CN111122646A - Concrete self-contraction deformation and thermal expansion coefficient measuring device and measuring method - Google Patents
Concrete self-contraction deformation and thermal expansion coefficient measuring device and measuring method Download PDFInfo
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Abstract
The invention discloses a device and a method for measuring self-contraction deformation and thermal expansion coefficient of concrete, wherein the device comprises: the lining template comprises lining plates attached to the periphery of the inner wall of the mold and a polytetrafluoroethylene layer on the bottom surface of the inner side of the mold, and pore channels are respectively arranged at two ends of the mold; the displacement testing system comprises a data acquisition module, a measuring head, a displacement sensor and a guide rod, wherein the measuring head, the displacement sensor and the guide rod are arranged corresponding to each pore channel; the temperature control system comprises a temperature sensor, a temperature control soft body layer and a temperature control module, wherein the temperature sensor is embedded into concrete in a pre-buried mode, the temperature control soft body layer is attached to the inner side of the lining template, a plastic film is further attached to the inner side of the lining template, and the temperature control module collects and controls the temperature of the temperature control soft body layer in real time.
Description
Technical Field
The invention relates to the field of civil engineering materials, in particular to a device and a method for measuring self-contraction deformation and thermal expansion coefficient of concrete.
Background
The problem of concrete cracking has not been solved at all but has not been avoided. Modern high performance concrete requires high durability of concrete, but the generation of cracks is inevitably detrimental to the durability of concrete. The cracks provide a way for external substances (such as various ions, water, air and the like) to corrode the concrete, the substances can initiate various reactions to accelerate the quality degradation of the concrete and the corrosion of the reinforcing steel bars, and the quality degradation of the concrete can accelerate the processes, so that the service life of the structure is greatly shortened and the durability is reduced due to the existence of the cracks. From the analysis of the mechanical principle of concrete crack generation, the reason that the concrete crack generation is caused is that the tensile strength is lower than the tensile stress. The factors causing the tensile stress of the concrete are various, such as loading action, constraint deformation, local stress and the like, but most cracks are caused by non-loading factors, and the most important factors in the non-loading factors are concrete shrinkage and temperature deformation. Therefore, the research on the self-contraction deformation and the thermal expansion coefficient of the early-age concrete has important significance for avoiding the cracking of the early-age concrete and improving the durability of the concrete.
As the cementing material is in a rapid hydration process, the early-age concrete has larger hydration heat, and simultaneously has larger self-shrinkage deformation caused by chemical shrinkage, and the self-shrinkage deformation and the temperature deformation of the early-age concrete exist at the same time. However, the following difficulties exist in measuring the self-shrinkage deformation and temperature deformation of early-age concrete: (1) the self-shrinkage deformation and the temperature deformation of the early-age concrete are difficult to peel; (2) the self-shrinkage deformation and the thermal expansion coefficient of early-age concrete may also be related to the hydration temperature of the concrete; (3) the cement hydration is started from the moment of adding water, so the real self-contraction deformation and the thermal expansion coefficient of the concrete are measured before the initial setting of the concrete. Only by simultaneously realizing the three points, the self-shrinkage deformation and the temperature deformation of the early-age concrete can be accurately measured. The existing measuring device and measuring method are difficult to realize. The measurement methods disclosed in patents CN101701925A, CN101865865A, CN202066814U, CN101000338A, CN103558246A, CN108181346A and CN108226215A can only measure the thermal expansion coefficient of the hardened concrete, but cannot measure the thermal expansion coefficient of the fresh concrete in the ultra-early age from the pouring time. The measurement methods disclosed in the CN102608152A and CN103293179A patents make the actual temperature inside the concrete different from the ambient temperature, that is, there is a temperature gradient field inside the concrete, so that the calculated temperature difference is not a real temperature difference, and the measurement methods do not peel off and shrink. In the CN102435631A measuring device, the concrete directly contacts the mould, and the concrete cannot be freely deformed. The CN101482526A patent discloses a method for measuring the thermal expansion coefficient of early-age concrete, which considers that the hydration reaction of the cementing material is inhibited and the self-shrinkage is eliminated in the temperature range of-2 to 3 ℃, so the deformation is simple temperature deformation. However, the actual thermal expansion of concrete does not occur at about-2 to 3 ℃, which is not consistent with the actual situation.
