CN107064246A - A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage - Google Patents

A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage Download PDF

Info

Publication number
CN107064246A
CN107064246A CN201710383220.0A CN201710383220A CN107064246A CN 107064246 A CN107064246 A CN 107064246A CN 201710383220 A CN201710383220 A CN 201710383220A CN 107064246 A CN107064246 A CN 107064246A
Authority
CN
China
Prior art keywords
reinforcing bar
corr
concrete
fire
damage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201710383220.0A
Other languages
Chinese (zh)
Inventor
杜红秀
陈尧
丁明冬
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Taiyuan University of Technology
Original Assignee
Taiyuan University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Taiyuan University of Technology filed Critical Taiyuan University of Technology
Priority to CN201710383220.0A priority Critical patent/CN107064246A/en
Publication of CN107064246A publication Critical patent/CN107064246A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)

Abstract

The invention discloses a kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage, comprise the following steps：（1）Test material preparation；（2）Simulated fire damage test；（3）Electrochemical Detection, gathered data；（4）Data analysis and lesion assessment.According to the general principle of steel bar corrosion Electrochemical Detection, experimental study has been carried out to Fire simulated furnace reinforcing bar damage according to electrochemistry three elements, the electrochemically determining criterion of Fire simulated furnace reinforcing bar damage is established, diagnostic assessment then has been carried out to actual Fire simulated furnace structure with above-mentioned criterion and assistant analysis model.

