CN107815938B - A kind of comprehensive coverage method of severe cold area concrete extension joint quality control on construction - Google Patents
A kind of comprehensive coverage method of severe cold area concrete extension joint quality control on construction Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000010276 construction Methods 0.000 title claims abstract description 27
- 238000003908 quality control method Methods 0.000 title claims abstract description 9
- 238000011161 development Methods 0.000 claims abstract description 30
- 238000012423 maintenance Methods 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- 238000002360 preparation method Methods 0.000 claims abstract description 14
- 238000013461 design Methods 0.000 claims abstract description 11
- 230000008569 process Effects 0.000 claims abstract description 10
- 239000000463 material Substances 0.000 claims abstract description 8
- 238000004364 calculation method Methods 0.000 claims abstract description 7
- 238000012544 monitoring process Methods 0.000 claims abstract description 6
- 238000009413 insulation Methods 0.000 claims description 38
- 239000002985 plastic film Substances 0.000 claims description 22
- 229920006255 plastic film Polymers 0.000 claims description 22
- 229920006328 Styrofoam Polymers 0.000 claims description 21
- 238000002156 mixing Methods 0.000 claims description 21
- 239000008261 styrofoam Substances 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 239000004576 sand Substances 0.000 claims description 16
- 239000004575 stone Substances 0.000 claims description 16
- 239000004568 cement Substances 0.000 claims description 13
- 239000002689 soil Substances 0.000 claims description 12
- 230000015271 coagulation Effects 0.000 claims description 10
- 238000005345 coagulation Methods 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- 230000004913 activation Effects 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 238000005266 casting Methods 0.000 claims description 5
- 230000000694 effects Effects 0.000 claims description 4
- 229920000742 Cotton Polymers 0.000 claims description 3
- 239000004793 Polystyrene Substances 0.000 claims description 3
- 238000005056 compaction Methods 0.000 claims description 3
- 238000009833 condensation Methods 0.000 claims description 3
- 230000005494 condensation Effects 0.000 claims description 3
- 230000007423 decrease Effects 0.000 claims description 3
- 230000007547 defect Effects 0.000 claims description 3
- 230000000887 hydrating effect Effects 0.000 claims description 3
- 238000013508 migration Methods 0.000 claims description 3
- 230000005012 migration Effects 0.000 claims description 3
- 229920002223 polystyrene Polymers 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 238000006467 substitution reaction Methods 0.000 claims description 3
- 230000001360 synchronised effect Effects 0.000 claims description 3
- 230000002277 temperature effect Effects 0.000 claims description 3
- 229910052738 indium Inorganic materials 0.000 claims 1
- 238000011068 loading method Methods 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 abstract 1
- 238000001723 curing Methods 0.000 description 7
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- 230000033228 biological regulation Effects 0.000 description 2
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- 240000002853 Nelumbo nucifera Species 0.000 description 1
- 235000006508 Nelumbo nucifera Nutrition 0.000 description 1
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- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C11/00—Details of pavings
- E01C11/02—Arrangement or construction of joints; Methods of making joints; Packing for joints
- E01C11/04—Arrangement or construction of joints; Methods of making joints; Packing for joints for cement concrete paving
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C11/00—Details of pavings
- E01C11/24—Methods or arrangements for preventing slipperiness or protecting against influences of the weather
- E01C11/26—Permanently installed heating or blowing devices ; Mounting thereof
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- Engineering & Computer Science (AREA)
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- On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)
- Road Paving Structures (AREA)
Abstract
The invention discloses a kind of comprehensive coverage methods for the severe cold area concrete extension joint quality control on construction for belonging to field of civil engineering.It include: the design of (1) severe cold area concrete extension joint constructing structure；(2) fresh concrete temperature safeguard；(3) concrete heater circuit arrangement；(4) concrete measuring temperature arrangement；(5) concrete heat-insulating maintenance process；(6) heater circuit testing and control project；(7) the concrete strength development course calculation method based on equivalent age.The present invention is structure type, loading condition and military service performance requirement based on concrete extension joint, from multiple angles such as concrete material preparation, heating means and embodiment, maintenance measure, strength development monitoring method, systematically ensures the construction quality of concrete extension joint.By comparing the relationship between equivalent age strength and preparation strength, it can determine that concrete extension joint terminates the time of maintenance or open to traffic；Improve road and bridge construction quality and service life.
Description
Technical field
The invention belongs to field of civil engineering, in particular to a kind of severe cold area concrete extension joint quality control on construction
Comprehensive coverage method.Specifically heating-insulating-strength development comprehensive coverage side of severe cold area concrete extension joint construction
Method.
Background technique
Severe cold area carries out concrete extension joint construction, often faces and enters mould caused by low-temperature material, ground and atmospheric environment
Concrete temperature is low, concrete coagulation process and strength development are slow, or even the problem of freeze-thaw damage occurs.
