive metbods are known, based on appl~ing8 smaI~ampl~tud electrical signal to the reinforcement and measuring the response it provokes. The ratio between the applied potentisl ~nd the response inten~ity is inversall~
proportional to the corro~ion rate, and it i6 known as Pola_ ri~ation Resistance. Its theorical basis wa~ given by Stern and other authors from 1957. For the value to be quentits-tive it is reguired to know the metal are~ on which the Big-nal i~ applied to obtsin ampere/ares unit values.
While the~e methods offer acceptable results at laborsto-ry level, they lack, in practice, of any reliability when 2~ 3 applied to large structures, since for ~tsining thi~, iti9 mandatory to delimite or calculate the metal area on which the me0suring signal spreads, as ebove-mentione~, this being a highly com~licated circumstance when de~ling with real ~cale structures. When applyin~ ~n electrical si~nal, thi~ spreads slong the reinorcement u~til reaching a critical length, which i9 a function Or the ccrro~ioD ra-te itself, of the concrete humidity content~, that is, its re~istivity, of the metal reinforcement surrace and the con crete thickness. It is extromely hard to tske into account all these parameters, due to which ths messurement i8 per_ formed st pre~ent without taking them into account, with the consequent lack of accuracy of the results.
DESCRIPTIO~ OF T~E INVE~TION
~he method proposed by this invention solve~ these pro-blems at entire sstisfsction, and is based on obtaining the corrosion rste by using 9 direct current, slthough taking into aCcount the reinforcement ares reslly affected by the electrical ~ignal.
In order to determine the reinforcement area afrected by the signal, it has been provided thst said signal be emit-ted by the de~ice designed to carry out the method, a~ de_ cribed hereinafter, and be duly recorded, a9 well the stte-nu~tion of ~sid signsl with the distance (criti~l len~th), for which a series of reference slectrodes are u6edO
The ~rue Polarizstion Resistance is obtained from the _ Appsrent Polarization Resistsnce multiplied by a factor which depends on the critical length or the attenuation co~
f~icient of the signal epplied and some co~stants.
An slternative technique to the previous one results from calculating th9 Polarization ReQi~tance as runction Or the measurements obtained with a Qeries de ~rowing area counter-electrode~, by extrapolatin~ properly the results, it being necesssry to resort to a more remote extrapolstion in the case of psssive Qtructures.
2~ 383 There iB al80 the possibility oî the True Polarization Resi3tance being obtained as ~3 function of tbe guotient ~alue between the im~osed sigDal aDd th~ response obtai-ned, referred to the metsl srea delimited between the auxi-lisry reference electrodes Specificslly, in the first csse it ha~ been provided a sen~or compri3in~; a ~mall size ring electrode inside which a reference electrode in in~erted, with sever~l reference electrodes arrsn~;ed st predetermined distances from the center counterelectrode cooperating with s3id counterelec-trode.
In the second case~ the ring counterelectrode, witb its corres~onding reference electrode, i~ surrounded by two ring counterelectrodes havin~ growing si~e~ in regard to the central one.
Finslly, in the third case 9 a rin~ç counterelectrode is used with its corre~pondin~; centrsl electrode, with re~;ard ~to a ring electrode h3ving e considersbly lsr~er diameter, placing two reference electrodes bet~,Jeen the latter aIld the former and, thia w8 y, the surr-ounding eleotrode scts a8 3ignal confining mssns.
In any case, the counterelectrode3 psrticiping in the sensor shall bs metallic or m3de of an~ other electrical conductor material, and they may bs circular or havin~; ~
any other closed geometry ~polygonsl), and they may slso ha~e a monopiec.e structure or be f;rs~mented into different portions towards a better adaptation on the concrete surfa-ce, but being dulsr connected from an electric continuity standpoint Also, in any case, the- sensors may be provided with a -cohtact bed, based on a spon~r and flexible msterisl offe-ring the maximum ~d~ptation capacity ont o th- concrete lrre-gular surface, said contact bed beiDg continuously wet in order to minimize the ohmic drop between the sensor, the reference electrode and the concrete, for which re~son said ~1~4;~3 sen~or~ should havQ incorporated ~ome devices allowing continuous humectation of any ap~ropiate type.
The inventions refèrs also to the device csrrying out such method,said device compri~tin~ a mea~uring ~nd dsts collecting equipment in which a CPU tskes psrt assisted by RAM ~nd ROM memorie~, and~ obviou~ly, by e power source, the CPU recei~ing information from the ~ensor incorporated to the structure to be measurecl, according to sny of the sbove-mentioned embodiments and with the cooperstion of appropiste converters and potentiostatic circui~s, the CPU
being also as6istea by a ~eyboard to enter dsta~ a display for visualizin~ thsm and the typical auxiliary systems, _ ~uch a battery charge control, acoustical indicators, etc.
