CN103630675A - Device and method for measuring early-age anti-cracking property of concrete under end restraint - Google Patents
Device and method for measuring early-age anti-cracking property of concrete under end restraint Download PDFInfo
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- CN103630675A CN103630675A CN201310580822.7A CN201310580822A CN103630675A CN 103630675 A CN103630675 A CN 103630675A CN 201310580822 A CN201310580822 A CN 201310580822A CN 103630675 A CN103630675 A CN 103630675A
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Abstract
The invention discloses a device and a method for measuring an early-age anti-cracking property of concrete under end restraint. The device is characterized in that an end restraint frame is made of reinforced concrete, the reinforced concrete is internally provided with four I-shaped structural steels, and multiple clamps are successively arranged on an inner side surface of the end restraint frame; one side surface of a steel plate is provided with the clamps, the clamps are provided with grooves the sections of which are trapezoidal and are integrally cast by cast iron, and the steel plate is connected with the other inner side surface of the end restraint frame; a load transducer is arranged between the steel plate and the end restraint frame, test specimens are positioned every two adjacent clamps, strain gages are pasted on the surfaces of test specimen reinforcing bars in the test specimens, the strain gages and the load transducer are connected with a strain acquisition instrument, the surfaces of the test specimens are provided with vibrating wire gages, the vibrating wire gages and a vibrating wire frequency instrument are connected, and the strain acquisition instrument and the vibrating wire frequency instrument are connected with a computer. The device disclosed by the invention has the advantages that the structure is simple, the disassembly is convenient, and the early-age anti-cracking property of concrete under the end restraint is measured in a real-time manner.
Description
Technical field
The present invention relates to a kind of device and method of measuring concrete cracking resistance in length of time morning under end restraint, belong to concrete construction field.
Background technology
In field of civil engineering, early the length of time (mainly refer to concreting after 28 days), crack resistant steel concrete performance was extremely important, measure under the effect of contraction of end different ratio of reinforcement concrete early the length of time cracking resistances to evaluating concrete early-age cracking performance and avoiding early-age concrete structure to occur that crack has very important significance.
Current end restraint device generally can only be measured the early stage cracking resistance of single test specimen, and tool is not comparative, and mostly is shaped steel and is spliced, and can not provide enough large rigidity to carry out confined concrete test specimen.The friction force of conventional brace is too large, larger on the impact of test.
Summary of the invention
In order to realize above-mentioned technical matters, the present invention is by the following technical solutions: comprise end restraint framework, load transducer, fixture, steel plate, vibratory strain ga(u)ge, foil gauge, vibratory string frequency recorder, computer, strain acquirement instrument, armored concrete test specimen, end restraint framework is reinforced concrete structure, reinforced concrete inside is provided with four i shaped steels, i shaped steel is connected with i shaped steel, a plurality of fixtures are arranged on a medial surface of end restraint framework successively, a plurality of fixtures are arranged on respectively on the side of a plurality of steel plates near fixture, on fixture, to have cross section be trapezoidal groove and adopt cast iron monoblock cast, the fixture of end restraint framework two sides is corresponding one by one, one end of load transducer is connected with the another side of steel plate, the other end of load transducer is connected with another medial surface of end restraint framework, the fixture clamping armored concrete test specimen of end restraint framework two sides, foil gauge is pasted on test specimen arrangement of reinforcement surface in armored concrete test specimen, foil gauge and load transducer are connected with strain acquirement instrument, armored concrete test specimen surface is provided with vibratory strain ga(u)ge, vibratory strain ga(u)ge is connected with vibratory string frequency recorder, strain acquirement instrument and vibratory string frequency recorder are connected with computer.
Preferably: armored concrete test specimen is built in splicing punching block, and punching block medial surface and bottom are provided with polyfluortetraethylene plate, between the bottom of fixture and polyfluortetraethylene plate, are provided with carbon dust.
Proving installation of the present invention method of testing used is as follows:
The first step: assembling end restraint framework, a plurality of fixtures are arranged on the medial surface in end restraint framework successively, fixture is arranged on a side of steel plate, on the another side of steel plate, load transducer is installed, load transducer is connected with another medial surface of end restraint framework, assembling punching block, places polyfluortetraethylene plate in punching block medial surface and bottom, between the bottom of fixture and polyfluortetraethylene plate, spill carbon dust;
Second step: the test specimen arrangement of reinforcement that posts foil gauge is arranged in template, and foil gauge is connected with strain acquirement instrument, casting concrete, after concrete initial set, arranges vibratory strain ga(u)ge on armored concrete test specimen surface;
The 3rd step: load transducer is connected to strain acquirement instrument, and strain acquirement instrument is connected to computer, the lip-deep vibratory strain ga(u)ge of reinforced concrete test specimen is connected to vibratory string frequency recorder, vibratory string frequency recorder is connected with computer.