To cope with the above problem, common counter-measure is to go out machine by heating the mixing water of concrete to promote concrete
Temperature prevents the lost of heat by carrying out insulated curing to the concrete for being poured into mould and by concrete surface
It is heated to accelerate or ensure the hydration process of concrete.But above-mentioned measure be all unable to effective guarantee be cast in expansion joint mix
The development of solidifying soil integral strength, because the roadbed of low temperature can make the temperature of bottom and side concrete lower and hinder intensity
Development.In practical engineering application, often determine to terminate maintenance or open to traffic according to the rebound value of concrete surface；At this point, bottom
The region that portion or lateral stiffness develop slowly will become the weak area of intensity, if its intensity is also not enough to bear extraneous lotus
It carries, then can generate damage during stress, negative shadow is generated to the integrality, impermeabilisation ability and service life at expansion joint
It rings.
Currently, it is directed to the whole guarantee plan of severe cold area concrete extension joint construction quality not yet both at home and abroad, is only
Some of the recommendations measure is proposed in terms of the mix-design of concrete, maintenance process, Insulation and strength development.
U.S.'s ACI306R specification (microthermal climate Under Concrete construction directive/guide), for the concrete construction of severe cold area, it is proposed that
The molding temperature of concrete, a freeze-thaw damage can be resisted needed for curing time, curing means and maturity characterizing method.I
104 regulation of state JGJ/T (architectural engineering winter construction regulation), for the concrete construction under cryogenic conditions, it is proposed that concrete
Power receiving capability, heating curing method, the application method of equivalent age.Though above-mentioned suggestion facilitates severe cold area concrete
The construction at expansion joint, but small in size, large specific surface area this for concrete extension joint, the coagulation being cast in the ground of fluting
Soil structure lacks countermeasure and the technological guidance of system；Wherein the definition of severe cold area refers to the daily temperature change procedure of this area
In have period lower than 4 degrees Celsius.
The present invention is based on the structure type of concrete extension joint, loading condition and military service performance requirements, from concrete material
Preparation, heating means and embodiment, maintenance measure, the multiple angles of strength development monitoring method, systematically ensure concrete
The construction quality at expansion joint proposes heating-insulating-strength development comprehensive coverage side of severe cold area concrete extension joint construction
Method.
Summary of the invention
The purpose of the present invention is to propose to a kind of comprehensive coverage method of severe cold area concrete extension joint quality control on construction,
It is characterized in that, the comprehensive coverage method is the comprehensive guarantor of heating-insulating-strength development of severe cold area concrete extension joint construction
Barrier method；
The comprehensive coverage method includes: 1) severe cold area concrete extension joint constructing structure design；2) fresh concrete
Temperature safeguard；3) concrete heater circuit, temperature sensor arrangement and temperature control scheme；4) concrete heat-insulating maintenance process；
5) the concrete strength development course calculation method based on equivalent age；Specifically it is described below:
1) concrete extension joint constructing structure in severe cold area designs:
Original way of concrete foundations 11 is laid on ground 10, is poured between two sections of original way of concrete foundations 11 by concrete
Concrete extension joint 8；The fixed Telescopic metal seam 6 of the pin 7 sewed among concrete extension joint 8 by Telescopic metal；Heat preservation
Layer 9 is covered on above concrete extension joint 8；The regular arrangement insulation heater strip 1 and appropriate in upper, middle and lower in concrete extension joint 8
Location arrangements temperature sensor 2；Insulation heater strip 1 is connect with temperature controller 4, and temperature sensor 2 and temperature sensor 3 connect
It connects；Temperature sensor 3 and temperature controller 4 are connect with computer 5 respectively；
2) fresh concrete temperature guarantee plan
In severe cold area, the materials and cement, sand, stone for preparing concrete are stored in outdoor, by low temperature environment around
It influences, temperature only has several degrees Celsius or lower than 5 degrees Celsius, even subzero temperature；Meanwhile in the sand and stone of outdoor stacking,
Contained snowy piece and ice cube by rain, snow and the effect of wind；If not taking adequate measures, the concrete prepared only has several
Degree Celsius or be lower than 10 degrees Celsius；The concrete of such low temperature, heat evolution velocity is slow, and it is long to show as setting time, strength development
Slowly；If the concrete of casting in place further distributes heat into ground or environment, so that temperature is lower than minus 7 degrees Celsius,
Then the aquation of concrete can terminate, and can generate freeze-thaw damage；
For the strength development rate for ensureing or accelerating concrete, the mixing water of concrete is heated, to promote coagulation
The out-of-machine temperature of soil；The promotion of fresh concrete temperature, on the one hand ensure concrete after being poured into mould with ground and around ring
Border also has the initial temperature for being greater than 5 degrees Celsius after carrying out heat exchange, on the other hand can also melt sandstone during mix
In snow block and ice cube, prevent residual of these substances in fresh concrete, the later period formed defect；
3) concrete heater circuit, temperature sensor arrangement and temperature control scheme