DESCRIPTION OF T~E DRA~1INGS
To complement the above description and in order to con-tribute to 8 better understanding of the invention chsrac-teristcs, this spec~fication includes a ~et of drawings on which, with an illustr~tive non limitative character, the following has been represented:
Figure 1 shows ~ perspective schematic view of a sensor for carryin~ out the method for eleotrochemicsl measuring the reinforcement corrosion rate iD lar~ size structures, according to the subject matter of the invention;
Figure 2 shows a side elevation ~chemativ view of same sensor in wor~in~ position, thst is, duly adapted to the structure being analyzed, and conDscted to the measuring device itself.
Figures 3 and 4 show, as per similar views to those of Fi~ures 1 and 2, re~pectively, a ~urther sensor type9 name-ly, a sensor which, in lieu of allowing a measure by correc-tion of the apparent polari~ation resistance, ~s in the pre_ vious case, allows using such measurement by employing the growing size counterelectrode method.
Figures 5 and 6 ~how, also following the ~ame line as in ~5 pre~ious ceses, a sensor aimed to obtain the corrosion rate 2~42~383 throu~l sn efficient and ~en~orized confinement of the signal.
Fi~ure 7 shows, lastly, a block diagram correspondin~
to a corrosion metsr which, with the cooperstion of ~ny of the sensors ~hown on sbove figure6, ~llows performin~
the method of this invention.
PREFERRED EM~ODIME~T CF ~E INVE~ON
From these figure~, and more concretely7 Figures 1 thru 6, it msy be seen the way in which the 3ensor (1), of ~n~
type mentioned, incorporates a contact bed t2), based on a spongy and flexible material having capacity to ~dspt it-self to the concrete irregul3r fiurface (3~, a contact bed which should remain continuosly wet in order to minimize the ohmic drop between se~sor, reference electrode snd con_ crete.
Sensors ~1) incorrorate one or more counterelectrodes _ which may be made of metal or any other electric conductor msterisl, as well es one or more reference electrodes Said sensors (1) are structured in any case b~sed on 8 counter-electrode (4) having a rin~ like shape and o~ small ~ize,inside which a refer~nce electrode (5) connected to corrosion mster (6), that is~ the messuring snd data col-lectins de~ice, is housed.
When measuring on the basis of. a correction o~ the sp-parent polarizstion resistance, tbe sensor, accor~ing toFi~ures 1 snd 2, incorporate~, besides the ring counter-electrode (4) and the rererence electrode (5), other re_ ference electrodes (7, 8, 9), which sre installed at pre-viously determined dist~nces dif~erent from that of the central counte~lectroae.
~ owever, when the polarization resi~tance vslue i8 ob-tsined as a function of each counterelectrode area u6ed, ag per Fl~ures 3 ~nd 4, other counter~ectrodes (10, 11), rin~ shaped and concentric in regard to the central COUD-terelectrode (4~, and obviously having growing sizes in 2~42~383 relation to ssme, ag it ma~ ~pecisll~ be noted OD Fig~ 3,are u~ed.
While the True Polsri7ation Resist~nce i8 obtained by mean~ of sn effici~nt and sensorized confinement of the sig-nal, with the central counterelectrode (4) ~nd the referen-ce electrode (5), 8 ring 6hsped and concentric electrode -(12) p~rticipe~ which constitutes the true signsl confining element, and between the rin~ electr~de (5) oth~r reference electrodes (13t 14) are locsted, as it may be ~een on Figu-res 5 ~nd 6.
Tbe mea~urement o~ the Polarizstion Resistance with thesensor shown Otl Figure~ 1 and 2 is c~rried out as Eollows:
- Sensor (1) is convenientl~ located on the concrete sur-~ace (3) to be measured. Next, the various electrodes of sensor are alectrically 3nd pro~erly connected to the meafiu-ring device (6), a9 shown on Figure 2, to which device the concrete reinforcemant (15) is also connected, this reinfor-cement being acceded throu~h a concrete perforatioD.
- Follo~ing this connection, the initial vslue correspon-ding to the reinforcement corrosion potential~ ~s re~d withthe reference electrodes (5), (7), (8) and (9)~ sre recor-ded.
- Next, a potential (or an intensity) is applied from the central counterelectroae (~), which signal should not dis-25 pl~ce the corrosion potential readin~ more than 20-25 m~, and the conjugated v~risble ~ystem response i~ recorded.
Immediately after, a further signal bein~ large enough to produce ~gnificsnt variations on electrocea (7), (8) and -(o), is spplied, recording the difference~ between the pre-viouQ snd subsequent readings to the si~nal application.