Description

A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage
Technical field
The present invention relates to a kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage, belong to concrete NDT technology neck Domain.
Background technology
With Chinese society economy and the fast development of modernization construction, various concrete structures are in a compact mass constantly to be gushed Existing, housing density constantly increases, in addition the extensive use of a large amount of inflammable new materials, and combustion gas, electrical equipment are generally used, and are made The probability for obtaining concrete structure generation fire is greatly increased, and fire damage is growing day by day.Generally, due to cement in concrete Aquation generates substantial amounts of calcium hydroxide, and inside concrete pH value is generally up to 12.5~13.5.In this high alkalinity environment, bag Reinforcing bar in concrete is rolled in because of initial electrochemical action, one layer of very fine and close thickness about 2 × 10 can be quickly generated-8M's Fe3O4And Fe2O3(spinel solid solution) passivating film, it is firmly adsorbed in rebar surface, and reinforcing bar is played a protective role, from And prevent steel bar corrosion.However, when concrete structure is by high temperature sintering (fire), hydrolysis product of cement can occur one and be Row Dehydration, especially Ca (OH)2Meeting dehydration forms CaO at 450 DEG C -500 DEG C, so as to cause concrete neutralisation.When When concrete neutralization depth arrives at rebar surface, the basicity reduction near reinforcing bar, the passivating film of rebar surface is gradually destroyed, steel Corrosion reaction occurs in atmosphere for influential point of tendons.Because said process is an electrochemical process, therefore by detecting steel bar corrosion Concrete neutralisation degree and rebar passivation film state in electrochemical parameter, analysis Fire simulated furnace structure, so that it may estimate coagulation The degree of impairment that protective soil layer and reinforcing bar are subjected to.
The content of the invention
The present invention is intended to provide a kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage, according to steel bar corrosion electrification The general principle of detection is learned, experimental study has been carried out to Fire simulated furnace reinforcing bar damage according to electrochemistry three elements, fire is established The electrochemically determining criterion and assistant analysis model of calamity concrete reinforcement damage, then with above-mentioned criterion and model to actual fire Calamity concrete structure has carried out diagnostic assessment.
The invention provides a kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage, comprise the following steps：
(1) test material preparation：Prepare concrete slab；
(2) simulated fire damage test
1. high-temperature test facility：Hot test uses DRX-36 type concrete hot test stoves, and the equipment uses helical form Electrical heating elements radiant heating in stove as heating source, energy consumption is low, and the rate of heat addition is high, and temperature homogeneity is good.
The power of the hot test stove：36kW；It is 1000 DEG C to allow maximum operating temperature.
2. temperature in fire is set：Due to hydrolysis product of cement Ca (OH)2Kinetics temperature is 450~500 DEG C, and Ca (OH)2Kinetics exactly concrete neutralisation and and then the immediate cause that destroys rebar passivation film, therefore this experiment is by fire Temperature is from 500 DEG C, point 500 DEG C, 600 DEG C, 700 DEG C, 800 DEG C, 900 DEG C of 5 temperature grades；
3. constant temperature time is set：Test specimen is warming up in burner hearth after predetermined temperature, and constant temperature keeps 1h, then cools with stove Cooling.
(3) Electrochemical Detection
1. point layout.Measuring point arrangement can should be noted that and allow reinforcing bar or steel depending on the arrangement according to bar-mat reinforcement during selection measuring point The crossover sites of muscle pass through the center of constant current retaining ring instrument probe, in order to calculate the surface area of the reinforcing bar disturbed by electrochemistry, this Test well shape armored concrete test specimen takes 4 measuring points in the middle part of each side, and cruciform shape armored concrete test specimen is removed in single steel bar Place is taken outside 4 measuring points, and 1 measuring point is taken again in center diagonal reinforcing bar crossover location, and bar list area is single steel bar measuring point 2 times.
2. concrete resistivity RP, steel bar corrosion potential Ecorr, steel bar corrosion current density, JcorrDetection.Concrete is tried After part is sufficiently humidified so as to, its temperature and relative humidity are first detected, then detection resistance rate；As each measuring point RpRespectively less than 15k Ω cm When, then detect EcorrAnd Jcorr。
(4) data analysis