Beneficial effect: in apparatus of the present invention, constraint realizes in two ways, the one, the end restraint of rigid frame to test specimen, the 2nd, the internal constraint of arrangement of reinforcement to test specimen.In different armored concrete test specimen inside, can arrange the reinforcing bar of different-diameter varying number, can under equal conditions study the impact of test specimen arrangement of reinforcement on early stage cracking resistance.The feature of proving installation of the present invention is simple in structure, convenient disassembly, and assembling is simple, easy to operate, tests required instrument less, can measure the early stage cracking resistance of different ratio of reinforcement concrete samples under the effect of contraction of end simultaneously.
Accompanying drawing explanation
Fig. 1 is the overall schematic of proving installation of the present invention.
Fig. 2 is the I-I sectional view of the end restraint framework of proving installation of the present invention.
Fig. 3 is II-II sectional view of the end restraint framework of proving installation of the present invention.
Fig. 4 is the vertical view of the fixture of proving installation of the present invention.
Fig. 5 is the outboard profile of the fixture of proving installation of the present invention.
Reference numeral is as follows: 1, I i shaped steel; 2, II i shaped steel; 3, III i shaped steel; 4, IV i shaped steel; 5, end restraint framework; 6, fixture; 7, load transducer; 8, high-strength bolt I; 9, nut; 10, steel plate; 11, welding reinforcement; 12, test specimen arrangement of reinforcement; 13, high-strength bolt II; 14, vibratory strain ga(u)ge; 15, foil gauge; 16, vibratory string frequency recorder; 17, computer; 18, strain acquirement instrument; 19, armored concrete test specimen; 20, high-strength bolt III; 21, fixture.
Embodiment
As shown in the figure: a kind of device of measuring concrete cracking resistance in length of time morning under end restraint, comprises end restraint framework 5, load transducer 7, fixture 6,21, steel plate 10, vibratory strain ga(u)ge 14, foil gauge 15, vibratory string frequency recorder 16, computer 17, strain acquirement instrument 18, armored concrete test specimen 19.End restraint framework 5 is reinforced concrete frame, reinforced concrete inside is provided with I i shaped steel 1, II i shaped steel 2, III i shaped steel 3, IV i shaped steel 4, I i shaped steel 1 is connected by high-strength bolt III 20 with II i shaped steel 2, IV i shaped steel 4, and III i shaped steel 3 is connected by high-strength bolt III 20 with II i shaped steel 2, IV i shaped steel 4.If the arrangement of reinforcement in end restraint framework 5 is reinforcing bar: the compressional stiffness (EA) of comparing axial I i shaped steel 1 and III i shaped steel 3 with reinforcing bar is larger, for end restraint framework 5 provides larger axial compression resistance rigidity; The bendind rigidity (EI) of comparing II i shaped steel 2 and IV i shaped steel 4 with reinforcing bar is larger, for end restraint framework 5 provides larger bendind rigidity, so whole end restraint framework 5 can provide Complete Bind.The medial surface (the left inside side in Fig. 1) that a plurality of fixtures 6 are fixedly mounted on end restraint framework 5 successively by high-strength bolt I8 is upper, that is to say that a plurality of fixtures 6 are connected with a medial surface of end restraint framework 5 successively.Steel plate 10 is provided with fixture 21 on the side near fixture 6, and fixture 21 is connected with steel plate 10 by high-strength bolt II 13.One end of load transducer 7 is connected with the another side of steel plate 10, the other end of load transducer 7 is connected with another medial surface (right side in Fig. 1) of end restraint framework 5, that is to say that a plurality of steel plates 10 are arranged on another medial surface in end restraint framework 5.The place that load transducer 7 is connected with steel plate 10 is also provided with welding reinforcement 11, to strengthen the strength of joint of load transducer 7 and steel plate 10.On fixture 6,21, having cross section is trapezoidal groove, fixture 6 the above dovetail groove narrow one facing to fixture 21, fixture 21 the above dovetail groove narrow one facing to fixture 6, fixture 6,21 adopts cast iron monoblock casts, fixture 6 is corresponding one by one with fixture 21.It is in order better to clamp armored concrete test specimen 19 that the cross section of the groove on fixture 6,21 adopts trapezoidal.Armored concrete test specimen 19 is between fixture 6 and fixture 21.The surrounding of armored concrete test specimen 19 is provided with splicing punching block, and armored concrete test specimen 19 is all built in splicing punching block.Punching block medial surface and bottom are provided with polyfluortetraethylene plate, thereby reduce the friction between armored concrete test specimen 19 and steel form, and not form removal can be tested.The bottom of fixture 6,21 contacts with the polyfluortetraethylene plate on punching block bottom surface, between the