_ At thi6 point, with the current ciroulatin~ betweenthe central counterelectrode and the reinforcement (15), snd the potential dif~erence of electrode (5), the apparent polarization resi6tsnce is calculated, snd mathematically operating with this vslue and the potentisl differen~e~ of electrodes (7), (8) and (9), the true polerization resistan-ce vslue and then the corrogion rate is obtained, _ In csse of U9iDg growin~ size electrodes according to the prsctical embodiment f~ ~ensor (1)9 a3 shown on Figu-re~ 3 and 4, it is nece~6sry to apply the electricsl signslas many times as growing ~rea electrodes (10) ~nd (11) are bein~ used, and to messure the re~ponses an equal number of times. ~7ith t~e ~eries of respon~es 80 obtained, an e~tra-polation is made until obtaining 8 counterelectrode area being adeguate to the t~pe of structure being controlled, bearing in mind that the extrapoletion must be farther on when dealing with pa Bsive struGtura 8 .
- When the polarization ra~istance is obtained througb sn efficient and sen~orized confinement of the si~nsl, i.e.
usin~ the sensor (1) of Figures 5 and 6, initial value~ co-rresponding to the corrosion potential of reinforcement and the potential difference~ between the reference electrode~
(13) and (14) sre recorded.
- Next, a current (or potential) i9 applied from the -~0 central couDterelectrode (4) which ~hould not displace thereading of the corro~ion potential more than 20-~0 mV. Im-mediately afterwards, a further signal (intensity or poten-tial, respectively) i8 ap~lied ~om the external or confi-nin~ Gounterelectrode (1~) until the potentiel between the two reference electrodes (1~) and tl4) re~urns to the value previous to the spplication of the ~irst electricsl signal from the central counterelectrode (4)0 _ As soon as the resronge is stabilized, operating msthe-matically with the current flowing between electrode (4) and rein~orcement (15), the aversge ~otential di~ference with electrode (5) and the area delimited by electrode (13) and (14) positions, it is possible to obtain the polarization resistance value and, next, the corrosion rate.
~eferring now to the previously mentioned corrosion meter or meesurin~ device, globally referred to as (6), and repre-2 [)~2883 sented in detail on the block di~gram Or Figure 7, saiddevice, provi~ed with ~ continuos voltage ~ource (16) con-trolled by means o~ a D/A converter, with voltage/current converter~ allowing growlng r~nge6 of oontinuou~ intensity of polarization between ~ 10 uA ~nd ~ 10 mA, th~nks to 8 ~sttery set (18), which i~ rlechargeable ~ ~esn~ of an out side supply (19), incorporates, ~s ~ fund~mental element, a microcontrol~er or CPU ~C), fitted with manu~l snd au_ tomatic control mea~uring execution progrsm~, recorded in ROM memories (21) and with a RAM dsta memory (~) with bst teries. The microcontroller (20) is controlled by a logic program able to select, in every csse, the most adequate measuring technique, ~nd autom~ticslly executing it.-Furthermore, with the CPU (20~, a di~play o visual unit (23) with alph~numeric data in ~CD technology cooperstes,~hick is provided with its rele~nt interfsce with the mi_ crocontroller, ~nd allowin~ to dialogue ~ith the sy~tem and to visuali2e the control and measure psrameters during the processin~ thereof. A keybo~rd (24) ~llowsto enter data and control the device.
A bidirectional inter~ace (25) !ith transmission speed a~d re~ulable dsta collection up to a maximum of 2600 baud, ~llows to bump down data onto an auxiliary computer for their analy~is and processing, or for controllin~ the device itself from said auxiliary computer, in c~se it i~
required to perform a more complex measurement or to have available graphic modes of signal analysis.
Coming back a~ain to ths CPU (20~, this unit controls the D/A converter~ (26) which, in turn, give rise to the controlled voltsge sources (27, 2~), snd to t~e potenti-oststic circuits (29), which are connected through a con-nect~r (30) ~or a galvsnostat and a further connector ~31) for the potentostst.
Complementsry ~y~tems t32) allow controllin~ the batte-ry charge or sny other kind o~ comple~entaru in~ormtion.
, ~V428~33 -- 10 _ From a functional ~tandpoint, the device includes thefollowing lo~ic capacities- Guide and assi6tance to the user throu~h a self-expla nstory menu type pro~ram.
_ ~xecution of measures with 6everal galvanoststic, po-tentio~tatiG end combined tech!niquqs, which messures may be ma~e either in manual or 8uto~,9tiC mode~ the eguipment con-trollin~, in this case, the measurement performin~ parame_ ters, i. e. the type of technigue to be used and the pola-rization level to use, etc.
- Use and control of a non-volstile data memory with sto-rage, display and deletion of the measurement results or pa_ rameter~.
