CN103364313B - A kind of method determining multifactor effect lower prestress concrete chloride ion diffusion mechanism - Google Patents
A kind of method determining multifactor effect lower prestress concrete chloride ion diffusion mechanism Download PDFInfo
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- CN103364313B CN103364313B CN201310284660.2A CN201310284660A CN103364313B CN 103364313 B CN103364313 B CN 103364313B CN 201310284660 A CN201310284660 A CN 201310284660A CN 103364313 B CN103364313 B CN 103364313B
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Abstract
The invention discloses a kind of test unit and the method for determining multifactor effect lower prestress concrete chloride ion diffusion mechanism.Described test unit comprises test block support; Described test block support both sides be respectively provided with one piece with the steel plate of test block support split; Two block plates are connected by four presstressed reinforcing steels being interspersed in steel plate surrounding, and described presstressed reinforcing steel two ends are provided with prestressed anchor.Test unit of the present invention and method, can meet actual needs, its measure multifactor under chloride diffusion coefficient conform to actual.
Description
Technical field
The present invention relates to a kind of test unit and the method for determining multifactor effect lower prestress concrete chloride ion diffusion mechanism.
Background technology
Under current simulation artificial climate environment, multifactor chloride ion corrosion test is all carried out under unstress state, but, in the climatic environment of reality, xoncrete structure, comprising Reinforced Concrete Bridge, concrete building building, underground concrete structure etc. is all when being on active service by when different acting force.Therefore, unstress state Imitating chlorine ion binding capacity tests the diffusion mechanism of chlorion in concrete drawn can not meet actual needs, measure under unstressed test condition simultaneously multifactor under chloride diffusion coefficient do not conform to the actual conditions.
Summary of the invention
The object of the invention is to, for the deficiencies in the prior art, a kind of test unit and the method for determining multifactor effect lower prestress concrete chloride ion diffusion mechanism are provided, under the state of Shi Hanzhang, probe into the diffusion mechanism of chlorion under multifactor environment, study the affecting laws that chloride diffusion coefficient changes with various factors simultaneously.
In order to achieve the above object, technical scheme provided by the invention is:
Describedly determine that the test unit of multifactor effect lower prestress concrete chloride ion diffusion mechanism comprises test block support; Described test block support both sides be respectively provided with one piece with the steel plate of test block support split; Two block plates are connected by four presstressed reinforcing steels being interspersed in steel plate surrounding, and described presstressed reinforcing steel two ends are provided with prestressed anchor.
Wherein, diagonal brace is provided with bottom described steel plate.Described test unit also comprises the metal trough for placing test block support and steel plate.
The test method of the multifactor effect lower prestress of the determination based on above-mentioned test unit concrete chloride ion diffusion mechanism, comprises the steps:
(1) C50-C80 level concrete (i.e. strong concrete, " High Strength Concrete Structures technical regulation " 1.0.2 bar clear stipulaties: high-strength concrete is the C50-C80 level concrete adopting the mineral admixture such as the additives such as cement, sand, stone, high efficiency water reducing agent and flyash ultrafine slag silicon ash to prepare with common process) is adopted to prepare several concrete test blocks;
(2) by placed side by side for concrete test block on test block support, in test block support both sides, test block clamped by steel plate; By four presstressed reinforcing steel one end prestressed anchor anchorings, other end lifting jack carries out the prestress value that first time is stretched to setting simultaneously; After first time stretch-draw, carry out second time stretch-draw when the intermediate plate of prestressed anchor relaxes, use presstressed reinforcing steel ground tackle by one end anchoring of non-for presstressed reinforcing steel anchoring after being stretched to the prestress value of setting, stretch-draw is complete; The prestress value of described setting is 0.7-0.8 times of the ultimate tensile strength (UTS) of presstressed reinforcing steel, is preferably 0.75 times and (carries out stretch-draw according to " tensioning construction technological standards " to steel strand wires (presstressed reinforcing steel).The stress value of setting is 0.75 times of steel strand wires ultimate tensile strength (UTS).Value is 1395Mpa).