In summary, it can be seen that how to accurately measure the self-shrinkage deformation and the thermal expansion coefficient of the early-age concrete due to the disadvantages and deficiencies of the existing measuring device and measuring method, a more accurate measuring device and measuring method are provided, and the difficult problems to be solved in the art are to deeply research the physical characteristics of the early-age concrete and improve the crack resistance and durability of the concrete.
Disclosure of Invention
In order to solve the above technical problems, the present invention provides a device for measuring self-contraction deformation and thermal expansion coefficient of concrete, comprising:
the mould system for forming the concrete test piece comprises a mould and a lining template, wherein the mould is a square container with an opening at the upper part, the lining template comprises a liner plate which is attached to the periphery of the inner wall of the mould and can be drawn out and a polytetrafluoroethylene layer which covers the bottom surface of the inner side of the mould, and a pair of opposite two ends of the mould are respectively provided with a pore passage which penetrates through the side wall of the mould;
the displacement testing system comprises a data acquisition module, and a measuring head, a displacement sensor and a guide rod which are arranged corresponding to each pore channel, wherein the measuring head and the pore channels are embedded at the end part of the concrete test piece correspondingly, one end of the guide rod penetrates through the pore channels to be connected with the measuring head, the other end of the guide rod is connected with the displacement sensor, and the data acquisition module is connected with the displacement sensor;
temperature control system, including temperature sensor, temperature control software layer and temperature control module, temperature sensor buries inside the concrete when concrete placement, the soft layer of temperature control is flexible and temperature adjustable's software material, and the inboard at inside lining form is attached to the soft layer of temperature control, and enough covers concrete sample top surface, and still attach the plastic film that has the enough cover concrete sample top surface of one deck in the inboard on the soft layer of temperature control, the soft layer of temperature control with temperature control module connects, and temperature control module gathers temperature sensor's temperature in real time to the temperature on the soft layer of control temperature control is controlled.
The invention also provides a concrete self-contraction deformation measuring method, which adopts the concrete self-contraction deformation and thermal expansion coefficient measuring device to measure the concrete self-contraction deformation, and comprises the following steps:
s11, sequentially installing a lining template, a temperature control soft body layer and a plastic film in a mould, and then installing a measuring head and a guide rod, wherein one end of the guide rod penetrates through a pore channel to be connected with the measuring head;
s12, pouring concrete on the inner side of the plastic film, and embedding a temperature sensor in the center of the concrete sample during pouring;
s13, vibrating the concrete, wrapping the concrete with a plastic film to cover and seal the concrete, wrapping a temperature control soft body layer outside the plastic film, installing a displacement sensor, connecting the displacement sensor with a data acquisition module, connecting the temperature sensor with a temperature control module, and drawing out a lining plate in the mold;
s14, monitoring the internal temperature T1 of the concrete through a temperature control module, controlling the temperature T2 of a temperature control soft body layer at the same time, and enabling the internal temperature T1 of the concrete to be in a constant state all the time by adjusting the temperature T2 of the temperature control soft body layer;
and S15, taking the sum of the displacement deformation measured by the displacement sensor as the self-contraction deformation of the early-age concrete without temperature deformation.