bottom of fixture 6,21 and polyfluortetraethylene plate, is provided with carbon dust.Fixture 6,21 bottoms are provided with carbon dust to reduce the friction force between fixture and punching block.Place after polyfluortetraethylene plate bottom at punching block, and the bottom of fixture 6,21 contacts with polyfluortetraethylene plate.The good test specimen arrangement of reinforcement 12 of arrangement of reinforcement is positioned in splicing punching block, on test specimen arrangement of reinforcement 12 surfaces, paste foil gauge 15, the wire of foil gauge 15 is connected with strain acquirement instrument 18, then casting concrete, after concrete initial set, on armored concrete test specimen 19 surfaces, arrange vibratory strain ga(u)ge 14, and vibratory strain ga(u)ge 14 is connected with vibratory string frequency recorder 16.Strain acquirement instrument 18 and vibratory string frequency recorder 16 are connected with computer 17.Owing to being all provided with fixture 21 on plurality of steel plates 10, and fixture 6 is corresponding one by one with fixture 21, therefore end restraint framework 5 is interior can place a plurality of armored concrete test specimens 19, that is to say that a plurality of armored concrete test specimens 19 are between a plurality of fixtures one to one 6 and fixture 21.So can arrange vertically the test specimen arrangement of reinforcement 12 of the different ratios of reinforcement and different-diameter in a plurality of armored concrete test specimens 19, by identical end restraint, complete test, the impact of the arrangement of reinforcement of test specimen arrangement of reinforcement 12 of studying the different ratios of reinforcement and different-diameter on the early stage cracking resistance of concrete.Load transducer 7 is used for measuring in real time the differential contraction stress of armored concrete test specimen 19.Vibratory strain ga(u)ge 14 is used for surveying the strain of concrete surface.Foil gauge 15 is used for measuring in real time reinforcing bar strain.
The method step adopting according to said apparatus is as follows:
The first step: assembling end restraint framework 5, a plurality of fixtures 6 are arranged on the medial surface in end restraint framework 5 successively, fixture 21 is arranged on a side of steel plate 10, load transducer 7 is installed on the another side of steel plate 10, load transducer 7 is connected with another inner side of end restraint framework 5, assembling punching block, places polyfluortetraethylene plate in punching block side and bottom, below fixture 6, spills carbon dust;
Second step: the test specimen arrangement of reinforcement 12 that posts foil gauge 15 is arranged in template, and foil gauge 15 is connected with strain acquirement instrument 18, casting concrete, after concrete initial set, arranges vibratory strain ga(u)ge 14 on reinforced concrete test specimen 19 surfaces;
The 3rd step: load transducer 7 is connected to strain acquirement instrument 18, and strain acquirement instrument 18 is connected to computer 17, the lip-deep vibratory strain ga(u)ge 14 of reinforced concrete test specimen 19 is connected to vibratory string frequency recorder 16, and vibratory string frequency recorder 16 is connected with computer 17.Measure in real time reinforcing bar strain, concrete shrinkage power and concrete surface strain.
Claims (3)
1. a device of measuring concrete cracking resistance in length of time morning under end restraint, is characterized in that: comprise end restraint framework (5), load transducer (7), fixture (6, 21), steel plate (10), vibratory strain ga(u)ge (14), foil gauge (15), vibratory string frequency recorder (16), computer (17), strain acquirement instrument (18), armored concrete test specimen (19), end restraint framework (5) is reinforced concrete structure, reinforced concrete inside is provided with four i shaped steels (1, 2, 3, 4), i shaped steel (1, 3) with i shaped steel (2, 4) be connected, a plurality of fixtures (6) are arranged on a medial surface of end restraint framework (5) successively, and a plurality of fixtures (21) are arranged on respectively a plurality of steel plates (10) near on a side of fixture (6), fixture (6, 21) on, to have cross section be trapezoidal groove and adopt cast iron monoblock cast, fixture (6) is corresponding one by one with fixture (21), one end of load transducer (7) is connected with the another side of steel plate (10), the other end of load transducer (7) is connected with another medial surface of end restraint framework (5), fixture (6) and fixture (21) clamping armored concrete test specimen (19), foil gauge (15) is pasted on test specimen arrangement of reinforcement (12) surface in armored concrete test specimen (19), foil gauge (15) and load transducer (7) are connected with strain acquirement instrument (18), armored concrete test specimen (19) surface is provided with vibratory strain ga(u)ge (14), vibratory strain ga(u)ge (14) is connected with vibratory string frequency recorder (16), strain acquirement instrument (18) and vibratory string frequency recorder (16) are connected with computer (17).