1. reinforcing bar damage situation and the correlation of corrosion potential.Above-mentioned result of the test shows：Reinforcing bar damage situation (concrete Neutralization depth) and EcorrThere is significant correlation.Test specimen without high temperature sintering, its neutralization depth is 0, now corrosion electricity Gesture is in non-corrosion potential area, and its value is 68.4~80.1mV；It is less than through high temperature sintering but neutralization depth or close to protective layer The test specimen of thickness, corrosion potential value is negative to move to -269.13~23.5mV；When concrete is equal to through high temperature sintering to neutralization depth Or more than protective layer thickness, corrosion potential is born shifting and significantly increased to -397.9~-495.6mV.As can be seen here, according to corrosion potential Situation of change, can judge whether the neutralization depth of Fire simulated furnace has met or exceeded protective layer thickness exactly, i.e., Whether reinforcing bar is subject to damage.
2. reinforcing bar damage situation and JcorrCorrelation.Above-mentioned result of the test shows：Reinforcing bar damage situation and JcorrHave brighter Aobvious correlation.Test specimen without high temperature sintering, its neutralization depth is 0, now, JcorrIt is smaller, 0 is essentially close to, through height Warm calcination but neutralization depth are less than or close to the test specimen of protective layer thickness, JcorrIncrease；When concrete is through high temperature sintering When being equal to or more than protective layer thickness to neutralization depth, JcorrSignificantly increase.Relevant information shows, before and after steel bar corrosion JcorrIncrease is substantially and measured value is stable, therefore JcorrCan as Fire simulated furnace reinforcing bar damage auxiliary judgement parameter.
(5) lesion assessment
Relevant information is proposed judges the criterion that steel bar corrosion is destroyed, and ASTM standard (C- according to concrete surface potential 876-87), then the standard that reinforcement corrosion is evaluated with self-potential method is given.Comprehensive data at home and abroad and this experimental study knot Really, the author proposes to evaluate whether rebar passivation film in Fire simulated furnace destroys using steel bar corrosion potential, concrete neutralisation Whether depth is more than the decision criteria of protective layer, is specially：Work as Ecorr>During -200mV, show 500 DEG C of reinforcing bars of reinforcing bar spot temperature Passivating film is not destroyed, i.e., reinforcing bar is undamaged, and concrete neutralization depth does not reach protective layer；Work as Ecorr>During -350mV, show reinforcing bar Spot temperature >=500 DEG C, rebar passivation film is gone to pot, i.e., reinforcing bar is damaged, and concrete neutralization depth meets or exceeds protective layer； As -350mV≤EcorrDuring≤- 200mV, J is utilizedcorrIt is used as the auxiliary judgement criterion of Fire simulated furnace reinforcing bar damage：Work as Jcorr ≥5Jcorr.n(the normal corrosion potential of reinforcing bar, look into reinforcement property specification understand), then reinforcing bar local temperature >=500 DEG C, reinforcing bar is local It is impaired；If Jcorr<5Jcorr.n, then reinforcing bar local temperature<500 DEG C, reinforcing bar is lossless；Wherein：Jcorr.nRefer to the normal corrosion electricity of reinforcing bar Gesture.
In the above method, the operation before Electrochemical Detection includes herein below：
(1) detection prepares
1. concrete surface is handled.Concrete at measuring point should be surface-treated before examinations, remove mortar and The rendering layers such as lime, such as concrete surface have exfoliation layer also to remove.
2. reinforcement location, diameter and thickness of concrete cover are determined.The accuracy of reinforcement location and diameter determines to be counted The accuracy that bar list area is disturbed by electrochemistry is calculated, thus determines detection concrete reinforcement corrosion potential and current density Accuracy can typically determine position and the diameter of concrete reinforcing steel by consulting engineering data, and can not such as find can also apply Magnetic induction instrument is detected.
3. point layout：Well shape armored concrete test specimen takes 4 measuring points in the middle part of each side, the examination of cruciform shape armored concrete Part takes 1 measuring point, and bar list area again in addition to 4 measuring points are taken at single steel bar in center diagonal reinforcing bar crossover location For 2 times of single steel bar measuring point；
4. chisel is repaiied at connection reinforcing bar.In order that measure traverse line connects to carrying out reinforcing bar electrochemistry with the reinforcing bar in concrete Measurement, it is necessary to cut 10cm2Small concrete is to expose reinforcing bar.With the instruments such as file polishing rebar surface, it will be surveyed with crocodile clip The measure traverse line of amount instrument gets up with bar connecting.
