CN101586993A - Concrete early stage frost heave stress test device and test method - Google Patents

Concrete early stage frost heave stress test device and test method Download PDF

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Publication number
CN101586993A
CN101586993A CNA2009101481987A CN200910148198A CN101586993A CN 101586993 A CN101586993 A CN 101586993A CN A2009101481987 A CNA2009101481987 A CN A2009101481987A CN 200910148198 A CN200910148198 A CN 200910148198A CN 101586993 A CN101586993 A CN 101586993A
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China
Prior art keywords
test
test barrel
concrete
frost heave
barrel
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CNA2009101481987A
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Chinese (zh)
Inventor
赵亚丁
巴恒静
李中华
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哈尔滨工业大学
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Priority to CNA2009101481987A priority Critical patent/CN101586993A/en
Publication of CN101586993A publication Critical patent/CN101586993A/en

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Abstract

A concrete early stage frost heave stress test device comprises a portal frame composed of a support, an upper baffle plate and a lower baffle plate respectively fixed on two ends of the support; a test barrel composed of a cylindrical hollow test barrel body which opens on top and positions on the lower baffle plate, wherein the upper cover of the test barrel covers on the top opening part of the test barrel body; a force sensor disposed between the test barrel and the upper barrel, the end part of which abuts against the upper cover of the test barrel. A concrete early stage frost heave stress test method adopts the concrete early stage frost heave stress test device to measure the frost heave stress of the early stage concrete and the volume change circumstance of the early stage concrete at sub-zero temperature.