The invention also provides a concrete thermal expansion coefficient measuring method, which adopts the concrete self-contraction deformation and thermal expansion coefficient measuring device to measure the thermal expansion coefficient and comprises the following steps:
s11, sequentially installing a lining template, a temperature control soft body layer and a plastic film in a mould, and then installing a measuring head and a guide rod, wherein one end of the guide rod penetrates through a pore channel to be connected with the measuring head;
s12, pouring concrete on the inner side of the plastic film, and embedding a temperature sensor in the center of the concrete sample during pouring;
s13, vibrating the concrete, wrapping the concrete with a plastic film to cover and seal the concrete, wrapping a temperature control soft body layer outside the plastic film, installing a displacement sensor, connecting the displacement sensor with a data acquisition module, connecting the temperature sensor with a temperature control module, and drawing out a lining plate in the mold;
s16, monitoring the internal temperature T1 of the concrete through a temperature control module, simultaneously controlling the temperature T2 of a soft body layer through adjusting the temperature to enable the internal temperature of the concrete test piece to reach and stabilize at the temperature T2, recording the displacement measured by a displacement sensor at the moment as S1, then increasing the temperature T2 of the temperature control soft body layer to T2+ delta T, and simultaneously controlling the temperature T2 of the soft body layer through adjusting the temperature to enable the internal temperature of the concrete test piece to reach and stabilize at T2+ delta T, and recording the displacement at the moment as S2;
s17, calculating a thermal expansion coefficient α c according to the following formula,
αc＝(S2-S1)/ΔT。
compared with the existing measuring device and measuring method, the invention has the beneficial effects that:
1. the invention can start measurement when concrete is poured, which is particularly important for the thermal expansion coefficient of concrete.
2. The invention can control the temperature of the concrete rapidly in real time through the temperature control soft body layer, so that the temperature of the concrete is always in the target temperature range, and the measured self-contraction deformation is not influenced by the self-hydration heat of the concrete.
3. Because the thermal expansion coefficient of the concrete is possibly related to the age and the hydration temperature of the concrete, the temperature of the test piece can be changed in a short time through the temperature control soft body layer, the thermal deformation of the test piece is measured in real time, and the thermal expansion coefficient of the concrete at the target age and the target temperature is calculated.
4. The invention can not only measure the self-contraction deformation and the thermal expansion coefficient of the concrete, but also control the internal temperature of the concrete by changing the temperature control soft body layer so as to measure the drying contraction of the concrete at different temperatures.
5. The invention has simple manufacture, clear measurement principle and convenient operation, and can monitor the concrete deformation and control the concrete temperature in real time by adopting software for acquisition and control.
Drawings
The above features and technical advantages of the present invention will become more apparent and readily appreciated from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.
FIG. 1 is a schematic longitudinal cross-sectional view of a measuring device;
FIG. 2 is a top view of the measuring device;
FIG. 3 is a schematic view of a concrete specimen coated with a plastic film and a temperature control soft body layer;
FIG. 4 is a curve of the internal temperature of the concrete of the first test piece and the second test piece along with the change of the age of the concrete in the early age;
FIG. 5 is a self-contraction deformation curve of early-age concrete of test piece I and test piece II;
FIG. 6 is a graph of the coefficient of thermal expansion of concrete at early age as a function of age.
The figure includes: measuring head 1, displacement sensor 2, inside lining template 3, welt 31, polytetrafluoroethylene layer 32, mould 4, polytetrafluoroethylene layer 5, temperature control soft body layer 6, temperature sensor 7, temperature sensor installation pipe 8, guide arm 9, concrete sample 10, plastic film 11, data acquisition module 20, temperature control module 30, pore 41.
Detailed Description
Embodiments of a concrete self-contraction deformation and thermal expansion coefficient measuring apparatus and a measuring method according to the present invention will be described below with reference to the accompanying drawings. Those of ordinary skill in the art will recognize that the described embodiments can be modified in various different ways, or combinations thereof, without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims. Furthermore, in the present description, the drawings are not to scale and like reference numerals refer to like parts.