5. concrete surface is soaked：Sprayed water, detected again after 30 minutes to concrete surface, be so conducive to obtaining Obtain more accurate Ecorr、JcorrAnd RpValue.
In the above method, the requirement in electrochemical detection is as follows：
1. detecting instrument and technical requirement.Electrochemical apparatus generally use portable constant current retaining ring instrument, and its technology refers to Mark requires EcorrAccuracy of detection is 0.1mV；JcorrAccuracy of detection is 0.001 μ A/cm2；RpAccuracy of detection is 0.1k Ω cm.
2. instrument is connected.The wire of the wire of reinforcing bar and constant current retaining ring instrument is accessed into digital indicator, by constant current retaining ring instrument It is placed in previously selected concrete surface measurement point and measures.
3. control detects environment：0~50 DEG C of concrete temperature；Concrete relative humidity 50%~85%；Concrete resistance Rate Rp<15kΩ·cm。
4. the area of measured reinforcing bar is inputted.Input measurement point is measured the area of reinforcing bar, and measurement point is right-angled intersection steel 2 times of single steel bar area should be inputted during muscle.
5. read and record measurement data.Read and record Ecorr, JcorrAnd RpMeasurement data, measurement data can be stored in survey The data logger in instrument is measured, is then stored in floppy disk.
Checking to above-mentioned Fire simulated furnace reinforcing bar damage：
According to existing assistant analysis model：
(1)EcorrAnalysis model with concrete temperature in fire (t) relation is
Ecorr=-603.6286+1.2716t-0.0013t2, r2=0.96 (1)
(2) concrete neutralization depth (H) and EcorrThe analysis model of absolute value relation is
H=0.1242 | Ecorr|+21.4911, r=0.97 (2)
(3) concrete neutralization depth (H) and the analysis model of concrete temperature in fire (t) relation are
H=0.27699et/0.0334, r2=0.97 (3)
The judge of reinforcing bar temperature in fire：Judged according to above-mentioned Fire simulated furnace reinforcing bar damage electrochemistry criterion, formula (1) Shown Ecorr~t analysis models can carry out auxiliary diagnosis.If known reinforced concrete member surface temperature in fire is (such as by red Outer thermal image detection) and when being about 1h or so by the fiery duration, then using the analysis model, armored concrete structure can be deduced Reinforcing bar electrochemical parameter E in partcorrSize, then by the presumed value with actual measurement EcorrMutually confirmation；On the other hand, when because of certain A little reasons do not survey EcorrDuring value, the presumed value can then replace actual measurement EcorrAnd be used for reinforcing bar temperature in fire, damage situations with And whether concrete neutralization depth reaches the judge of protective layer.
Reinforcing bar damage situation is estimated：Through above-mentioned evaluation, steel is meaned if diagnostic assessment is reinforcing bar temperature in fire >=500 DEG C The mechanical performance of muscle receives damage.After the damage of reinforcing steel bar machinery performance can be by member temperature field analysis, with steel in temperature field The operative temperature that muscle portion position is subjected to substitutes into dependent equation or assessment models to estimate reinforcing steel bar machinery as the temperature in fire of reinforcing bar The degree of impairment of energy.
It can determine that whether concrete neutralization depth reaches guarantor according to above-mentioned Fire simulated furnace reinforcing bar damage electrochemistry criterion Sheath, H~E shown in formula (2)corrShown analysis model can carry out auxiliary diagnosis and calculate concrete neutralization depth value. When because some reasons do not have measured value when Ecorr, H~t analysis models shown in formula (3) can also carry out auxiliary diagnosis, if known steel Reinforced concrete component surface temperature in fire, and when being about 1h or so by the fiery duration, then can be deduced using the model mixed The size of solidifying soil neutralization depth.The presumed value can evaluation result be mutually authenticated, if the presumed value and EcorrEvaluation result is consistent, It is less than or greater than the exact value of thickness of concrete cover, then concrete neutralization depth as being both assessed as neutralization depth It is defined by the numerical value estimated with the model.If the presumed value and EcorrEvaluation result is inconsistent, then needs to detect in conjunction with other Or analysis means such as member temperature field analysis is judged.Concrete neutralization depth value size also can be real using phenolphthalein reagent Survey.