Description

Concrete early stage frost heave stress test device and method of testing
Technical field
The present invention relates to a kind of proving installation of concrete early stage frost heave stress, carry out the method for testing of frost heave stress test with adopting this device.
Background technology
Fresh concrete is endured cold and is mostly occurred construction period in the winter time, becomes the main hazard of cold weather concrete operation.The back is from being difficult for finding that it is unusual in appearance though fresh concrete is endured cold, and mechanical property and endurance quality significantly reduce.After fresh concrete is endured cold, because freezing of mixing water causes inside concrete to form big ice crystal, compare with the test specimen that normal temperature hardens down, porosity obviously increases, and especially pore radius rolls up greater than the volume of voids of 0.1 μ m.Therefore on macro property not only compressive strength reduce, and anti-permeability performance, characterize the remarkable deterioration of index of concrete durability with the cohesive force of reinforcing bar etc.
Why can condensing gradually and harden after the concrete mix pouring moulding, until obtaining final strength, is because the result of cement aquation.And the speed of hydrated cementitious mainly is subjected to Temperature Influence except that outside the Pass having with composition material of concrete own and match ratio.When temperature raise, hydration was accelerated, and gain in strength is also very fast; And when temperature is reduced to the freezing point of concrete hole solution, be present in the concrete water some begin to freeze, become solid phase by liquid phase gradually, the water that at this moment participates in cement aquation has reduced, hydration slows down, gain in strength is corresponding slower.After water congeals into ice, volume approximately expanded 9%, and this frost heave stress value is usually greater than the inner early strength value that forms of cement stone, made concrete be subjected to destruction in various degree and caused intensity to reduce and permanance decline.Therefore there is the people to propose to control the quality of negative temperature concrete with frost heave stress and ice content.
Along with China's development of economic construction, China has entered the epoch of an economic liftoff.Economic development for the balance area, central authorities have successively proposed development of the West Regions and Revitalize Old Industrial Bases, accelerate these regional economic construction, improve the living standard of these areas from the people, and its matter of utmost importance is exactly the construction of infrastructure, as the construction of Qinghai-Tibet Railway and the construction of road and bridge in each province and city or the like.But be subject to seasonal restrictions in these area constructions serious, as in the Heilongjiang Province, satisfy time of winter construction the shortest also take 6 months, can have 8-9 month in certain areas; And reaching 11 months less than time of 5 ℃ at some local winter temperature on average of Qinghai-Tibet Platean, this has brought very big difficulty to construction, for accelerating construction progress, will construct under cold conditions inevitably in these places.
When concrete was endured cold in early days, inside concrete produced frost heave stress owing to water freezing expands, and when it surpasses the intensity of xoncrete structure formation, will cause the inside concrete damage.Someone thinks that frost heave stress can be used as a factor of control negative temperature concrete quality.But the method for testing that clear and definite concrete early stage frost heave stress is not also arranged at present both at home and abroad, the proving installation that utilization of the present invention designs voluntarily, the concrete early stage frost heave stress method is explored, in the hope of helpful controlling the concrete later stage performance quality of enduring cold in early days.
Summary of the invention
Technical matters to be solved by this invention is, a kind of concrete early stage frost heave stress test device and method of testing are provided, and in order to the early stage frost heave stress of measurement concrete, and measures early concrete in subzero temperature situation lower volume situation of change.
A kind of concrete early stage frost heave stress test device comprises portal frame, and this portal frame mainly is made up of support and the overhead gage and the lower baffle plate that are separately fixed at these support two ends; Test barrel comprises the test barrel body of a cylindrical hollow, and test barrel body top opening, test barrel loam cake are covered on this test barrel body top opening part, and this test barrel places on this lower baffle plate; Force transducer places between this test barrel and this overhead gage, and the end of this force transducer pushes against this test barrel loam cake.
This force transducer inside has a semiconductor strain gauge, links to each other with the end of this force transducer.
This proving installation also comprises a signal amplifier, and an end is electrically connected this semiconductor strain gauge, and the other end is electrically connected a Displaying Meter.
This test barrel body also has lower opening, and the test barrel lower cover is covered on this lower opening place.
A kind of stage frost heave stress test method comprises the steps: step 1, the concrete for preparing is packed in the test barrel, is 20 ℃ in temperature, and relative humidity is precuring 6 hours in 90% the environment; Step 2, will fill concrete test barrel and add the test barrel upper and lower covers, and put into the portal frame that places refrigerator in advance, and this force transducer is placed this test barrel top, the end is butted on this test barrel loam cake; The position of step 3, adjustment overhead gage, snap-in force sensor and test barrel with before beginning to measure frost heave stress, are given on this test barrel in advance and are covered certain power that applies; Record frost heave stress by force transducer after step 4, the concrete frost heave, and convert corresponding electric signal output to.
Before step 1, also comprise step: be used for evenly coating release agent on the test barrel inwall of concrete formation; Then with the inside surface of plastic sheeting lining in test barrel.
This method of testing also comprises: step 5, this electric signal is amplified by signal amplifier, be presented on the Displaying Meter then.