After being poured into mould, heat therein can scatter and disappear concrete into the ground and air of low temperature, and existing engineering is real
Proof is trampled, the thermo parameters method of concrete is that the high boundary temperature of medium temperature is low, the high temperature of lower of upper temp is low, therefore, such as
The concrete strength synchronized development for making different parts in concrete extension joint, then should heat low-temperature region；Specifically
Way is to delineate grid on the section perpendicular to concrete extension joint length direction, is stretched in the center of each grid along concrete
The length direction of contracting seam lays insulation heater strip, the heated perimeter of every insulation heater stripForPlace gridIt delineatesPrism,
Every heater strip and power supply are in parallel connection, and the temperature control device being all computer controlled individually controls, to realize heating and stop
Only, prism where every insulation heater strip power should enable generates the heating efficiency of 2 degrees Celsius/hour；
Secondly, the arrangement of temperature sensor should be able to reflect the temperature in above-mentioned concrete extension joint in concrete extension joint
；Concrete extension joint sees it is a prism structure on the whole, and after open to traffic, the active position of wheel is apart from coagulation
At 1 meter of native expansion joint edge, therefore, by herein as the monitoring region of concrete temperature field, according to concrete extension joint and
The symmetry for the insulation heater strip wherein arranged, the temperature sensor arranged are divided into middle column and border column, and in each column
Middle arrangement bottom, middle part and three, top sensor, the temperature signal measured by temperature sensor, computer and temperature control
Device is jointly controlled, and the maximum value in temperature signal measured using all temperature sensors is target, to the exhausted of different location
Edge heater strip is switched on or off power supply, realizes the heating to setting position, finally, so that the concrete experience of different parts is identical
Temperature history；The thermal energy that heater circuit is intended to be transformed by externally input electric energy is arranged in concrete, it is mixed to newly mixing
Solidifying soil is heated, to promote the temperature of fresh concrete, to ensure the heat evolution velocity of concrete；
4) concrete heat-insulating maintenance process
Concrete, should be as early as possible in concrete extension joint upper surface after being poured into expansion joint and carrying out vibratory compaction and plastering
It is laid with insulating layer, is sealed, conserves, concrete measure is as follows: (1) covering first layer plastics in the upper surface of concrete extension joint
Film, to prevent the moisture loss of concrete outwardly；(2) styrofoam of 5 cm thicks is covered on first layer plastic film, benefit
Heat scattering and disappearing into air in concrete is prevented with its excellent insulating power；(3) one layer of cotton-wadded quilt is covered in styrofoam,
It is intended to prevent scattering and disappearing for styrofoam seam crossing heat；(4) second layer plastic film is covered, on cotton-wadded quilt to prevent the water in air
Divide migration or condensation into cotton-wadded quilt, prevents the decline of cotton-wadded quilt insulating power；Wherein styrofoam is extruded polystyrene board, fire-protection rating
B1, thermal coefficient are not more than 0.03W/mK；
Dimensionally, the ruler of above-mentioned first layer plastic film from bottom to top, styrofoam, cotton-wadded quilt, second layer plastic film
It is very little to be sequentially increased；The size of the first layer plastic film of lowest part is than being poured into the concrete extension joint of mould in length and width two
Respectively increase by 40 centimetres on a direction, subsequent styrofoam is than first layer plastic film, cotton-wadded quilt than styrofoam, second layer plastic film
It is successively at least more each in length and width both direction than cotton-wadded quilt to increase by 20 centimetres.
(5) the concrete strength development course calculation method based on equivalent age
Equivalent age method based on Arrenius formula can investigate influence of the concrete temperature history experienced to intensity,
The Arrhenius formula k=Ae-(E/RT)What is expressed is the pass between the Rate constant and activation energy. Temperature effect and temperature of chemical reaction
System；In formula, k is chemical reaction rate constant, A is frequency factor constant, e is natural constant, E is activation energy, R is that gas is normal
Number, T are Kelvin；
Institute is to Arrhenius formula k=Ae calculated equivalent age-(E/RT)Integral, by concrete temperature experienced
Degree is converted to 20 degrees Celsius of age, is shown below,
Wherein, teFor equivalent age；TrFor reference temperature 293K (Kelvin), correspond to 20 degrees Celsius；T is concrete
Temperature (Kelvin) experienced in different time points；T is the time for reaching equivalent age.
The strength development course of concrete is expressed with logarithmic function formula S=a+b*ln (t), and wherein t is to reach equivalent age
The time of phase, a and b are constant, the two constants can pass through standard curing condition: temperature=20 degree Celsius, relative humidity >=
The 95% lower concrete sample conserved fits to come in the intensity that 28 day age tested；At this point, t valueFor reach equivalent age when Between；After a and b in formula are fitted, by formulaCalculate the equivalent age substitution logarithm letter of gained
In numerical expression S=a+b*ln (t), then equivalent age strength is acquired；
When terminating maintenance, the intensity of concrete should reach 70% of preparation strength or more；When open to traffic, concrete it is strong
Degree should reach the 100% of preparation strength.By comparing the relationship between equivalent age strength and design strength, concrete can be determined
Expansion joint terminates the time of maintenance or open to traffic.