Fire-damaged Steel Bars in Concrete Structure Damage of Passive Film and to induce steel bar corrosion be an electrochemical process, therefore adopt There is reliable theoretical foundation with electrochemical process detection and analysis reinforcing bar damage situation, and it is practical.Fire is established herein to mix Solidifying soil reinforcing bar damage electrochemically determining criterion and assistant analysis model, by detecting the electrochemical parameter of Fire simulated furnace, are utilized Whether this paper decision criterias and assistant analysis model, the temperature that diagnosable and assessment reinforcing bar is subjected to are more than 500 DEG C, and then estimate fire The situation that calamity is damaged to reinforcing steel bar machinery performance, meanwhile, can also diagnose and assess accordingly Fire simulated furnace neutralisation depth whether More than protective layer thickness.
The invention provides a kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage, by detecting steel bar corrosion Electrochemical parameter：Steel bar corrosion potential Ecorr, steel bar corrosion current density, JcorrWith concrete resistivity Rp, mixed to analyze fire Rebar passivation film state in Xtah Crude Clay structure, with this judge concrete cover (i.e. distance of the rebar surface to concrete surface) and The situation for the damage that reinforcing bar is subjected to, to determine whether building can continue to using foundation is provided, advantage is as follows：
(1) Fire simulated furnace reinforcing bar damage electrochemically determining criterion and assistant analysis model, diagnosable and assessment are established Whether the temperature that reinforcing bar is subjected to is more than 500 DEG C, and then estimates the situation that fire is damaged to reinforcing steel bar machinery performance；
(2) criterion whether damaged by the use of steel bar corrosion potential as evaluation reinforcing bar is proposed, and assign it as the auxiliary of evaluation Criterion is helped, the damage status of reinforcing bar can be directly and accurately detected, the efficiency of detection is drastically increased, it is simple and convenient, it is applicable Property it is strong, there is material impact for the evaluation built after calamity；
(3) neutralization depth drawn by the conclusion for drawing this decision method with fresh phenolphthalein reagent is contrasted, The accuracy of this method is determined；
(4) this method is expected in engineering practice as convenient effective Fire simulated furnace reinforcing bar damage checkout and diagnosis method In be widely used.
Embodiment
The present invention is further illustrated below by embodiment, but is not limited to following examples.
Embodiment 1：
(1) test material preparation：Prepare concrete slab
Raw material：The cement of P.O 42.5,5~25mm of rubble, middle sand, diameter 10mm round steel；
Concrete mix：M (cement):M (sand):M (stone):M (water)=385:610:1220:220；(this is four kinds of originals The mass ratio of material)
Test material preparation：30mm × 30mm × 10mm armoured concrete slabs are poured, thickness of concrete cover is 25mm；It is (mixed Solidifying protective soil layer thickness refers to the distance between reinforcing bar and concrete surface) reinforcing bar is placed with well shape and cruciform shape two Kind, and advance extraction wire is for detection；It is standby in natural environment disposed within after test specimen standard curing 28d；
Pour the concrete slab of five identical sizes, reinforcing bar is placed with two kinds of well shape and cruciform shape, and advance Extraction wire is for detection, test specimen standard curing (20 DEG C ± 2 DEG C of thermostat temperature, and relative humidity RH puts more than after 95%) 28d It is standby in Indoor Natural environment.
Sample 1, sample 2, sample 3, sample 4, sample 5 are designated as respectively.
(2) simulated fire damage test
Hot test is carried out using DRX-36 type concrete hot tests stove, temperature in fire is from 500 DEG C, five test blocks 500 DEG C, 600 DEG C, 700 DEG C, 800 DEG C, 900 DEG C of 5 temperature grades are set successively, and test specimen is warming up to predetermined temperature in burner hearth Afterwards, constant temperature is kept for one hour, then with stove cooling down, and cooling finishes taking-up, is placed indoors.
(3) Electrochemical Detection：
1. point layout, this experiment well shape armored concrete test specimen takes 4 measuring points in the middle part of each side, and cruciform shape arrangement of reinforcement is mixed Solidifying soil test specimen takes 1 measuring point again in addition to 4 measuring points are taken at single steel bar in center diagonal reinforcing bar crossover location, and at this On point, bar list area is 2 times of single measuring point.
②Ecorr、JcorrAnd RpValue detection, after concrete sample is sufficiently humidified so as to, first detects its temperature and relative humidity, then Detection resistance rate, as each measuring point RpWhen being generally less than 15k Ω cm, then detect EcorrAnd Jcorr。
Requirement in electrochemical detection is as follows：
1. detecting instrument and technical requirement：Electrochemical apparatus generally use portable constant current retaining ring instrument, and its technology refers to Mark requires EcorrAccuracy of detection is 0.1mV；JcorrAccuracy of detection is 0.001 μ A/cm2；RpAccuracy of detection is 0.1k Ω cm.