As shown in fig. 1 and 2, a concrete self-contraction deformation and thermal expansion coefficient measuring apparatus includes: a set of mould system for casting and molding concrete to be measured; the displacement test system is used for measuring the deformation of the concrete test piece; and the temperature control system is used for measuring and controlling the temperature of the concrete sample.
The mould system comprises a mould 4 and a lining template 3, wherein the mould 4 is a long-strip-shaped container with an opening at the upper part, and a rim extending outwards is arranged around the upper end of the mould for holding the mould. The lining form 3 comprises a lining plate 31 attached to the periphery of the inner wall of the mold 4 and capable of being pulled out, and a polytetrafluoroethylene layer 32 covering the bottom surface of the inner side of the mold, and a pore 41 penetrating through the side wall of the mold is respectively arranged at the center positions of two ends of the mold 4 in the length direction. The term "stick" means to adhere to the surface of the substrate, and does not mean to stick the substrate. In addition, the present embodiment does not limit the mold to be a long strip, and may be, for example, a rectangle or a square.
The displacement testing system comprises a measuring head 1, a displacement sensor 2, a guide rod 9 and a data acquisition module 20, wherein the measuring head 1, the displacement sensor 2 and the guide rod 9 are arranged corresponding to each pore channel 41. The measuring head 1 is pre-embedded at the end part of the concrete test piece corresponding to the pore channel, one end of the guide rod 9 is used for penetrating the pore channel to be connected with the measuring head 1, and the other end of the guide rod is connected with the displacement sensor 2. Preferably, the guide rod 9 is detachably connected with the measuring head 1, the displacement sensors 2 are arranged at two ends of the length direction, the measuring ends of the displacement sensors 2 prop against the guide rod 9, the measuring direction of the displacement sensors 2 is coaxial with the length direction of the mold, the data acquisition module 20 is connected with the displacement sensors 2, acquires data of the displacement sensors 2 in real time, and calculates the deformation of the concrete sample in real time.
The temperature control system comprises a temperature sensor 7, a temperature control soft body layer 6 and a temperature control module 30, wherein the temperature sensor 7 is embedded in concrete when the concrete is poured, the temperature control soft body layer 6 is a deformable and temperature-adjustable soft body material, such as an electric blanket with a condenser pipe, namely, the temperature control soft body layer 6 can deform along with the deformation of the concrete. After the arrangement of the mould system is finished, lining the temperature control soft body layer 6 in the mould, namely attaching the temperature control soft body layer 6 to the inner side of the lining template 3, and attaching a layer of plastic film 11 to the inner side of the temperature control soft body layer 6. The temperature control soft body layer 6 is electrically connected to the temperature control module 30, and a program for controlling the temperature of the temperature control soft body layer 6 is provided in the temperature control module 30. The temperature control module 30 collects the temperature of the temperature sensor 7 in real time and controls the temperature of the temperature control soft body layer 6.
The method for measuring the self-contraction deformation and the thermal expansion coefficient of the concrete adopts the device for measuring the self-contraction deformation and the thermal expansion coefficient of the concrete. The measurement method is illustrated below in two examples.
The first embodiment is as follows: early self-shrinkage deformation measurement of concrete
The cement used in the concrete of the embodiment is P.O 42.5 ordinary portland cement; the fly ash is first-grade low-calcium ash, and the water demand ratio is 95 percent; the water reducing agent is PCA-I type polycarboxylic acid high-performance water reducing agent, and the solid content is 30%; the fine aggregate is river sand, the fineness modulus is 2.6, the fine aggregate belongs to medium sand, and the mud content is less than 1%; the used coarse aggregate is limestone macadam with the grain size of 5-20 mm in continuous gradation.
The concrete mixture ratio is 240kg/m3 of cement, 60kg/m3 of fly ash, 186kg/m3 of water, 750kg/m3 of fine aggregate and 1150kg/m3 of coarse aggregate. The 28-day strength of the concrete used was 37 MPa.