(3) by test unit epoxy resin coating, after epoxy cure, the test unit that concrete test block is housed is put into growth cabinet, run growth cabinet, from the salt atomizing nozzle of growth cabinet, spray into NaCl salt fog, concrete test block is corroded, corrode 25-30 days, be preferably 30 days, the flow control of NaCl salt fog is 150 ~ 250L/h; The growth cabinet of described band salt atomizing nozzle is the normal experiment instrument that this area can be commercially available;
(4) concrete test block after corrosion is taken out, carry out chlorine ion content determination and chloride diffusion coefficient mensuration by conventional method.
Compared with prior art, test unit of the present invention utilizes the method for tensioned prestressing bar, relies on steel plate to transmit compressive stress, thus makes concrete test block pressurized.Utilize this test unit, by making a collection of concrete test block, consider the parameter influence such as concrete mix, aggregate thickness, to test block applying lasting compressive stress in various degree, test block is put into artificial environment simulation box, regulate chlorion concentration of saline fog, temperature and humidity, consider that chlorion is from a direction infiltration and both direction penetration mode, carries out the diffusion test of chlorion in prestressed concrete.Adopt test unit of the present invention and method, actual needs can be met, its measure multifactor under chloride diffusion coefficient conform to actual.
Accompanying drawing explanation
Fig. 1 is test unit structural representation of the present invention;
Fig. 2 is the schematic diagram that concrete test block is positioned on test block support;
Fig. 3 is concrete test block schematic diagram;
Fig. 4 is the schematic diagram that test unit is positioned in growth cabinet;
Fig. 5 is concrete test block two dimension corrosion schematic diagram;
Fig. 6 corrodes curve map before and after one dimension corrosion test prestress application;
Fig. 7 corrodes curve map before and after two-dimentional corrosion test prestress application;
Fig. 8 is chloride permeability depth curve figure.
In figure: 1, salt atomizing nozzle; 2, growth cabinet; 3, presstressed reinforcing steel; 4, diagonal brace; 5, concrete test block; 6, steel plate; 7, prestressed anchor; 8, metal trough; 9, test block support.
Embodiment
Embodiment 1
See Fig. 1 to 5, describedly determine that the test unit of multifactor effect lower prestress concrete chloride ion diffusion mechanism comprises test block support 9; Described test block support 9 both sides be respectively provided with one piece with the steel plate 6 of test block support 9 split; Two block plates 6 are connected by four presstressed reinforcing steels 3 being interspersed in steel plate 6 surrounding, and described presstressed reinforcing steel 3 two ends are provided with prestressed anchor 7.Diagonal brace 4 is provided with bottom described steel plate 6.Described test unit also comprises the metal trough 8 for placing test block support 9 and steel plate 6.
Embodiment 2
Based on the test method of the determination multifactor effect lower prestress concrete chloride ion diffusion mechanism of test unit described in embodiment 1, step is as follows:
(1) concrete test block 5 is prepared: temperature, humidity, villaumite concentration, water cement ratio 4 environmental factors are considered in this test.Wherein do orthogonal test with water cement ratio, temperature, humidity three factors, each factor considers three number of levels.Each concrete test block 5 is of a size of standard size 150 × 150 × 150mm, concrete test block has built form removal after 1 day, be placed on temperature for (20 ± 2 DEG C) relative humidity be in the fog room of 90% after maintenance 28d, often organize and take out 6 test blocks altogether as corrosion test block, as shown in Figure 3,3., 6., 2., 5., 1., 4. face, the front, back, left, right, up, down difference label of each concrete test block 5 is; Wherein three 2., 3., 4., 5., 6. five faces smear epoxy resin (epoxy resin in the present embodiment adopts E-44 (610) type epoxy resin and low molecule-650 polyamide to be made into according to the ratio of 1:1), to ensure one end face 1. for the planation surface of chlorion, these three test blocks are corroded as one dimension.Other three 2., 4., 5., 6. face coat epoxy resin, 1., 3. face is as planation surface, and these three test blocks are corroded as two dimension;
Explain: one dimension corrosion refers to coats epoxy resin five of concrete test block 5 faces (2., 3., 4., 5., 6.), only stays a face 1. to carry out chlorine salt corrosion.In like manner, two dimension corrosion coats epoxy resin (2., 4., 5., 6.) four faces, face, and two adjacent surfaces (1., 3.) carries out corroding (see Fig. 5).In the experiment of existing concrete chlorine salt corrosion, the corrosion of general employing one dimension is calculated in order to simplify, but, under the physical environment of reality, exposure xoncrete structure is in an atmosphere multi-direction is often subject to chlorine salt corrosion, and therefore one dimension corrosion can not meet actual requirement of engineering.One dimension corrosion and two dimension corrosion are when identical parameters, and chlorine ion concentration and chloride diffusion coefficient are not identical, and this needs experiment and theoretical checking;