_ Execution of fin~l cslculations of corrosion rate.
- Control of data bumping to a host computer for their further processing.
- Remote operstion of the device connected to a host -computer.
- Execution of 8 logic program performin~ the following sequence:
8 ) Initial measurements of reference potentisls.
b) Selection of the messurement technique or technique~
most ~dequ~te as ~ function of the referenCe potential V3-lues mea~ured at s) and of indicfltor parameters on the type ~nd characteristics of the structure to be measured, intro_ duced in the keybosrd system.
c) Automatic processing of measurements according to tbe techninue or techniques cho~en under b).
d) Analysis of m2asurements ~nd calculation of electric parameters (resistences snd cepacities) flnd of corrosion rate.
It is considered unnecessary to make this description -longer for 0n~ expert in this 6ub~ect to understsnd the sco-pe of the invention and the ~dvantages obtained ~rom it.
Materials, shape, size and arrangement of the 6eversl -;~4~383 _ 11 _ elements may be susceptible of vsri~tion, providing this .
does not mean any modifics-tion in the invention essentisls, The terms dèscribed in this specification should be ta-ksn slways in their most wide snd non-limitative senee.
Leaving aside destructive msthod3, that i8 ~ tho~e in which measuremeDts are p~rformed by partially destroyin~ the struc-t~re, which cannot in a lar~e ma~ory of cases even be prec-ticed, nondestru~tive metbods are known, based on appl~ing8 smaI~ampl~tud electrical signal to the reinforcement and measuring the response it provokes. The ratio between the applied potentisl ~nd the response inten~ity is inversall~
proportional to the corro~ion rate, and it i6 known as Pola_ ri~ation Resistance. Its theorical basis wa~ given by Stern and other authors from 1957. For the value to be quentits-tive it is reguired to know the metal are~ on which the Big-nal i~ applied to obtsin ampere/ares unit values.
While the~e methods offer acceptable results at laborsto-ry level, they lack, in practice, of any reliability when 2~ 3 applied to large structures, since for ~tsining thi~, iti9 mandatory to delimite or calculate the metal area on which the me0suring signal spreads, as ebove-mentione~, this being a highly com~licated circumstance when de~ling with real ~cale structures. When applyin~ ~n electrical si~nal, thi~ spreads slong the reinorcement u~til reaching a critical length, which i9 a function Or the ccrro~ioD ra-te itself, of the concrete humidity content~, that is, its re~istivity, of the metal reinforcement surrace and the con crete thickness. It is extromely hard to tske into account all these parameters, due to which ths messurement i8 per_ formed st pre~ent without taking them into account, with the consequent lack of accuracy of the results.
DESCRIPTIO~ OF T~E INVE~TION
~he method proposed by this invention solve~ these pro-blems at entire sstisfsction, and is based on obtaining the corrosion rste by using 9 direct current, slthough taking into aCcount the reinforcement ares reslly affected by the electrical ~ignal.
In order to determine the reinforcement area afrected by the signal, it has been provided thst said signal be emit-ted by the de~ice designed to carry out the method, a~ de_ cribed hereinafter, and be duly recorded, a9 well the stte-nu~tion of ~sid signsl with the distance (criti~l len~th), for which a series of reference slectrodes are u6edO
The ~rue Polarizstion Resistance is obtained from the _ Appsrent Polarization Resistsnce multiplied by a factor which depends on the critical length or the attenuation co~
f~icient of the signal epplied and some co~stants.
An slternative technique to the previous one results from calculating th9 Polarization ReQi~tance as runction Or the measurements obtained with a Qeries de ~rowing area counter-electrode~, by extrapolatin~ properly the results, it being necesssry to resort to a more remote extrapolstion in the case of psssive Qtructures.
2~ 383 There iB al80 the possibility oî the True Polarization Resi3tance being obtained as ~3 function of tbe guotient ~alue between the im~osed sigDal aDd th~ response obtai-ned, referred to the metsl srea delimited between the auxi-lisry reference electrodes Specificslly, in the first csse it ha~ been provided a sen~or compri3in~; a ~mall size ring electrode inside which a reference electrode in in~erted, with sever~l reference electrodes arrsn~;ed st predetermined distances from the center counterelectrode cooperating with s3id counterelec-trode.
In the second case~ the ring counterelectrode, witb its corres~onding reference electrode, i~ surrounded by two ring counterelectrodes havin~ growing si~e~ in regard to the central one.
Finslly, in the third case 9 a rin~ç counterelectrode is used with its corre~pondin~; centrsl electrode, with re~;ard ~to a ring electrode h3ving e considersbly lsr~er diameter, placing two reference electrodes bet~,Jeen the latter aIld the former and, thia w8 y, the surr-ounding eleotrode scts a8 3ignal confining mssns.