2. instrument is connected：The wire of the wire of reinforcing bar and constant current retaining ring instrument is accessed into digital indicator, by constant current retaining ring instrument It is placed in previously selected concrete surface measurement point and measures.
3. environmental Kuznets Curves are detected：0~50 DEG C of concrete temperature；Concrete relative humidity 50%~85%；Concrete resistance Rate Rp<15kΩ·cm。
4. the area of measured reinforcing bar is inputted：Input measurement point is measured the area of reinforcing bar, and measurement point is right-angled intersection steel 2 times of single steel bar area should be inputted during muscle.
5. read and record measurement data：Read and record each sample Ecorr, JcorrAnd RpMeasurement data, measure number According to the data logger that can be stored in measuring instrument, it is then stored in floppy disk, table 1 have recorded each test specimen Electrochemical Detection analysis knot Really.
(4) data analysis：
1. test result indicates that, reinforcing bar damage situation (i.e. concrete neutralization depth) and EcorrThere is significant correlation, Test specimen without high temperature sintering, its neutralization depth is 0, now, EcorrIn non-corrosion potential area, its value is 68.4~ 80.1mV；It is less than through high temperature sintering but neutralization depth or close to the test specimen of protective layer thickness, EcorrValue is negative to move to-269.1-- 323.5mV；When concrete through high temperature sintering to neutralization depth equal to or more than protective layer thickness, EcorrNegative shifting is significantly increased To-397.9-- 495.6mV, it can be seen that, according to EcorrSituation of change, can judge exactly in Fire simulated furnace Whether property depth has met or exceeded whether protective layer thickness, i.e. reinforcing bar are subject to damage.
2. experiment is again showed that, reinforcing bar damage situation and JcorrThere is obvious correlation, the test specimen without high temperature sintering, Its neutralization depth is 0, JcorrSubstantially equal to 0；It is less than by high temperature sintering but neutralization depth or close to protective layer thickness Test specimen, JcorrIncrease；When concrete is equal to or more than protective layer thickness through high temperature sintering to neutralization depth, JcorrHave Significantly increase, therefore JcorrCan as Fire simulated furnace reinforcing bar damage auxiliary judgement parameter.
(5) decision criteria drawn
1. E is utilizedcorrIt is used as the decision criteria of Fire simulated furnace reinforcing bar damage：Work as Ecorr>During -200mV, show reinforcing bar portion Position temperature is less than 500 DEG C, and rebar passivation film is not destroyed, i.e., reinforcing bar is undamaged；As -350mV≤Ecorr, it is necessary to tie during≤- 200mV Close JcorrAnalyzed；Work as Ecorr<During -350mV, show reinforcing bar spot temperature >=500 DEG C, rebar passivation film goes to pot.
2. as -350mV≤EcorrDuring≤- 200mV, J is utilizedcorrIt is accurate as the auxiliary judgement of Fire simulated furnace reinforcing bar damage Then：Work as Jcorr≥5Jcorr.n(the normal corrosion potential of reinforcing bar, look into reinforcement property specification understand), then reinforcing bar local temperature >=500 DEG C, reinforcing bar Local Damaged；If Jcorr<5Jcorr.n, then reinforcing bar local temperature<500 DEG C, reinforcing bar is lossless.
(6) verify：
Neutralization depth is detected：Fresh phenolphthalein reagent is dropped on the concrete cross section newly chiseled, then surveyed according to survey paper It becomes color depth, as neutralization depth, and basis for estimation is：When neutralization depth is less than concrete cover, illustrate reinforcing bar Damage is not affected by, when neutralization depth is more than concrete cover, illustrates that reinforcing bar receives damage.
Because the protective layer thickness of test specimen is 25mm, i.e., when concrete neutralization depth is less than 25mm, reinforcing bar is not affected by Corrosion, when concrete neutralization depth is more than 25mm, reinforcing bar is corroded.From table 1 it follows that test specimen 1, the and of test specimen 2 The E of test specimen 3corrValue is all higher than -200mV, and expression is not affected by corrosion；Meanwhile, neutralization depth is respectively less than 25mm, illustrates reinforcing bar not Corroded, meet the method for concrete damage detection, it was demonstrated that the accuracy of the detection method.As a comparison, the He of test specimen 4 The E of test specimen 5corrWhen value is respectively less than -350mV, concrete neutralization depth is more than 25mm, illustrates that reinforcing bar receives corrosion, meets The method of concrete damage detection, it was demonstrated that the accuracy of the detection method.
Each test specimen Electrochemical Detection analysis result of table 1