Test block numbering illustrates: C1, C2, C3 represent that water-cement ratio is the test block of 0.4,0.5,0.6 respectively; It is 15 DEG C, 30 DEG C, 45 DEG C that T1, T2, T3 show design temperature; H1, H2, H3 table design relative humidity is 60%, 75%, 90%; C1T1H1 represents water cement ratio 0.4, temperature 15 DEG C, relative humidity 60%, adopts orthogonal experiment (L
9(3
3)), sand coarse aggregate ratio all adopts 30%.Often organize seven test blocks, wherein six are carried out the experiment of a peacekeeping two dimension, and another one makes a strength test.Mix-design and numbering are as table 1:
Table 1 concrete mix (cubic unit water consumption 180kg)
Note: adopt strong concrete, " High Strength Concrete Structures technical regulation " 1.0.2 bar clear stipulaties: high-strength concrete is the C50-C80 level concrete adopting the mineral admixture such as the additives such as cement, sand, stone, high efficiency water reducing agent and flyash ultrafine slag silicon ash to prepare with common process;
(2) by one dimension or two-dimentional test block placed side by side on support 9, note the placement of test block erosional surface position, (1., 3.) distinguished upward and forward.Steel plate 6 with diagonal brace 4 is placed the both sides of test block, shuttled back and forth four presstressed reinforcing steels 3, one end prestressed anchor 7 anchoring of presstressed reinforcing steel 3, and other end stretch-draw jack simultaneous tension 4 presstressed reinforcing steels 3, until design stress value 1395MPa.In first time stretch-draw after complete two hours, when in prestressed anchor 7, intermediate plate relaxes, loss of prestress, at this moment carries out two times tensioning, until design stress value 1395MPa.Finally use prestressed anchor 7 anchoring stretching end, stretch-draw is complete;
(3) by test unit epoxy resin coating, after epoxy cure, the test unit that concrete test block is housed is put into growth cabinet 2, run growth cabinet 2, the NaCl salt fog that concentration of volume percent is 5% is sprayed into from the salt atomizing nozzle 1 of growth cabinet 2, corrode concrete test block 5, corrode 30 days (namely NaCl salt fog spray time is 30 days), the flow control of NaCl salt fog is 200L/h;
(4) chlorine ion content determination: the concrete test block 5 etched in growth cabinet 2 is taken out from test unit, adopt HDM.150 concrete muller, the specification of concrete test block 5 being pressed thickness 5mm is progressively grind into powder to the inside from its surperficial side, to grind into grinding the square hole screen of powder by 0.63mm after 5mm at every turn, to remove coarse particle, then sample is isolated collecting packing, concrete test block 5 is milled to below the former outside surface of distance concrete test block 30mm to be terminated, and namely each core can obtain 6 data.Concrete test block 5 powder (each core obtains 6 parts altogether) collected is placed in baking oven and dries 2h, take out powder, be configured to solution with distilled water and powder, measure chlorine ion concentration with chlorine ion content tester.The results are shown in Figure 6 and Fig. 7, Fig. 6 be with the result comparative analysis carried out of C1T1H1 to one dimension experiment before and after prestress application; Fig. 7 is the comparative analysis carried out with the result of C1T1H1 to two dimension experiment before and after prestress application; Wherein, A represents that one dimension corrodes, and AB represents two dimension corrosion; No matter be that one dimension corrosion or two dimension corrosion chlorine ion concentration are less than concentration before prestress application can find out prestress application from Fig. 6 and Fig. 7 after, illustrate that, under prestressed effect, chloride permeability effect weakens;
(5) chloride diffusion depth measures: by the concrete test block 5 surface watering etched, and move to standard curing room with covered rearing with plastic film.After 14d, with corning machine, concrete test block 5 is processed into standard testing test block (100mm ± 1mm, be highly 50mm ± 2mm), test block will be tested and continue maintenance under standard curing condition until test, first water conservation machine is put in test block during test, the KOH solution injected containing the 0.2mo1/L of 5%NaCl carries out water conservation, test block is taken out at the end of water conservation, cleave in two on pressing machine, test block surface spraying colored indicator (Lucifer Yellow solution) of riving, concrete surface generally turns yellow, and chloride ion-containing part is obviously brighter.The AgNO of the slightly dry rear spray 0.1mol/L in surface
3solution, after 15min, just presents different colours chloride with without chlorine district, can measure the diffusion depth of chlorion along separatrix.