In any case, the counterelectrode3 psrticiping in the sensor shall bs metallic or m3de of an~ other electrical conductor material, and they may bs circular or havin~; ~
any other closed geometry ~polygonsl), and they may slso ha~e a monopiec.e structure or be f;rs~mented into different portions towards a better adaptation on the concrete surfa-ce, but being dulsr connected from an electric continuity standpoint Also, in any case, the- sensors may be provided with a -cohtact bed, based on a spon~r and flexible msterisl offe-ring the maximum ~d~ptation capacity ont o th- concrete lrre-gular surface, said contact bed beiDg continuously wet in order to minimize the ohmic drop between the sensor, the reference electrode and the concrete, for which re~son said ~1~4;~3 sen~or~ should havQ incorporated ~ome devices allowing continuous humectation of any ap~ropiate type.
The inventions refèrs also to the device csrrying out such method,said device compri~tin~ a mea~uring ~nd dsts collecting equipment in which a CPU tskes psrt assisted by RAM ~nd ROM memorie~, and~ obviou~ly, by e power source, the CPU recei~ing information from the ~ensor incorporated to the structure to be measurecl, according to sny of the sbove-mentioned embodiments and with the cooperstion of appropiste converters and potentiostatic circui~s, the CPU
being also as6istea by a ~eyboard to enter dsta~ a display for visualizin~ thsm and the typical auxiliary systems, _ ~uch a battery charge control, acoustical indicators, etc.
DESCRIPTION OF T~E DRA~1INGS
To complement the above description and in order to con-tribute to 8 better understanding of the invention chsrac-teristcs, this spec~fication includes a ~et of drawings on which, with an illustr~tive non limitative character, the following has been represented:
Figure 1 shows ~ perspective schematic view of a sensor for carryin~ out the method for eleotrochemicsl measuring the reinforcement corrosion rate iD lar~ size structures, according to the subject matter of the invention;
Figure 2 shows a side elevation ~chemativ view of same sensor in wor~in~ position, thst is, duly adapted to the structure being analyzed, and conDscted to the measuring device itself.
Figures 3 and 4 show, as per similar views to those of Fi~ures 1 and 2, re~pectively, a ~urther sensor type9 name-ly, a sensor which, in lieu of allowing a measure by correc-tion of the apparent polari~ation resistance, ~s in the pre_ vious case, allows using such measurement by employing the growing size counterelectrode method.
Figures 5 and 6 ~how, also following the ~ame line as in ~5 pre~ious ceses, a sensor aimed to obtain the corrosion rate 2~42~383 throu~l sn efficient and ~en~orized confinement of the signal.
Fi~ure 7 shows, lastly, a block diagram correspondin~
to a corrosion metsr which, with the cooperstion of ~ny of the sensors ~hown on sbove figure6, ~llows performin~
the method of this invention.
PREFERRED EM~ODIME~T CF ~E INVE~ON
From these figure~, and more concretely7 Figures 1 thru 6, it msy be seen the way in which the 3ensor (1), of ~n~
type mentioned, incorporates a contact bed t2), based on a spongy and flexible material having capacity to ~dspt it-self to the concrete irregul3r fiurface (3~, a contact bed which should remain continuosly wet in order to minimize the ohmic drop between se~sor, reference electrode snd con_ crete.
Sensors ~1) incorrorate one or more counterelectrodes _ which may be made of metal or any other electric conductor msterisl, as well es one or more reference electrodes Said sensors (1) are structured in any case b~sed on 8 counter-electrode (4) having a rin~ like shape and o~ small ~ize,inside which a refer~nce electrode (5) connected to corrosion mster (6), that is~ the messuring snd data col-lectins de~ice, is housed.
When measuring on the basis of. a correction o~ the sp-parent polarizstion resistance, tbe sensor, accor~ing toFi~ures 1 snd 2, incorporate~, besides the ring counter-electrode (4) and the rererence electrode (5), other re_ ference electrodes (7, 8, 9), which sre installed at pre-viously determined dist~nces dif~erent from that of the central counte~lectroae.
~ owever, when the polarization resi~tance vslue i8 ob-tsined as a function of each counterelectrode area u6ed, ag per Fl~ures 3 ~nd 4, other counter~ectrodes (10, 11), rin~ shaped and concentric in regard to the central COUD-terelectrode (4~, and obviously having growing sizes in 2~42~383 relation to ssme, ag it ma~ ~pecisll~ be noted OD Fig~ 3,are u~ed.