2. device according to claim 1, it is characterized in that: armored concrete test specimen (19) is all built in splicing punching block, punching block medial surface and bottom are provided with polyfluortetraethylene plate, between the bottom of fixture (6,21) and polyfluortetraethylene plate, are provided with carbon dust.
3. the method for testing of device according to claim 2, is characterized in that:
The first step: assembling end restraint framework (5), a plurality of fixtures (6) are arranged on the medial surface in end restraint framework (5) successively, fixture (21) is arranged on a side of steel plate (10), load transducer (7) is installed on the another side of steel plate (10), load transducer (7) is connected with another medial surface of end restraint framework (5), assembling punching block, at punching block medial surface and bottom, place polyfluortetraethylene plate, below fixture (6,21), spill carbon dust;
Second step: the test specimen arrangement of reinforcement (12) that posts foil gauge (15) is arranged in template, and foil gauge (15) is connected with strain acquirement instrument (18), casting concrete, after concrete initial set, arranges vibratory strain ga(u)ge (14) on armored concrete test specimen (19) surface;
The 3rd step: load transducer (7) is connected to strain acquirement instrument (18), and strain acquirement instrument (18) is connected to computer, the lip-deep vibratory strain ga(u)ge of reinforced concrete test specimen (19) (14) is connected to vibratory string frequency recorder (16), vibratory string frequency recorder (16) is connected with computer (17).
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| Application Number | Priority Date | Filing Date | Title |
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| CN201310580822.7A CN103630675A (en) | 2013-11-19 | 2013-11-19 | Device and method for measuring early-age anti-cracking property of concrete under end restraint |
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| CN201310580822.7A CN103630675A (en) | 2013-11-19 | 2013-11-19 | Device and method for measuring early-age anti-cracking property of concrete under end restraint |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104154855A (en) * | 2014-07-31 | 2014-11-19 | 桂林理工大学 | Concrete structure strain measurement method |
| CN112549303A (en) * | 2020-12-06 | 2021-03-26 | 三亚华盛新混凝土有限公司 | Processing equipment of C15 recycled concrete |
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| CN1558201A (en) * | 2004-01-19 | 2004-12-29 | 哈尔滨工业大学 | Concrete early shrinkage stress tester |
| CN2857009Y (en) * | 2005-07-13 | 2007-01-10 | 同济大学 | Constrained contraction testing machine for concrete |
| CN201035000Y (en) * | 2007-04-27 | 2008-03-12 | 同济大学 | Concrete active constraint shrinkage test machine |
| CN202562922U (en) * | 2012-05-11 | 2012-11-28 | 河海大学 | Test device for measuring early-age anti-crack performance of layered pouring concrete |
| CN202770832U (en) * | 2012-08-24 | 2013-03-06 | 河海大学 | Testing device for conducting real-time measurement on cracking time and cracking width of concrete at early stage |
-
2013
- 2013-11-19 CN CN201310580822.7A patent/CN103630675A/en active Pending
Patent Citations (5)
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|---|---|---|---|---|
| CN1558201A (en) * | 2004-01-19 | 2004-12-29 | 哈尔滨工业大学 | Concrete early shrinkage stress tester |
| CN2857009Y (en) * | 2005-07-13 | 2007-01-10 | 同济大学 | Constrained contraction testing machine for concrete |
| CN201035000Y (en) * | 2007-04-27 | 2008-03-12 | 同济大学 | Concrete active constraint shrinkage test machine |
| CN202562922U (en) * | 2012-05-11 | 2012-11-28 | 河海大学 | Test device for measuring early-age anti-crack performance of layered pouring concrete |
| CN202770832U (en) * | 2012-08-24 | 2013-03-06 | 河海大学 | Testing device for conducting real-time measurement on cracking time and cracking width of concrete at early stage |
Non-Patent Citations (3)
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| A.BENTUR和K.KOVLER: "Evaluation of early age cracking characteristics in cementitious systems", 《MATERIALS AND STRUCTURES》 * |
| YA WEI和WILL HANSEN: "Tensile creep behavior of concrete subject to constant restraint at very early age", 《JOURNAL OF MATERIALS IN CIVIL ENGINEERING》 * |
| 候景鹏: "钢筋混凝土早龄期约束收缩性能研究", 《中国优秀博士论文全文数据库 工程科技Ⅱ》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104154855A (en) * | 2014-07-31 | 2014-11-19 | 桂林理工大学 | Concrete structure strain measurement method |
| CN112549303A (en) * | 2020-12-06 | 2021-03-26 | 三亚华盛新混凝土有限公司 | Processing equipment of C15 recycled concrete |
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Application publication date: 20140312 |