After obtaining diffusion depth by experiment, utilize existing theoretical formula (1) just can calculate chloride diffusion coefficient.Formula derives from " durability design and construction guidbook ":
In formula: D is Chloride Diffusion Coefficient in Concrete, m
2/ s; T is the initial and finishing temperature mean value of anolyte, K; H is test block height, m; x
dfor chloride diffusion depth, m; T is conduction time, s; α is auxiliary variable.
The length of penetration before and after Different Water-Cement Ratio (0.4,0.5,0.6) A, B, C tri-pieces of test block prestress applications is chosen in Fig. 8, can find out, after test block Shi Hanzhang, the chloride permeability degree of depth reduces, and meanwhile, the water cement ratio larger chloride permeability degree of depth is larger.
Claims (2)
1. determine a test method for multifactor effect lower prestress concrete chloride ion diffusion mechanism, it is characterized in that, described method comprises the steps:
(1) based on a kind of test unit determining multifactor effect lower prestress concrete chloride ion diffusion mechanism; Described test unit comprises test block support (9); Described test block support (9) both sides be respectively provided with one piece with the steel plate (6) of test block support (9) split; Two block plates (6) are connected by four presstressed reinforcing steels (3) being interspersed in steel plate (6) surrounding, and described presstressed reinforcing steel (3) two ends are provided with prestressed anchor (7); Described steel plate (6) bottom is provided with diagonal brace (4); Described test unit also comprises the metal trough (8) for placing test block support (9) and steel plate (6);
(2) C50-C80 level concrete is adopted to prepare several concrete test blocks;
(3) by placed side by side for concrete test block on test block support, in test block support both sides, test block clamped by steel plate; By four presstressed reinforcing steel one end prestressed anchor anchorings, other end lifting jack carries out the prestress value that first time is stretched to setting simultaneously; After first time stretch-draw, carry out second time stretch-draw when the intermediate plate of prestressed anchor relaxes, use presstressed reinforcing steel ground tackle by one end anchoring of non-for presstressed reinforcing steel anchoring after being stretched to the prestress value of setting, stretch-draw is complete; The prestress value of described setting is 0.7-0.8 times of the ultimate tensile strength (UTS) of presstressed reinforcing steel;
(4) by test unit epoxy resin coating, after epoxy cure, the test unit that concrete test block is housed is put into growth cabinet, run growth cabinet, regulate chlorion concentration of saline fog, temperature and humidity, consider that chlorion is from a direction infiltration and both direction penetration mode, carry out the diffusion test of chlorion in prestressed concrete, from the salt atomizing nozzle of growth cabinet, spray into NaCl salt fog, concrete test block is corroded, corrode 25-30 days;
(5) concrete test block after corrosion is taken out, carry out chlorine ion content determination and chloride diffusion coefficient mensuration by conventional method.
2. the method for claim 1, is characterized in that, the prestress value of described setting is 0.75 times of the ultimate tensile strength (UTS) of presstressed reinforcing steel.
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| CN104614306B (en) * | 2015-02-04 | 2017-02-22 | 中电建路桥集团有限公司 | Method for testing corrosion effect of gyprock on concrete under action of multiple factors |
| CN107345892B9 (en) * | 2017-05-16 | 2024-02-02 | 浙江工业大学 | Method and device for measuring oxygen diffusion coefficients of cement-based materials in different exposure environments |
| CN109827855B (en) * | 2018-08-30 | 2022-01-07 | 长沙理工大学 | Method for predicting service life of reinforced concrete bridge under seasonal corrosion and fatigue coupling action |
| CN113109159B (en) | 2021-04-02 | 2022-03-08 | 东南大学 | Testing method of medium transmission testing device of concrete under temperature-osmotic pressure-load coupling effect |
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| JP2006329961A (en) * | 2005-05-30 | 2006-12-07 | Taiheiyo Cement Corp | Method for analyzing concentration distribution of element diffused in concrete |
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