While the True Polsri7ation Resist~nce i8 obtained by mean~ of sn effici~nt and sensorized confinement of the sig-nal, with the central counterelectrode (4) ~nd the referen-ce electrode (5), 8 ring 6hsped and concentric electrode -(12) p~rticipe~ which constitutes the true signsl confining element, and between the rin~ electr~de (5) oth~r reference electrodes (13t 14) are locsted, as it may be ~een on Figu-res 5 ~nd 6.
Tbe mea~urement o~ the Polarizstion Resistance with thesensor shown Otl Figure~ 1 and 2 is c~rried out as Eollows:
- Sensor (1) is convenientl~ located on the concrete sur-~ace (3) to be measured. Next, the various electrodes of sensor are alectrically 3nd pro~erly connected to the meafiu-ring device (6), a9 shown on Figure 2, to which device the concrete reinforcemant (15) is also connected, this reinfor-cement being acceded throu~h a concrete perforatioD.
- Follo~ing this connection, the initial vslue correspon-ding to the reinforcement corrosion potential~ ~s re~d withthe reference electrodes (5), (7), (8) and (9)~ sre recor-ded.
- Next, a potential (or an intensity) is applied from the central counterelectroae (~), which signal should not dis-25 pl~ce the corrosion potential readin~ more than 20-25 m~, and the conjugated v~risble ~ystem response i~ recorded.
Immediately after, a further signal bein~ large enough to produce ~gnificsnt variations on electrocea (7), (8) and -(o), is spplied, recording the difference~ between the pre-viouQ snd subsequent readings to the si~nal application.
_ At thi6 point, with the current ciroulatin~ betweenthe central counterelectrode and the reinforcement (15), snd the potential dif~erence of electrode (5), the apparent polarization resi6tsnce is calculated, snd mathematically operating with this vslue and the potentisl differen~e~ of electrodes (7), (8) and (9), the true polerization resistan-ce vslue and then the corrogion rate is obtained, _ In csse of U9iDg growin~ size electrodes according to the prsctical embodiment f~ ~ensor (1)9 a3 shown on Figu-re~ 3 and 4, it is nece~6sry to apply the electricsl signslas many times as growing ~rea electrodes (10) ~nd (11) are bein~ used, and to messure the re~ponses an equal number of times. ~7ith t~e ~eries of respon~es 80 obtained, an e~tra-polation is made until obtaining 8 counterelectrode area being adeguate to the t~pe of structure being controlled, bearing in mind that the extrapoletion must be farther on when dealing with pa Bsive struGtura 8 .
- When the polarization ra~istance is obtained througb sn efficient and sen~orized confinement of the si~nsl, i.e.
usin~ the sensor (1) of Figures 5 and 6, initial value~ co-rresponding to the corrosion potential of reinforcement and the potential difference~ between the reference electrode~
(13) and (14) sre recorded.
- Next, a current (or potential) i9 applied from the -~0 central couDterelectrode (4) which ~hould not displace thereading of the corro~ion potential more than 20-~0 mV. Im-mediately afterwards, a further signal (intensity or poten-tial, respectively) i8 ap~lied ~om the external or confi-nin~ Gounterelectrode (1~) until the potentiel between the two reference electrodes (1~) and tl4) re~urns to the value previous to the spplication of the ~irst electricsl signal from the central counterelectrode (4)0 _ As soon as the resronge is stabilized, operating msthe-matically with the current flowing between electrode (4) and rein~orcement (15), the aversge ~otential di~ference with electrode (5) and the area delimited by electrode (13) and (14) positions, it is possible to obtain the polarization resistance value and, next, the corrosion rate.
~eferring now to the previously mentioned corrosion meter or meesurin~ device, globally referred to as (6), and repre-2 [)~2883 sented in detail on the block di~gram Or Figure 7, saiddevice, provi~ed with ~ continuos voltage ~ource (16) con-trolled by means o~ a D/A converter, with voltage/current converter~ allowing growlng r~nge6 of oontinuou~ intensity of polarization between ~ 10 uA ~nd ~ 10 mA, th~nks to 8 ~sttery set (18), which i~ rlechargeable ~ ~esn~ of an out side supply (19), incorporates, ~s ~ fund~mental element, a microcontrol~er or CPU ~C), fitted with manu~l snd au_ tomatic control mea~uring execution progrsm~, recorded in ROM memories (21) and with a RAM dsta memory (~) with bst teries. The microcontroller (20) is controlled by a logic program able to select, in every csse, the most adequate measuring technique, ~nd autom~ticslly executing it.-Furthermore, with the CPU (20~, a di~play o visual unit (23) with alph~numeric data in ~CD technology cooperstes,~hick is provided with its rele~nt interfsce with the mi_ crocontroller, ~nd allowin~ to dialogue ~ith the sy~tem and to visuali2e the control and measure psrameters during the processin~ thereof. A keybo~rd (24) ~llowsto enter data and control the device.