Claims (6)

1. a kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage, it is characterised in that comprise the following steps：
(1) test material preparation：Prepare concrete slab；
(2) simulated fire damage test
Using DRX-36 type concrete hot tests stove carry out hot test, temperature in fire from 500 DEG C, successively set 500 DEG C, 600 DEG C, 700 DEG C, 800 DEG C, 900 DEG C of 5 temperature grades；Test specimen is warming up to after predetermined temperature in burner hearth, and constant temperature keeps 1h, so Afterwards with stove cooling down；
(3) Electrochemical Detection
1. concrete resistivity R is detectedP, steel bar corrosion potential Ecorr, steel bar corrosion current density, Jcorr：
After concrete sample is sufficiently humidified so as to, its temperature and relative humidity are first detected, then detection resistance rate；As each measuring point RpIt is small When 15k Ω cm, then detect EcorrAnd Jcorr；Detected using constant current retaining ring instrument；
2. instrument is connected, the wire that the wire of reinforcing bar and constant current ring are protected into instrument accesses digital indicator, then constant current ring shield instrument is pacified It is placed in concrete surface measurement point and measures；
3. control detects environment：Concrete temperature is 0~50 DEG C, and concrete relative humidity is 50% to 85%, concrete resistance Rate is Rp<15kΩ·cm；
4. the area of section of measured reinforcing bar is inputted, when measurement point is right-angled intersection reinforcing bar, the 2 of single steel bar area should be inputted Times；
5. read and record Ecorr、JcorrAnd RpValue, measurement data can be stored in the data logger in measuring instrument, be then stored at In floppy disk；
(4) data analysis and lesion assessment：According to the situation of change of corrosion potential, the neutrality of Fire simulated furnace can be judged exactly Change whether depth has met or exceeded whether protective layer thickness, i.e. reinforcing bar are subject to damage；J before and after steel bar corrosioncorrIncrease is bright Aobvious and measured value is stable, therefore JcorrCan as Fire simulated furnace reinforcing bar damage auxiliary judgement parameter；
1. E is utilizedcorrIt is used as the decision criteria of Fire simulated furnace reinforcing bar damage：Work as Ecorr>During -200mV, show reinforcing bar position temperature Degree is less than 500 DEG C, and rebar passivation film is not destroyed, i.e., reinforcing bar is undamaged, and concrete neutralization depth does not reach protective layer；As -350mV ≤Ecorr, it is necessary to reference to J during≤- 200mVcorrAnalyzed；Work as Ecorr<During -350mV, show reinforcing bar spot temperature >=500 DEG C, Rebar passivation film is gone to pot, i.e., reinforcing bar is damaged, and concrete neutralization depth meets or exceeds protective layer.
2. as -350mV≤EcorrDuring≤- 200mV, J is utilizedcorrIt is used as the auxiliary judgement criterion of Fire simulated furnace reinforcing bar damage：When Jcorr≥5Jcorr.n, then reinforcing bar local temperature >=500 DEG C, reinforcing bar Local Damaged；If Jcorr<5Jcorr.n, then reinforcing bar local temperature< 500 DEG C, reinforcing bar is lossless；Wherein：Jcorr.nRefer to the normal corrosion potential of reinforcing bar.
2. the method for electrochemically determining of Fire simulated furnace reinforcing bar damage according to claim 1, it is characterised in that：Step (2) in, the experimental condition of the hot test is：Power：36kW, permission maximum operating temperature：1000℃.
3. the method for electrochemically determining of Fire simulated furnace reinforcing bar damage according to claim 1, it is characterised in that：Step (3) preliminary preparation carried out before Electrochemical Detection is as follows：
1. concrete surface is handled：Concrete at measuring point should be surface-treated before examinations, remove mortar, pulverized limestone Brush layer, such as concrete surface have exfoliation layer also to remove；
2. reinforcement location, diameter and thickness of concrete cover are determined：The accuracy of reinforcement location and diameter determine to calculate by Electrochemistry disturb bar list area accuracy, thus determine detection concrete reinforcement corrosion potential and current density it is accurate Property can typically determine position and the diameter of concrete reinforcing steel by consulting engineering data, and can not such as find can also apply magnetic strength Instrument is detected；
3. point layout：
Well shape armored concrete test specimen takes 4 measuring points in the middle part of each side, and cruciform shape armored concrete test specimen is removed in single steel bar Place is taken outside 4 measuring points, and 1 measuring point is taken again in center diagonal reinforcing bar crossover location, and bar list area is single steel bar measuring point 2 times；
4. chisel is repaiied at connection reinforcing bar：In order that measure traverse line connects to carrying out reinforcing bar electrochemistry survey with the reinforcing bar in concrete Amount, it is necessary to cut 10cm2Small concrete is to expose reinforcing bar；Polished rebar surface with file, with crocodile clip by the survey of measuring instrument Amount wire gets up with bar connecting；
5. concrete surface is soaked：
Sprayed water, detected again after 30 minutes to concrete surface, be so conducive to obtaining more accurate Ecorr、JcorrWith RpValue.
4. the method for electrochemically determining of Fire simulated furnace reinforcing bar damage according to claim 1, it is characterised in that：Using perseverance Flow retaining ring instrument to be detected, its technical requirement：EcorrAccuracy of detection is 0.1mV；JcorrAccuracy of detection is 0.001 μ A/cm2； RpAccuracy of detection be 0.1k Ω cm.
5. the method for electrochemically determining of Fire simulated furnace reinforcing bar damage according to claim 1, it is characterised in that：Without height The test specimen of warm calcination, its neutralization depth is 0, and now corrosion potential is in non-corrosion potential area, and its value is 68.4~80.1mV； It is less than through high temperature sintering but neutralization depth or close to the test specimen of protective layer thickness, corrosion potential value is negative to move to -269.13~ 23.5mV；When concrete through high temperature sintering to neutralization depth equal to or more than protective layer thickness, negative move of corrosion potential significantly increases Big extremely -397.9~-495.6mV.
6. the method for electrochemically determining of Fire simulated furnace reinforcing bar damage according to claim 1, it is characterised in that：Without height The test specimen of warm calcination, its neutralization depth is 0, now, JcorrIt is smaller, 0 is essentially close to, through high temperature sintering but neutralization depth It is less than or close to the test specimen of protective layer thickness, JcorrIncrease；Be equal to through high temperature sintering to neutralization depth when concrete or During more than protective layer thickness, JcorrSignificantly increase.
CN201710383220.0A 2017-05-26 2017-05-26 A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage Pending CN107064246A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201710383220.0A CN107064246A (en) 2017-05-26 2017-05-26 A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201710383220.0A CN107064246A (en) 2017-05-26 2017-05-26 A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage

Publications (1)

Publication Number Publication Date
CN107064246A true CN107064246A (en) 2017-08-18

Family

ID=59610002

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201710383220.0A Pending CN107064246A (en) 2017-05-26 2017-05-26 A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage

Country Status (1)

Country Link
CN (1) CN107064246A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114113225A (en) * 2021-12-02 2022-03-01 北方民族大学 Post-disaster damage detection method and device for shallow pile foundation of farm shed
CN116128383A (en) * 2023-04-17 2023-05-16 中建五局第三建设有限公司 Anti-corrosion management method for factory building

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101339119A (en) * 2008-08-15 2009-01-07 上海市建筑科学研究院(集团)有限公司 Coastal area concrete reinforcement erosion situation electrochemical test method
KR20120073056A (en) * 2010-12-24 2012-07-04 미승씨엔에스검사주식회사 Device measuring corrosion rate of steel in concrete
CN102706933A (en) * 2012-06-01 2012-10-03 浙江大学 Electrochemical detection method for corrosion degree of steel reinforcing bar in concrete
CN104849326B (en) * 2015-04-16 2017-12-26 同济大学 A kind of concrete reinforcement erosion condition judgement method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101339119A (en) * 2008-08-15 2009-01-07 上海市建筑科学研究院(集团)有限公司 Coastal area concrete reinforcement erosion situation electrochemical test method
KR20120073056A (en) * 2010-12-24 2012-07-04 미승씨엔에스검사주식회사 Device measuring corrosion rate of steel in concrete
CN102706933A (en) * 2012-06-01 2012-10-03 浙江大学 Electrochemical detection method for corrosion degree of steel reinforcing bar in concrete
CN104849326B (en) * 2015-04-16 2017-12-26 同济大学 A kind of concrete reinforcement erosion condition judgement method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
杜红秀 等: "火灾混凝土钢筋损伤的电化学检测与评估", 《建筑材料学报》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114113225A (en) * 2021-12-02 2022-03-01 北方民族大学 Post-disaster damage detection method and device for shallow pile foundation of farm shed
CN116128383A (en) * 2023-04-17 2023-05-16 中建五局第三建设有限公司 Anti-corrosion management method for factory building
CN116128383B (en) * 2023-04-17 2023-07-28 中建五局第三建设有限公司 Anti-corrosion management method for factory building

Similar Documents

Publication Publication Date Title
Raupach et al. Concrete repair to EN 1504: diagnosis, design, principles and practice
Tang et al. Recent durability studies on concrete structure
Yang et al. Development of a new in situ test method to measure the air permeability of high performance concretes
Li et al. Corrosion assessment of reinforced concrete structures exposed to chloride environments in underground tunnels: Theoretical insights and practical data interpretations
Song et al. Probabilistic assessment to predict the time to corrosion of steel in reinforced concrete tunnel box exposed to sea water
Sohail et al. Reinforced concrete degradation in the harsh climates of the Arabian Gulf: field study on 30-to-50-year-old structures
CN107064246A (en) A kind of method for electrochemically determining of Fire simulated furnace reinforcing bar damage
Ryan et al. Comparison of two methods to assess the resistance of concrete to chloride ion penetration
Weydert et al. Electrolytic resistivity of cover concrete: relevance, measurement and interpretation
Schiessl et al. Influence of concrete composition
Ba Ragaa Long-term durability testing of concrete in low and intermediate level waste repositories
Weiss et al. Implementing rapid durability measure for concrete using resistivity and formation factor
Wei Interpretation of hydration process of cement-based materials using resistivity measurement
Liu et al. Corrosion detection of bridge reinforced concrete with induction heating and infrared thermography
Ikotun Effects of concrete quality and cover depth on carbonation-induced reinforcement corrosion and initiation of concrete cover cracking in reinforced concrete structures
Bremner et al. Protection of metals in concrete against corrosion
Liu et al. Bond Deterioration between Corroded Reinforcing Bars with Variable Diameters and Concrete at Elevated Temperatures
Feng et al. Experimental study of competing failure of reinforced concrete based on the weibull distribution
Glinicki et al. Determination of thermal properties of hardening concrete for massive nuclear shielding structures
Khoshroo et al. Minimizing the negative impacts of rebar stored in the Persian Gulf on reinforced concrete corrosion
Mohan et al. Carbonation-induced corrosion on concrete with waste brick powder and hydrated lime additive
Tran Investigation of durability and compressive strength of HPC mixtures and modeling the corrosion initiation time through the electrical resistivity
Busba Effect of localized corrosion of steel on chloride-induced concrete cover cracking in reinforced concrete structures
Cavalline et al. A road map for research and implementation for freeze-thaw resistant highway concrete
Tworzewski et al. Diagnostics of Concrete and Steel in Elements of an Historic Reinforced Concrete Structure. Materials 2021, 14, 306

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication

Application publication date: 20170818

RJ01 Rejection of invention patent application after publication