By adopting the measuring device, the measuring method comprises the following steps:
s11, in the mold 4, firstly installing the polytetrafluoroethylene layer 32 and the lining plate 31, then installing the temperature control soft body layer 6, attaching a layer of plastic film 11 to the inner side of the temperature control soft body layer 6, and finally installing the measuring head 1 and the guide rod 9, wherein one end of the guide rod 9 penetrates through the pore channel to be connected with the measuring head;
s12, concrete is poured into the mold 4, specifically, the inner side of the plastic film 11. A temperature sensor mounting pipe 8 is pre-buried in the center of a concrete sample during pouring, and the temperature sensor mounting pipe 8 is used for mounting a temperature sensor 7;
s13, pouring and vibrating concrete, sealing the concrete by using a plastic film 11 (as shown in figure 3, the plastic film 11 wraps and covers the whole concrete), then wrapping a temperature control soft body layer 6 on the periphery and the top surface of the outer side of the plastic film 11, then installing a temperature sensor 7 and a displacement sensor 2, installing the temperature sensor 7 in a temperature sensor installation pipe 8, connecting the displacement sensor 2 with a data acquisition module 20, connecting the temperature sensor with a temperature control module 30, and finally extracting a lining plate 31 in the mold;
s14, forming two groups of test pieces, namely a test piece I and a test piece II, simultaneously according to the methods of the steps S11 to S13. The temperature control module 30 is used for monitoring the internal temperature T1 of the concrete, controlling the temperature T2 of the temperature control soft body layer 6 at the same time, and adjusting the temperature T2 of the temperature control soft body layer 6 to enable the internal temperature T1 of the concrete to be always in a constant state (the constant state means that the variation amplitude is less than +/-0.5 ℃); for the second test piece, only the internal temperature T1 of the concrete is monitored, the temperature T2 of the temperature control soft body layer 6 is not controlled, and the function of the second test piece is mainly compared with the change curve of the temperature T1 of the first test piece along with the age so as to illustrate the beneficial effects of the embodiment, which is not necessary for the measurement method.
And S15, the sum of the displacement deformation of the displacement sensor 2 of the first test piece is the self-contraction deformation of the early-age concrete, and the temperature deformation is not contained.
Fig. 4 is a curve of the internal temperature T1 of the first and second concrete samples in the early age according to the age, and fig. 5 is a curve of the self-contraction deformation of the first and second concrete samples in the early age. As can be seen from fig. 4, since the temperature of the soft body layer 6 is not controlled by the temperature control of the second test piece so that the internal temperature T1 of the concrete is kept constant, a temperature peak occurs inside the concrete in an early age, which causes thermal expansion deformation of the concrete, and the self-contraction deformation measured by the second test piece is not true self-contraction deformation. The self-contraction deformation measurement result in fig. 5 also shows that the deformation curves of the first test piece and the second test piece are different, and the expansion deformation of the second test piece is larger. Therefore, the first embodiment shows that the self-shrinkage deformation of the concrete in the early age does not contain temperature deformation.
It should be noted that the expansion at the beginning of the curve in fig. 5 is caused by the slight collapse of the concrete after the liner 31 is withdrawn before the initial setting of the concrete.