The mixing water to concrete heats, so that concrete out-of-machine temperature is 20 degrees Celsius；It need to be by mix
The temperature being heated to water is calculated with formula (1):
Wherein, TI, wFor heating after mixing water temperature, degree Celsius；mw、mb、ma、msRespectively mixing water, cement, stone
With the dosage of sand, kilograms per cubic meter；Cw、Cb、Ca、CsThe respectively specific heat capacity of mixing water, cement, stone and sand, kilojoule/(thousand
Gram degree Celsius)；TI, b、TI, a、TI, sThe initial temperature of cement, stone, sand is asked respectively, degree Celsius；TfGo out for concrete after mix
Machine temperature, degree Celsius.
Described to delineate grid on the section perpendicular to concrete extension joint length direction, delineating out grid is 100mm*
The square of 100mm, square center arrangement diameter be 3mm, every meter of length resistance is 33 Ω/m insulation heater strip, mix
The length at solidifying soil expansion joint is 8m, and the specific heat capacity of concrete is 0.97kJ/ (kg DEG C), and the voltage at insulation heater strip both ends is
220V if insulation heater strip is pure resistance element, while not considering concrete hydrating heat release, then the heater strip total power that insulate fever
When, shown in thermal discharge Q hourly such as formula (2), which may make concrete temperature rise value T hourlySSuch as formula (3) institute
Show, meets design requirement (3.5 DEG C/h >, 2 DEG C/h)；Formula (2), the general formula of formula (3) are as follows,
Q is insulation heater strip thermal discharge hourly in formula (2), and kJ/h, U are that thermal discharge may make that concrete is hourly
Temperature rise value TSThe voltage at both ends, V, L are the length of concrete extension joint, and m, R are every meter of resistance of insulation heater strip, Ω/m；
3600 be number of seconds (s) hourly；
T in formula (3)SFor concrete temperature rise value hourly, DEG C/h；Q is adiabatic heat silk thermal discharge hourly, kJ/
h；Q indicates the specific heat capacity of concrete, kJ/ (kg DEG C)；V is the volume of concrete that insulation heater strip need to heat, m3；ρ is coagulation
The bulk density of soil, kg/m3。
The beneficial effects of the invention are as follows structure type, loading condition and military service performance requirement based on concrete extension joint,
From multiple angles, system such as concrete material preparation, heating means and embodiment, maintenance measure, strength development monitoring method
Change the construction quality that ground ensures concrete extension joint.By comparing the relationship between equivalent age strength and preparation strength, can determine
Determine the time that concrete extension joint terminates maintenance or open to traffic；Improve road and bridge construction quality and service life.
Detailed description of the invention
Fig. 1 is severe cold area concrete extension joint construction quality safeguards system schematic diagram.
Fig. 2 is the concrete temperature field schematic diagram of severe cold area concrete extension joint.
Specific embodiment
The present invention proposes a kind of comprehensive coverage method of severe cold area concrete extension joint quality control on construction, specifically
Heating-insulating-strength development Synthesis Support System of severe cold area concrete extension joint construction.It is said with reference to the accompanying drawing
It is bright.
Fig. 1 show severe cold area concrete extension joint construction quality safeguards system schematic diagram.Comprehensive coverage as shown in the figure
System includes: the design of (1) severe cold area concrete extension joint constructing structure；(2) fresh concrete temperature safeguard；(3) it mixes
Solidifying soil heater circuit, temperature sensor arrangement and temperature control scheme；(4) concrete heat-insulating maintenance process；(5) based on equivalent age
Concrete strength development course calculation method；Specifically it is described below:
(1) severe cold area concrete extension joint constructing structure:
Shown in Fig. 1, original way of concrete foundations 11 is laid on ground 10, for by mixing between two sections of original way of concrete foundations 11
The concrete extension joint 8 of solidifying soil casting；The fixed Telescopic metal of the pin 7 sewed among concrete extension joint 8 by Telescopic metal
Seam 6；Insulating layer 9 is covered on above concrete extension joint 8；The regular arrangement insulation heater strip 1 and upper in concrete extension joint 8
In lower appropriate location arrange temperature sensor 2；Insulation heater strip 1 is connect with temperature controller 4, and temperature sensor 2 is adopted with temperature
Collect instrument 3 to connect；Temperature sensor 3 and temperature controller 4 are connect with computer 5 respectively；
(2) fresh concrete temperature guarantee plan
In severe cold area, the materials and cement, sand, stone for preparing concrete are stored in outdoor, by low temperature environment around
It influences, temperature only has several degrees Celsius or lower than 5 degrees Celsius, even subzero temperature；Meanwhile in the sand and stone of outdoor stacking,
Contained snowy piece and ice cube by rain, snow and the effect of wind；If not taking adequate measures, the temperature for the concrete prepared
At 10 degrees Celsius or less；The concrete of such low temperature, heat evolution velocity is slow, shows as that setting time is long, and strength development is slow；Such as
Fruit casting concrete in place further distributes heat into ground or environment, so that temperature is lower than minus 7 degrees Celsius, then concrete
Aquation can terminate, and freeze-thaw damage can be generated；
For the strength development rate for ensureing or accelerating concrete, the mixing water of concrete is heated, to promote coagulation
Native out-of-machine temperature；The promotion of fresh concrete temperature, on the one hand ensure concrete after being poured into mould with ground and ambient enviroment
Also there is the initial temperature for being greater than 5 degrees Celsius after carrying out heat exchange, on the other hand can also melt in sandstone during mix
Snow block and ice cube, prevent residual of these substances in fresh concrete, the later period formed defect.