This method of testing also comprises: step 6, the test barrel loam cake of opening test barrel and test barrel lower cover, take out the concrete after testing.
A kind of concrete early stage frost heave stress test device of the present invention and method of testing by above technical scheme, can test out concrete when enduring cold in early days, and inside concrete produces frost heave stress owing to water freezing expands, and has reached beneficial technical effects.
Description of drawings
Fig. 1 is the cut-open view of concrete early stage frost heave stress test device of the present invention;
Fig. 2 is the principle schematic of stage frost heave stress test method of the present invention.
Embodiment
For the present invention can be understood better, below will lift preferred embodiment and also be elaborated in conjunction with the accompanying drawings.
Stress test device of the present invention is in order to the early stage frost heave stress of measurement concrete, and the measurement early concrete is in subzero temperature situation lower volume situation of change.Fig. 1 is the cut-open view of concrete frost heave stress test device of the present invention, and as shown in the figure, stress test device of the present invention comprises a portal frame 1, and this portal frame 1 mainly is made up of 11, one lower baffle plates 12 of an overhead gage and two supports 13.Last lower baffle plate is separately fixed at the two ends of support 13, forms a hollow frame, with anchorage force sensor 2 and test barrel 3.Adopt lock nut 14 or other mobilizable connected modes between overhead gage 11 and the two stands 13, so that can adjust the position of overhead gage as required up and down.
During test, test barrel 3 places on the lower baffle plate 12 of portal frame 1.Test barrel 3 comprises the test barrel body 31 of cylindrical hollow, test barrel body 31 both ends opens, test barrel loam cake 32 can be covered on test barrel body 31 top opening parts, and test barrel lower cover 33 is covered on test barrel body 31 lower opening places, makes the ccontaining concrete cavity of test barrel 3 inner formation.Owing to be not easy after the concrete setting to take out, so the equal up and down opening of test barrel 3 is tested the test barrel loam cake 32 and test barrel lower cover 33 that can open test barrel 3 after finishing, the convenient concrete that will solidify takes out.
Force transducer 2 places on the test barrel 3, and the end 21 of force transducer 2 is closely against on the test barrel loam cake 32.Semiconductor strain gauge is located at the inside of force transducer 2, links to each other with end 21, by end 21 variable quantity of external force is passed to semiconductor strain gauge and detects.
Force transducer 2 is to be the force cell of elastic beam with the metal bar.Evenly paste four semiconductor strain gauges vertically on the face of cylinder of elastic beam, two arm formed bridge respectively, two half-bridges are respectively applied for each axial component and measure.
The lead of force transducer 2 passes the sensor conductor hole 111 on the overhead gage 11, is connected to signal amplifier, and signal amplifier connects Displaying Meter.The detected electric signal of semiconductor strain gauge after the signal amplifier amplification, sends Displaying Meter demonstration and mensuration to.
When utilizing concrete early stage frost heave stress test device actual measurement of the present invention, comprise the steps:
At first, on test barrel 3 inwalls that are used for concrete formation, evenly coat release agent; Then with plastic sheeting lining inside surface in test barrel, with reduce concrete endure cold when expanding and test barrel between friction force, thereby can be so that concrete free expansion, the error that reduces to measure.
In the laboratory, concrete is stirred (going into tube) moulding by match ratio after, for being 20 ± 2 ℃ in temperature, relative humidity is precuring 6 hours in 〉=90% the environment in temperature; To fill concrete test barrel 3 then and add the test barrel upper and lower covers, and put into the portal frame 1 that places refrigerator in advance, the principle of pressing Fig. 1 is with test barrel 3, and portal frame 1 and force transducer 2 are assembled together.
Adjust the position of overhead gage 11, snap-in force sensor 2 and test barrel 3 with before beginning to measure frost heave stress, apply certain power to test specimen in advance.(since in the concrete of some match ratio admixture freeze-point depressant, the liquid of inside concrete may not reach the freezing point corresponding the measurement under the temperature, frost heave can not take place, even because subzero temperature generation shrinkage.Therefore, before beginning to measure frost heave stress, need to apply certain power to test specimen in advance.)
Concrete sample is under the subzero temperature, and reaching the freezing point with its internal freedom water promptly begins to freeze, and test specimen begins frost heave.After the frost heave, external force acts on the carrying position of overhead gage 11, and overhead gage 11 will produce a strain value.Semiconductor strain gauge detects this strain value, converts corresponding resistance change to.The output of metering circuit will be exported corresponding electric signal with the size variation of external force thus, promptly mechanical signal be transformed for electric signal.
Electric signal needs to amplify through signal amplifier, passes to Displaying Meter by data line, is shown and mensuration by Displaying Meter.The input voltage of Displaying Meter is 220V, and the input voltage of force transducer and signal amplifier is 15V, and voltage is imported by transformer.As shown in Figure 2, be the principle schematic of stage frost heave stress test method of the present invention.
Preferred in the present embodiment, the column diameter of portal frame is 20mm, high 370mm, and the long 200mm of overhead gage, wide 50mm, thick 20mm, the long 200mm of lower baffle plate, wide 130mm, thick 20mm, the diameter of wire guide are 20mm; The diameter 70mm of sensor, high 125mm, degree of accuracy is 5/10000, measurement range 0-3 ton; The test barrel external diameter 108mm that is used for shaping test piece, internal diameter 94mm, high 150mm; The thick 20mm of the loam cake of test barrel, the thick 10mm of lower cover.
The above description of this invention is illustrative, and nonrestrictive, and those skilled in the art is understood, and can carry out many modifications, variation or equivalence to it within spirit that claim limits and scope, but they will fall within the scope of protection of the present invention all.