Example two: measurement of early thermal expansion coefficient of concrete
The concrete raw materials and the mixing ratio used in the second embodiment are the same as those in the first embodiment, and the description is not repeated. By adopting the measuring device, the measuring method comprises the following steps:
s11, in the mold 4, firstly installing the polytetrafluoroethylene layer 32 and the lining plate 31, then installing the temperature control soft body layer 6, attaching a layer of plastic film 11 to the inner side of the temperature control soft body layer 6, and finally installing the measuring head 1 and the guide rod 9, wherein one end of the guide rod 9 penetrates through the pore channel to be connected with the measuring head;
s12, pouring concrete in the mould 4, and embedding a temperature sensor installation pipe 8 in the center of the concrete sample during pouring, wherein the temperature sensor installation pipe 8 is used for installing a temperature sensor 7;
s13, after concrete is poured and vibrated, the concrete is sealed by a plastic film 11 (as shown in figure 3, the plastic film 11 wraps and covers the whole concrete), then a temperature control soft body layer 6 is wrapped on the periphery and the top surface of the outer side of the plastic film 11, a temperature sensor 7 and a displacement sensor 2 are installed, the temperature sensor 7 is installed in a temperature sensor installation pipe 8, the displacement sensor 2 is connected with a data acquisition module 20, the temperature sensor is connected with a temperature control module 30, and finally a lining plate 31 in the mold is drawn out;
s16, monitoring the internal temperature T1 of the concrete through the temperature control module 30, controlling the temperature T2 of the temperature control soft body layer 6, stabilizing the internal temperature of the concrete within a target temperature range by adjusting the temperature T2 of the temperature control soft body layer 6, specifically, stabilizing the internal temperature of the concrete to T2, and recording the displacement measured by the displacement sensor at this time as S1.
When the temperature T2 of the temperature-controlled soft body layer 6 was further increased to T2+ Δ T, the internal temperature of the concrete was observed, and when the internal temperature of the concrete was also stabilized to T2+ Δ T, the displacement at that time was recorded as S2.
S17, calculating a thermal expansion coefficient α c according to the following formula (1):
αc＝(S2-S1)/ΔT (1)
the temperature control soft body layer 6 can control the temperature change in the concrete in a short time, so that the temperature gradient does not exist in the concrete, and the thermal expansion deformation of the concrete is accurately measured. Meanwhile, the internal expansion coefficient change of the concrete in different ages can be tested for the same test piece. FIG. 6 is a graph showing the thermal expansion coefficient of concrete used in the examples as a function of age.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A concrete self-contraction deformation and thermal expansion coefficient measuring device is characterized by comprising:
the mould system for forming the concrete test piece comprises a mould and a lining template, wherein the mould is a square container with an opening at the upper part, the lining template comprises a liner plate which is attached to the periphery of the inner wall of the mould and can be drawn out and a polytetrafluoroethylene layer which covers the bottom surface of the inner side of the mould, and a pair of opposite two ends of the mould are respectively provided with a pore passage which penetrates through the side wall of the mould;
the displacement testing system comprises a data acquisition module, and a measuring head, a displacement sensor and a guide rod which are arranged corresponding to each pore channel, wherein the measuring head and the pore channels are embedded at the end part of the concrete test piece correspondingly, one end of the guide rod penetrates through the pore channels to be connected with the measuring head, the other end of the guide rod is connected with the displacement sensor, and the data acquisition module is connected with the displacement sensor;
temperature control system, including temperature sensor, temperature control software layer and temperature control module, temperature sensor buries inside the concrete when concrete placement, the soft layer of temperature control is flexible and temperature adjustable's software material, and the inboard at inside lining form is attached to the soft layer of temperature control, and enough covers concrete sample top surface, and still attach the plastic film that has the enough cover concrete sample top surface of one deck in the inboard on the soft layer of temperature control, the soft layer of temperature control with temperature control module connects, and temperature control module gathers temperature sensor's temperature in real time to the temperature on the soft layer of control temperature control is controlled.
2. The apparatus for measuring self-contraction deformation and thermal expansion coefficient of concrete according to claim 1,
the mould is a long-strip-shaped container, and the pore passages are located at two ends of the mould in the length direction.
3. The apparatus for measuring self-contraction deformation and thermal expansion coefficient of concrete according to claim 1,
the guide rod is detachably connected with the measuring head.
4. The apparatus for measuring self-contraction deformation and thermal expansion coefficient of concrete according to claim 1,
the concrete test piece is characterized in that a temperature sensor installation pipe is further arranged, the lower portion of the temperature sensor installation pipe is embedded in the concrete test piece, a hole is formed in the lower portion of the temperature sensor installation pipe, and the temperature sensor is installed in the temperature sensor installation pipe.