For these reasons, fresh concrete temperature guarantee plan proposed by the present invention be to the mixing water of concrete into
Row heating, so that concrete out-of-machine temperature is 20 degrees Celsius.The temperature that mixing water is heated to need to be calculated with formula (1):
Wherein, TI, wFor heating after mixing water temperature, degree Celsius；mw、mb、ma、msRespectively mixing water, cement, stone
With the dosage of sand, kilograms per cubic meter；Cw、Cb、Ca、CsThe respectively specific heat capacity of mixing water, cement, stone and sand, kilojoule/(thousand
Gram degree Celsius)；TI, b、TI, a、TI, sThe initial temperature of cement, stone, sand is asked respectively, degree Celsius；TfGo out for concrete after mix
Machine temperature, degree Celsius.
For example, mixing water is heated to 80 degrees Celsius, cement, stone and the sand for the use of initial temperature being 3 degrees Celsius use formula
(1) the concrete initial temperature of preparation is calculated 18 degrees centigrades (related with the dosage of material in concrete).
(3) concrete heater circuit, temperature sensor arrangement and temperature control scheme
After being poured into mould, heat therein can scatter and disappear concrete into the ground and air of low temperature, and existing engineering is real
Proof is trampled, the thermo parameters method of concrete is that the high boundary temperature of medium temperature is low, the high temperature of lower of upper temp is low, is formed as schemed
Temperature field shown in 2；Therefore, the concrete strength synchronized development that such as make different parts in concrete extension joint, then cope with
Low-temperature region is heated；Specific practice is the covering and heat insulating layer 9 on concrete extension joint 8；Flexible perpendicular to concrete
It stitches and delineates grid on the section of 8 length directions, in the center arrangement insulation heater strip 1 of each grid and in upper, middle and lower appropriate location
Arrange temperature sensor 2；Insulation heater strip 1 is connect with temperature controller 4, and temperature sensor 2 is connect with temperature sensor 3；Temperature
Degree Acquisition Instrument 3 and temperature controller 4 are connect with computer 5 respectively.The heated perimeter of every insulation heater strip 1ForPlace gridIt draws IfPrism, each eradication edge heater strip laid in Fig. 1 is all independently controlled, and every heater strip and power supply are in parallel connection
State, the temperature controller 4 all controlled by computer 5 individually control, to realize heating and stop, every insulation heater strip power
Prism where should enabling generates the heating efficiency of 2 degrees Celsius/hour；
Secondly, the arrangement of temperature sensor 2 should be able to reflect that above-mentioned concrete shown in Fig. 2 is stretched in concrete extension joint 8
Temperature field in contracting seam；Concrete extension joint 8 sees it is a prism structure on the whole, after open to traffic, the effect of wheel
Position is at about 1 meter of 8 edge of concrete extension joint, therefore, by herein as the monitoring region of concrete temperature field, according to
Concrete extension joint 8 and symmetry in the insulation heater strip 1 wherein arranged, the temperature sensor 2 arranged divides for middle column
And border column, and bottom, middle part and three, top temperature sensor 2 are arranged in each column, it is measured by temperature sensor
Temperature signal, computer and temperature controller are jointly controlled, in the temperature signal measured with all temperature sensors most
Big value is target, is switched on or off power supply to the insulation heater strip of different location, realizes that the heating to setting position finally makes
The concrete for obtaining different parts undergoes identical temperature history；Arrange that heater circuit is intended to by externally input in concrete
The thermal energy that electric energy is transformed into, heats fresh concrete, to promote the temperature of fresh concrete, to ensure concrete
Heat evolution velocity.