Claims (6)

1, a kind of concrete early stage frost heave stress test device is characterized in that, comprises
Portal frame, this portal frame mainly are made up of support and the overhead gage and the lower baffle plate that are separately fixed at these support two ends;
Test barrel comprises the test barrel body of a cylindrical hollow, and test barrel body top opening, test barrel loam cake are covered on this test barrel body top opening part, and this test barrel places on this lower baffle plate;
Force transducer places between this test barrel and this overhead gage, and the end of this force transducer pushes against this test barrel loam cake.
2, concrete early stage frost heave stress test device as claimed in claim 1 is characterized in that, this force transducer is to be the force cell of elastic beam with the metal bar.Evenly paste four semiconductor strain gauges vertically on the face of cylinder of elastic beam, two arm formed bridge respectively, two half-bridges are respectively applied for each axial component and measure.
3, concrete early stage frost heave stress test device as claimed in claim 2 is characterized in that, also comprises a signal amplifier, and an end is electrically connected this force transducer, and the other end is electrically connected a Displaying Meter.
4, a kind of stage frost heave stress test method is characterized in that, comprises the steps:
Step 1, the concrete for preparing being packed in the test barrel, is 20 ± 2 ℃ in temperature, and relative humidity is precuring 6 hours in 〉=90% the environment;
Step 2, will fill concrete test barrel and add the test barrel upper and lower covers, and put into the portal frame that places refrigerator in advance, and this force transducer is placed this test barrel top, the end is butted on this test barrel loam cake;
The position of step 3, adjustment overhead gage, snap-in force sensor and test barrel with before beginning to measure frost heave stress, are given on this test barrel in advance and are covered certain power that applies;
Record frost heave stress by force transducer after step 4, the concrete frost heave, and convert corresponding electric signal output to.
5, stage frost heave stress test method as claimed in claim 4 is characterized in that, also comprises step before step 1: be used for evenly coating release agent on the test barrel inwall of concrete formation; Then with the inside surface of plastic sheeting lining in test barrel.
6, stage frost heave stress test method as claimed in claim 5 is characterized in that, also comprises:
Step 5, this electric signal is amplified by signal amplifier, be presented on the Displaying Meter then.
CNA2009101481987A 2009-06-25 2009-06-25 Concrete early stage frost heave stress test device and test method CN101586993A (en)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102108716A (en) * 2011-03-25 2011-06-29 长春工程学院 Instrument for determining freezing-pulling force of pile
CN102890036A (en) * 2012-10-23 2013-01-23 朱占元 Test method for detecting kinetic parameter of artificial polycrystalline ice
CN103743626A (en) * 2014-02-08 2014-04-23 浙江大学 Test apparatus and test method for reinforced concrete beam freeze thawing durability
CN103868638A (en) * 2014-03-27 2014-06-18 水利部交通运输部国家能源局南京水利科学研究院 Frost heaving force measuring device and method
CN104316671A (en) * 2014-10-10 2015-01-28 同济大学 Test device for measuring frost heaving force and frost heaving capacity of artificial frozen-thawed soil
CN107607238A (en) * 2017-08-25 2018-01-19 南京工业大学 A kind of stress measurement device and measuring method
CN108050983A (en) * 2017-10-27 2018-05-18 中国石油天然气集团公司 A kind of test device and method for cement concrete frost-heaving deformation under different temperatures
CN108106992A (en) * 2017-12-19 2018-06-01 中建材中岩科技有限公司 Test about Bond Strength method under the conditions of the infiltration of coating material pressure

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102108716A (en) * 2011-03-25 2011-06-29 长春工程学院 Instrument for determining freezing-pulling force of pile
CN102108716B (en) * 2011-03-25 2012-08-22 长春工程学院 Instrument for determining freezing-pulling force of pile
CN102890036A (en) * 2012-10-23 2013-01-23 朱占元 Test method for detecting kinetic parameter of artificial polycrystalline ice
CN103743626A (en) * 2014-02-08 2014-04-23 浙江大学 Test apparatus and test method for reinforced concrete beam freeze thawing durability
CN103868638A (en) * 2014-03-27 2014-06-18 水利部交通运输部国家能源局南京水利科学研究院 Frost heaving force measuring device and method
CN103868638B (en) * 2014-03-27 2016-01-20 水利部交通运输部国家能源局南京水利科学研究院 Frost force measurement device and measuring method thereof
CN104316671A (en) * 2014-10-10 2015-01-28 同济大学 Test device for measuring frost heaving force and frost heaving capacity of artificial frozen-thawed soil
CN104316671B (en) * 2014-10-10 2016-05-18 同济大学 A kind of experimental rig that measures artificial freeze thawing soil frost-heave force and frost heaving amount
CN107607238A (en) * 2017-08-25 2018-01-19 南京工业大学 A kind of stress measurement device and measuring method
CN108050983A (en) * 2017-10-27 2018-05-18 中国石油天然气集团公司 A kind of test device and method for cement concrete frost-heaving deformation under different temperatures
CN108106992A (en) * 2017-12-19 2018-06-01 中建材中岩科技有限公司 Test about Bond Strength method under the conditions of the infiltration of coating material pressure

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Open date: 20091125