A bidirectional inter~ace (25) !ith transmission speed a~d re~ulable dsta collection up to a maximum of 2600 baud, ~llows to bump down data onto an auxiliary computer for their analy~is and processing, or for controllin~ the device itself from said auxiliary computer, in c~se it i~
required to perform a more complex measurement or to have available graphic modes of signal analysis.
Coming back a~ain to ths CPU (20~, this unit controls the D/A converter~ (26) which, in turn, give rise to the controlled voltsge sources (27, 2~), snd to t~e potenti-oststic circuits (29), which are connected through a con-nect~r (30) ~or a galvsnostat and a further connector ~31) for the potentostst.
Complementsry ~y~tems t32) allow controllin~ the batte-ry charge or sny other kind o~ comple~entaru in~ormtion.
, ~V428~33 -- 10 _ From a functional ~tandpoint, the device includes thefollowing lo~ic capacities- Guide and assi6tance to the user throu~h a self-expla nstory menu type pro~ram.
_ ~xecution of measures with 6everal galvanoststic, po-tentio~tatiG end combined tech!niquqs, which messures may be ma~e either in manual or 8uto~,9tiC mode~ the eguipment con-trollin~, in this case, the measurement performin~ parame_ ters, i. e. the type of technigue to be used and the pola-rization level to use, etc.
- Use and control of a non-volstile data memory with sto-rage, display and deletion of the measurement results or pa_ rameter~.
_ Execution of fin~l cslculations of corrosion rate.
- Control of data bumping to a host computer for their further processing.
- Remote operstion of the device connected to a host -computer.
- Execution of 8 logic program performin~ the following sequence:
8 ) Initial measurements of reference potentisls.
b) Selection of the messurement technique or technique~
most ~dequ~te as ~ function of the referenCe potential V3-lues mea~ured at s) and of indicfltor parameters on the type ~nd characteristics of the structure to be measured, intro_ duced in the keybosrd system.
c) Automatic processing of measurements according to tbe techninue or techniques cho~en under b).
d) Analysis of m2asurements ~nd calculation of electric parameters (resistences snd cepacities) flnd of corrosion rate.
It is considered unnecessary to make this description -longer for 0n~ expert in this 6ub~ect to understsnd the sco-pe of the invention and the ~dvantages obtained ~rom it.
Materials, shape, size and arrangement of the 6eversl -;~4~383 _ 11 _ elements may be susceptible of vsri~tion, providing this .
does not mean any modifics-tion in the invention essentisls, The terms dèscribed in this specification should be ta-ksn slways in their most wide snd non-limitative senee.
Claims (9)
1._ Method for electrochemical measuring the corrosion rate of reinforcement in concrete structures, essentially characterized in obtaining said corrosion rate by using a direct current and taking into account the reinforcement area really effected by an electrical signal.
2._ Method, according to claim 1, characterized in that, in order to determine thereinforcement area affected by the signal, it has been forecast to make a calculation of the apparent polarization resistance through a central counter-electrode and a series of succesive referentes electrodes, so obtaining a True Polarization Resistance from said Appa-rent Polarization Resistance, by multiplying it by a fac-tor depending on the critical length or the attenuation coe-fficient of the applied signal, and with the introduction of the corresponding constants correction.
3._ Method, according to claim 1, characterized in that the polarization resistance value is obtained on the basis of using growing size counterelectrodes, specifically as a function of the ares of each electroded used, extrapolating the results until a counterelectrode area adequate to the structure type being controlled, bearing in mind that said extrapolation should be a remote one for passive structures.
4._ Method, according to claim 1, characterized in that a true polarization resistance is obtained by means of an efficient and sensorized confinement of an electric signal, specifically as a function of the quotient value of the im-posed signal and of the response obtained, referred to the metal area delimited between auxiliary reference electro-des, previously checking the confinement by means of elec-tric, field variation sensors.
5.- Sensor for carrying out the method for electrochemi-cal measuring the corrosion rate of reinforcement in con-crete structures of previous claims, essentially characte-rized in that it is constituted by a series of electrical conductor material electrodes, specifically a ring shaped counterelectrode within which a main reference electrode and a series of electrodes made of an electrical conduc-tor material are housed, all them assembled on a contact bed made of a spongy and flexible material having capaci-ty to adapt itself to the concrete surface irregularities, said contact bed being provided with means which allow to keep it constantly wet in order to minimize the voltage -drop between the electrodes and the concrete.
6.- Sensor, according to claims 2 and 5, characterised is that it incorporates, as auxiliary electrodes, several reference electrodes assembled at different distances from the ring shaped counterelectrode or from the main referen-ce electrode.