For example, the square that grid is 100mm*100mm is delineated out on the section of concrete extension joint, in square
Center arrangement diameter is 3mm, every meter of length resistance is 33 Ω/m insulation heater strip, and the length of concrete extension joint is 8m, is mixed
The specific heat capacity for coagulating soil is 0.97kJ/ (kg DEG C), and the voltage at insulation heater strip both ends is 220V, if insulation heater strip is pure resistance
Element, while not considering concrete hydrating heat release, then insulate heater strip total power adstante febre, and thermal discharge hourly passes through formula
(2) it is calculated as 660KJ, which may make concrete temperature rise value T hourlySIt is calculated as 3.5 DEG C/h by formula (3), it is full
Sufficient design requirement (3.5 DEG C/h > 2 DEG C/h)；Specific formula (2), formula (3) calculating are as follows,
Formula (2):Formula (3):
(4) concrete heat-insulating maintenance process
Concrete, should the table on concrete extension joint 8 as early as possible after being poured into expansion joint and carrying out vibratory compaction and plastering
Face is laid with insulating layer 9, is sealed, conserves, concrete measure is as follows: 1) in the upper surface of concrete extension joint covering first layer modeling
Film is expected, to prevent the moisture loss of concrete outwardly；2) styrofoam after 5 centimetres is covered on first layer plastic film,
Heat scattering and disappearing into air in concrete is prevented using its excellent insulating power；3) one layer of cotton is covered in styrofoam
Quilt, it is intended to prevent scattering and disappearing for styrofoam seam crossing heat；4) second layer plastic film is covered, on cotton-wadded quilt to prevent in air
Migration or condensation of the moisture into cotton-wadded quilt, prevent the decline of cotton-wadded quilt insulating power.(styrofoam is extruded polystyrene board, fire prevention
Grade B1, thermal coefficient are not more than 0.03W/mK),
Dimensionally, the ruler of above-mentioned first layer plastic film from bottom to top, styrofoam, cotton-wadded quilt, second layer plastic film
It is very little to be sequentially increased；The size of the first layer plastic film of lowest part is than being poured into the concrete extension joint of mould in length and width two
Respectively increase by 40 centimetres on a direction, subsequent styrofoam is than first layer plastic film, cotton-wadded quilt than styrofoam, second layer plastic film
It is successively at least more each in length and width both direction than cotton-wadded quilt to increase by 20 centimetres.
(5) the concrete strength development course calculation method based on equivalent age
Equivalent age method based on Arrenius formula can investigate influence of the concrete temperature history experienced to intensity,
What the Arrhenius formula was expressed is the relationship between the Rate constant and activation energy. Temperature effect and temperature of chemical reaction, such as formula (4) institute
Show:
K=Ae-(E/RT) (4)
In formula, k is chemical reaction rate constant, A is frequency factor constant, e is natural constant, E is activation energy, R is gas
Body constant, T are Kelvin；
Calculated equivalent age be the age that concrete temperature experienced is converted to 20 degrees Celsius, such as formula (5)
It is shown.
Wherein, teFor equivalent age；TrFor reference temperature=293K (Kelvin corresponds to 20 degrees Celsius)；T is coagulation
Soil temperature (Kelvin should be expressed as) experienced in different time points；T is the time for reaching equivalent age.
The strength development course of concrete is expressed with logarithmic function formula S=a+b*ln (t) (6), and wherein t is to reach equivalent
The time of age, a and b be constant, the two constants can by standard curing condition (temperature=20 degree Celsius, relative humidity >=
95%) concrete sample conserved under fits to come in the intensity that 28 day age tested；At this point, t value is to reach equivalent age
Time.After a and b in formula (6) are fitted, formula (5) are calculated into equivalent age substitution formula (6) of gained, then can acquire equivalent age
Phase intensity.
When terminating maintenance, the intensity of concrete should reach 70% of preparation strength or more；When open to traffic, concrete it is strong
Degree should reach the 100% of preparation strength.By comparing the relationship between equivalent age strength and preparation strength, concrete can be determined
Expansion joint terminates the time of maintenance or open to traffic.
In addition, for safety, other strength test methods can be aided with, such as the temperature carried out in rebound method and laboratory
The intensity of concrete in expansion joint is tested with method of curing etc., increases and maintenance or open to traffic decision are terminated to concrete extension joint
Confidence level.