5. A method for measuring the self-contraction deformation of concrete by using the concrete self-contraction deformation and thermal expansion coefficient measuring device of any one of claims 1 to 4, comprising the following steps:
s11, sequentially installing a lining template, a temperature control soft body layer and a plastic film in a mould, and then installing a measuring head and a guide rod, wherein one end of the guide rod penetrates through a pore channel to be connected with the measuring head;
s12, pouring concrete on the inner side of the plastic film, and embedding a temperature sensor in the center of the concrete sample during pouring;
s13, vibrating the concrete, wrapping the concrete with a plastic film to cover and seal the concrete, wrapping a temperature control soft body layer outside the plastic film, installing a displacement sensor, connecting the displacement sensor with a data acquisition module, connecting the temperature sensor with a temperature control module, and drawing out a lining plate in the mold;
s14, monitoring the internal temperature T1 of the concrete through a temperature control module, controlling the temperature T2 of a temperature control soft body layer at the same time, and enabling the internal temperature T1 of the concrete to be in a constant state all the time by adjusting the temperature T2 of the temperature control soft body layer;
and S15, determining the sum of the displacement deformation measured by the displacement sensor as the self-contraction deformation of the early-age concrete without temperature deformation.
6. The method for measuring self-contraction deformation of concrete according to claim 5,
the constant state in S14 means that the temperature variation amplitude is less than ± 0.5 ℃.
7. The method for measuring self-contraction deformation of concrete according to claim 5,
in step S12, when concrete is poured into the mold, a temperature sensor mounting pipe is pre-embedded in the concrete sample, a lower portion of the temperature sensor mounting pipe is pre-embedded in the concrete sample, a hole is formed in the lower portion of the temperature sensor mounting pipe, and then a temperature sensor is mounted in the temperature sensor mounting pipe.
8. A method for measuring the coefficient of thermal expansion of concrete, which is characterized in that the device for measuring the coefficient of thermal expansion by self-contraction deformation and coefficient of thermal expansion of concrete as claimed in any one of claims 1 to 4 is used for measuring the coefficient of thermal expansion, and comprises the following steps:
s11, sequentially installing a lining template, a temperature control soft body layer and a plastic film in a mould, and then installing a measuring head and a guide rod, wherein one end of the guide rod penetrates through a pore channel to be connected with the measuring head;
s12, pouring concrete on the inner side of the plastic film, and embedding a temperature sensor in the center of the concrete sample during pouring;
s13, vibrating the concrete, wrapping the concrete with a plastic film to cover and seal the concrete, wrapping a temperature control soft body layer outside the plastic film, installing a displacement sensor, connecting the displacement sensor with a data acquisition module, connecting the temperature sensor with a temperature control module, and drawing out a lining plate in the mold;
s16, monitoring the internal temperature T1 of the concrete through a temperature control module, simultaneously controlling the temperature T2 of a soft body layer through adjusting the temperature to enable the internal temperature of the concrete test piece to reach and stabilize at the temperature T2, recording the displacement measured by a displacement sensor at the moment as S1, then increasing the temperature T2 of the temperature control soft body layer to T2+ delta T, and simultaneously controlling the temperature T2 of the soft body layer through adjusting the temperature to enable the internal temperature of the concrete test piece to reach and stabilize at T2+ delta T, and recording the displacement at the moment as S2;
s17, calculating a thermal expansion coefficient α c according to the following formula,
αc＝(S2-S1)/ΔT。
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113654927A (en) * | 2021-07-21 | 2021-11-16 | 深圳前海砼源建设科技有限公司 | Method for judging cracking resistance of concrete through net slurry free deformation test |
| CN114646753A (en) * | 2021-12-24 | 2022-06-21 | 中铁二十四局集团有限公司 | Concrete expansion and shrinkage deformation testing system in curing period |
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