7.- Sensor, according to claims 3 and 5, characterized in that it incorporates, as auxiliary electrodes, several ring shaped counterelectrodes having growing diameters -concentric with the main reference electrode.
8.- Sensor, according to claims 4 and 5, characterized in that it incorporates, as auxiliary electrodes, a ring shaped or confining electrode having a larger diameter, and. between this and the main reference electrode, a se-ries of intermediate reference electrodes located at dif-ferent distances from said main reference electrode.
9.- Device for putting into practice said method for electrochemical measuring the corrosion rate of reinfor-cement in concrete structures, as mentioned in claims 1-4, with the sensor of claims 5-8, characterized in that it incorporates a microcontroller or CPU, where the mea-surement control and execution programs are inserted, as well as the calculation, display and storage programs, this CPU controlling D/A converters which, in turn, give rise to direct current voltage sources, as well as poten-tiostatic circuits, having been forecast that said micro-controller shell be assisted also by a keyboard with an auxiliary switch for controlling the polarization level both in voltage and current, a display for acceding to the program menu and data visualizing; a battery charge control; and an interface for coupling it to a host com-puter for analyzing and processin data, the microproce-ssor being also assisted by a power supply source with rechargeable batteries conferring it an adequate autono-my.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ES9001392A ES2024268A6 (en) | 1990-05-18 | 1990-05-18 | Electrochemical measuring method of the rate of corrosion of reinforcing in concrete structures, sensors and apparatus for putting the said method into practice |
| ES9001392 | 1990-05-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2042883A1 true CA2042883A1 (en) | 1991-11-19 |
Family
ID=8267372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2042883 Abandoned CA2042883A1 (en) | 1990-05-18 | 1991-05-17 | Method for electrochemical measuring the corrosion rate of reinforcement in concrete structures, sensors and device for application of the method |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2042883A1 (en) |
| ES (1) | ES2024268A6 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2430939A (en) * | 2005-10-04 | 2007-04-11 | Gareth Kevin Glass | Monitoring method |
| CN108169114A (en) * | 2017-12-29 | 2018-06-15 | 浙江大学 | Reinforcing bar non-uniform corrosion auxiliary electrode limiter self-locking tensioning apparatus |
| CN108254423A (en) * | 2018-04-12 | 2018-07-06 | 国网浙江省电力有限公司电力科学研究院 | Test device and method of the bar built-in fitting in concrete shallow embedding area corrosion rate |
| CN108267491A (en) * | 2018-04-12 | 2018-07-10 | 国网浙江省电力有限公司电力科学研究院 | Test device and method of the angle steel in air-concrete interface corrosion rate |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2317803B1 (en) * | 2008-09-26 | 2010-01-08 | Mediciones Y Corrosion, S.A. | SYSTEM AND METHOD OF EVALUATION OF ANTI-CORROSIVE PROTECTION OF ORGANIC COATINGS. |
| CN115656027B (en) * | 2022-11-01 | 2023-06-13 | 哈尔滨工业大学 | Multifunctional wireless node for electrochemical monitoring of corrosion of steel-concrete structure |
-
1990
- 1990-05-18 ES ES9001392A patent/ES2024268A6/en not_active Expired - Lifetime
-
1991
- 1991-05-17 CA CA 2042883 patent/CA2042883A1/en not_active Abandoned
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2430939A (en) * | 2005-10-04 | 2007-04-11 | Gareth Kevin Glass | Monitoring method |
| CN108169114A (en) * | 2017-12-29 | 2018-06-15 | 浙江大学 | Reinforcing bar non-uniform corrosion auxiliary electrode limiter self-locking tensioning apparatus |
| CN108169114B (en) * | 2017-12-29 | 2023-09-05 | 浙江大学 | Self-locking tensioning device for reinforcing steel bar non-uniform corrosion auxiliary electrode limiter |
| CN108254423A (en) * | 2018-04-12 | 2018-07-06 | 国网浙江省电力有限公司电力科学研究院 | Test device and method of the bar built-in fitting in concrete shallow embedding area corrosion rate |
| CN108267491A (en) * | 2018-04-12 | 2018-07-10 | 国网浙江省电力有限公司电力科学研究院 | Test device and method of the angle steel in air-concrete interface corrosion rate |
| CN108267491B (en) * | 2018-04-12 | 2023-07-07 | 国网浙江省电力有限公司电力科学研究院 | Device and method for testing corrosion rate of angle steel at atmosphere-concrete interface |
| CN108254423B (en) * | 2018-04-12 | 2023-10-17 | 国网浙江省电力有限公司电力科学研究院 | Device and method for testing corrosion rate of reinforced bar embedded part in concrete shallow buried region |
Also Published As
| Publication number | Publication date |
|---|---|
| ES2024268A6 (en) | 1992-02-16 |
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