Claims (3)
1. a kind of comprehensive coverage method of severe cold area concrete extension joint quality control on construction, which is characterized in that
The comprehensive coverage method includes: 1) severe cold area concrete extension joint constructing structure design；2) fresh concrete temperature
Safeguard；3) concrete heater circuit, temperature sensor arrangement and temperature control scheme；4) concrete heat-insulating maintenance process；5) base
In the concrete strength development course calculation method of equivalent age；Specifically it is described below:
1) concrete extension joint constructing structure in severe cold area designs:
Original way of concrete foundations (11) is laid on ground (10), for by concrete between two sections of original way of concrete foundations (11)
The concrete extension joint (8) of casting；In the fixed metal of the intermediate pin (7) sewed on by Telescopic metal of concrete extension joint (8)
Expansion joint (6)；Insulating layer (9) is covered on concrete extension joint (8) above；Add in the insulation of concrete extension joint (8) regular arrangement
Heated filament (1) and upper, middle and lower appropriate location arrange temperature sensor (2)；Insulation heater strip (1) is connect with temperature controller (4),
Temperature sensor (2) is connect with temperature sensor (3)；Temperature sensor (3) and temperature controller (4) respectively with computer (5)
Connection；
2) fresh concrete temperature guarantee plan
In severe cold area, the materials and cement, sand, stone for preparing concrete are stored in outdoor, are influenced by low temperature environment around,
Its temperature only has several degrees Celsius or lower than 5 degree Celsius, even subzero temperature；Meanwhile in the sand and stone of outdoor stacking, by rain,
It avenges the effect with wind and contains snowy piece and ice cube；If not taking adequate measures, the concrete prepared only has several Celsius
It spends or lower than 10 degrees Celsius；The concrete of such low temperature, heat evolution velocity is slow, shows as that setting time is long, and strength development is slow；
If casting concrete in place further distributes heat into ground or environment, so that temperature is lower than minus 7 degrees Celsius, then coagulation
The aquation of soil can terminate, and can generate freeze-thaw damage；
For the strength development rate for ensureing or accelerating concrete, the mixing water of concrete is heated, to promote concrete
Out-of-machine temperature；The promotion of fresh concrete temperature, on the one hand ensure concrete after being poured into mould with ground and ambient enviroment into
Also there is the initial temperature greater than 5 degrees Celsius after row heat exchange, on the other hand can also melt in sandstone during mix
Block and ice cube are avenged, residual of these substances in fresh concrete is prevented, forms defect in the later period；
3) concrete heater circuit, temperature sensor arrangement and temperature control scheme
After being poured into mould, heat therein can scatter and disappear concrete into the ground and air of low temperature, existing engineering practice card
Bright, the thermo parameters method of concrete is that the high boundary temperature of medium temperature is low, the high temperature of lower of upper temp is low, therefore, such as to be made
The concrete strength synchronized development for obtaining different parts in concrete extension joint, then should heat low-temperature region；Specific practice
It is to delineate grid on the section perpendicular to concrete extension joint length direction, in the center of each grid along concrete extension joint
Length direction lay insulation heater strip, every insulation heater strip heated perimeter be place grid delineate prism, every
Heater strip and power supply are in parallel connection, and the temperature control device being all computer controlled individually controls, to realize heating and stop, often
Prism where item insulation heater strip power should enable generates the heating efficiency of 2 degrees Celsius/hour；
Secondly, the arrangement of temperature sensor should be able to reflect the temperature field in above-mentioned concrete extension joint in concrete extension joint；
Concrete extension joint sees it is a prism structure on the whole, and after open to traffic, the active position of wheel is apart from concrete
At 1 meter of expansion joint edge, therefore, by herein as the monitoring region of concrete temperature field, according to concrete extension joint and at it
The symmetry of the insulation heater strip of middle arrangement, the temperature sensor arranged are divided into middle column and border column, and in each column
Arrange bottom, middle part and three, top sensor, the temperature signal measured by temperature sensor, computer and temperature controller
Jointly controlled, insulation of the maximum value in temperature signal measured using all temperature sensors as target, to different location
Heater strip is switched on or off power supply, realizes the heating to setting position, finally, so that the concrete experience of different parts is identical
Temperature history；The thermal energy that heater circuit is intended to be transformed by externally input electric energy is arranged in concrete, mixes coagulation to new
Soil is heated, to promote the temperature of fresh concrete, to ensure the heat evolution velocity of concrete；
4) concrete heat-insulating maintenance process
Concrete should be laid in concrete extension joint upper surface as early as possible after being poured into expansion joint and carrying out vibratory compaction and plastering
Insulating layer is sealed, conserves, and concrete measure is as follows: 1) in the upper surface of concrete extension joint cover first layer plastic film,
To prevent the moisture loss of concrete outwardly；2) styrofoam after 5 centimetres is covered on first layer plastic film, it is excellent using its
Different insulating power is lost into air to prevent heat in concrete；3) one layer of cotton-wadded quilt is covered in styrofoam, it is intended to hinder
Only styrofoam seam crossing heat is lost；4) second layer plastic film is covered, on cotton-wadded quilt to prevent the moisture in air to cotton
Migration or condensation by, prevent the decline of cotton-wadded quilt insulating power；Wherein styrofoam is extruded polystyrene board, fire-protection rating B1, is led
Hot coefficient is not more than 0.03W/mK；
Dimensionally, above-mentioned first layer plastic film from bottom to top, styrofoam, cotton-wadded quilt, second layer plastic film size according to
Secondary increase；The size of the first layer plastic film of lowest part is than being poured into the concrete extension joint of mould in two sides of length and width
Each upwards to increase by 40 centimetres, subsequent styrofoam compares cotton than styrofoam, second layer plastic film than first layer plastic film, cotton-wadded quilt
Increase by 20 centimetres by successively at least each in length and width both direction；
5) the concrete strength development course calculation method based on equivalent age
Equivalent age method based on Arrenius formula can investigate influence of the concrete temperature history experienced to intensity, described
Arrhenius formula k=Ae-(E/RT)What is expressed is the relationship between the Rate constant and activation energy. Temperature effect and temperature of chemical reaction；Formula
In, k is chemical reaction rate constant, A is frequency factor constant, e is natural constant, E is activation energy, R is gas constant, T is
Kelvin；
Institute is to Arrhenius formula k=Ae calculated equivalent age-(E/RT)Integral converts concrete temperature experienced
At 20 degrees Celsius of age, it is shown below,
Wherein, teFor equivalent age；TrFor reference temperature=293K, correspond to 20 degrees Celsius；T be concrete in different time points
Temperature experienced；T is the time for reaching equivalent age；
The strength development course of concrete is expressed with logarithmic function formula S=a+b*ln (t), wherein t is to reach equivalent age
Time, a and b are constant, the two constants can pass through standard curing condition: temperature=20 degree Celsius, under relative humidity >=95%
The concrete sample of maintenance fits to come in the intensity that 28 day age tested；At this point, t value is to reach the time of equivalent age；Formula
In a and b fit come after, by formulaCalculate the equivalent age substitution logarithmic function formula S=a+b* of gained
In ln (t), then equivalent age strength is acquired；
When terminating maintenance, the intensity of concrete should reach 70% of preparation strength or more；When open to traffic, the intensity of concrete is answered
Reach the 100% of preparation strength；By comparing the relationship between equivalent age strength and preparation strength, it can determine that concrete is flexible
Seam terminates the time of maintenance or open to traffic.
2. the comprehensive coverage method of severe cold area concrete extension joint quality control on construction according to claim 1, feature
It is, the mixing water to concrete heats, so that concrete out-of-machine temperature is 20 degrees Celsius；Mixing water need to be added
Heat to temperature calculated with formula (1):
Wherein, TI, wFor heating after mixing water temperature, degree Celsius；mw、mb、ma、msRespectively mixing water, cement, stone and sand
Dosage, kilograms per cubic meter；Cw、Cb、Ca、CsThe respectively specific heat capacity of mixing water, cement, stone and sand, kilojoule/(kilogram take the photograph
Family name's degree)；TI, b、TI, a、TI, sThe initial temperature of cement, stone, sand is asked respectively, degree Celsius；TfGo out machine temperature for concrete after mix
Degree, degree Celsius.
3. the comprehensive coverage method of severe cold area concrete extension joint quality control on construction according to claim 1, feature
It is, described to delineate grid on the section perpendicular to concrete extension joint length direction, delineating out grid is 100mm*100mm
Square, square center arrangement insulation heater strip diameter be 3mm, every meter of length resistance is that 33 Ω/m insulation adds
Heated filament, the length of concrete extension joint are 8m, and the specific heat capacity of concrete is 0.97kJ/ (kg DEG C), insulation heater strip both ends
Voltage is 220V, if insulation heater strip is pure resistance element, while not considering concrete hydrating heat release, then the full function of the heater strip that insulate
Rate adstante febre, shown in thermal discharge Q hourly such as formula (2), which may make concrete temperature rise value T hourlySSuch as formula
(3) shown in, meet design requirement (3.5 DEG C/h >, 2 DEG C/h)；Formula (2), the general formula of formula (3) are as follows,
Q is adiabatic heat silk thermal discharge hourly in formula (2), and kJ/h, U are the voltage at insulation heater strip both ends, and V, L are coagulation
The length at native expansion joint, m, R are every meter of resistance of insulation heater strip, Ω/m；3600 be number of seconds (s) hourly；
T in formula (3)SFor concrete temperature rise value hourly, DEG C/h；Q is adiabatic heat silk thermal discharge hourly, kJ/h；Q table
Show the specific heat capacity of concrete, kJ/ (kg DEG C)；V is the volume of concrete that insulation heater strip need to heat, m3；ρ is the appearance of concrete
Weight, kg/m3。
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| CN102797358A (en) * | 2012-08-31 | 2012-11-28 | 中铁二十局集团有限公司 | Construction technique for ultralow-temperature high-property concrete for railway construction in frigid areas |
| CN103787628A (en) * | 2013-12-18 | 2014-05-14 | 中铁五局（集团）有限公司 | Preparation method of low-temperature early strength concrete for high cold permafrost region tunnel |
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| CN102797358A (en) * | 2012-08-31 | 2012-11-28 | 中铁二十局集团有限公司 | Construction technique for ultralow-temperature high-property concrete for railway construction in frigid areas |
| CN103787628A (en) * | 2013-12-18 | 2014-05-14 | 中铁五局（集团）有限公司 | Preparation method of low-temperature early strength concrete for high cold permafrost region tunnel |
| CN105808836A (en) * | 2015-09-17 | 2016-07-27 | 浙江工业大学 | Method for determining temperature process curve of mass concrete with ultrahigh volume of fly ash |
| CN106285006A (en) * | 2016-08-31 | 2017-01-04 | 绍兴职业技术学院 | A kind of cold district concreting in cold-weather method |
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