Cement-based material anti-cracking automatic detection device and detection method

Abstract

The present application relates to the field of construction engineering, in particular to a cement-based material anti-cracking automatic detection equipment and method, which comprises a base, an outer constraint ring and an inner constraint ring coaxially arranged on the base, and the outer constraint ring and the inner constraint ring enclose a ring space for sample pouring; the outer ring of the inner constraint ring is provided with a stress concentration seat in the vertical direction, the cross section of the stress concentration seat is in a right angle shape, and the right angle tip of the stress concentration seat faces the outer constraint ring direction. The present application can accurately and quickly automatically detect the anti-cracking performance of the cement-based material, and can realize comprehensive evaluation of the anti-cracking performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of construction engineering, in particular to a cement-based material anti-cracking automatic detection equipment and detection method. BACKGROUND

[0002] Concrete, mortar is the most common cement-based material, for example, the anti-cracking performance of concrete is a comprehensive performance, which has certain relationship with tensile strength, ultimate tensile deformation capacity, tensile elastic modulus, autogenous volume deformation, creep, thermal performance, and the anti-cracking performance will directly affect the integrity and durability of the building.

[0003] In order to measure the anti-cracking performance of cement-based material, the anti-cracking performance of cement-based material can be evaluated by measuring the cracking sample and the length and width of the crack through the flat plate restraint method, which has the advantages of simple measurement method, and the shrinkage cracking index of cement-based material can be obtained after 24h molding; but the accelerated water evaporation in the test process of flat plate restraint method does not conform to the practical engineering, and the repeatability of the test result is poor, lacks sufficient precision, and the evaluation index is relatively single, and the development trend of the crack cannot be comprehensively evaluated.

[0004] In order to measure the anti-cracking performance of cement-based material, the ring test method is also used, the shrinkage of cement-based material is restrained by the steel ring to generate ring tensile stress, and the early or late cracking time is used to evaluate the anti-cracking performance of cement-based material. Due to the existence of coarse aggregate in concrete, the shrinkage of cement-based material is small, and the dispersion of aggregate makes the cracks mostly present as dispersed micro-cracks, it is difficult to observe the cracks on the surface of cement-based material ring, the cracking time is late or the concrete ring sample does not crack, the overall cracking time is long, and the cracking position of the sample is random, so it is limited to evaluate the anti-cracking performance of cement-based material by the time of crack appearance and the width of crack, and the anti-cracking performance of cement-based material cannot be accurately and quickly detected. SUMMARY

[0005] In order to avoid and overcome the technical problems existing in the prior art, the present application provides a cement-based material anti-cracking automatic detection equipment and detection method. The present application can accurately and quickly automatically detect the anti-cracking performance of cement-based material, and can comprehensively evaluate the anti-cracking performance.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] A cement-based material anti-cracking automatic detection equipment and detection method, comprising a base and an outer restraint ring and an inner restraint ring coaxially arranged on the base, the outer restraint ring and the inner restraint ring form a ring-shaped space for pouring the test sample; a stress concentration seat is arranged on the outer circle of the inner restraint ring along the vertical direction, the cross section of the stress concentration seat is right angle shape, and the right angle tip of the stress concentration seat faces the direction of the outer restraint ring.

[0008] As a further scheme of the present application: the stress concentration seat is an angle steel welded with the inner constraint ring, four groups of stress concentration seats are evenly arranged along the circumference of the inner constraint ring, and the line connecting the tips of the two oppositely arranged groups of angle steels passes through the axis of the inner constraint ring.

[0009] As a further scheme of the present application: the inner diameter of the outer constraint ring is R o , the outer diameter of the inner constraint ring is R i , and R i / R o ≤1.23.

[0010] As a further scheme of the present application: the inner diameter of the outer constraint ring is 203mm, the outer diameter of the outer constraint ring is 210mm, the inner diameter of the inner constraint ring is 152.5mm, the outer diameter of the inner constraint ring is 165mm, the sectional width of the angle steel of the stress concentration seat is 60mm, the distance between the tip of the stress concentration seat and the ring surface of the inner constraint ring is 18mm, and the thickness of the angle steel of the stress concentration seat is 5mm.

[0011] As a further scheme of the present application: a ring groove is formed on the base at a corresponding position to respectively clamp and fix the outer constraint ring and the inner constraint ring.

[0012] As a further scheme of the present application: the outer constraint ring comprises two groups of half rings, and the two groups of half rings are fixed by buckling locking.

[0013] A detection method, characterized in that it comprises the following steps:

[0014] S1, installing the cement-based material anti-cracking automatic detection equipment;

[0015] S2, after evenly applying release agent on the inner side of the outer constraint ring, pouring the test sample between the outer constraint ring and the inner constraint ring, and curing;

[0016] S3, after curing, removing the outer constraint ring, and pasting strain gauges on the outer circle of the test sample, connecting the strain gauges with the strain tester and starting sampling;

[0017] S4, calculating the cement-based material anti-cracking coefficient index ω according to the sampling data:

[0018]

[0019] Wherein, α is the constraint coefficient;

[0020] ε s (t) is the measured constraint strain at the time t when the test sample surface cracks;

[0021] ε l(t) is the dry shrinkage strain of the sample corresponding to the same age sample under the same curing condition at the time t when the sample cracks;

[0022] E c is the elastic modulus of the sample;

[0023] A c is the cross-sectional area of the sample;

[0024] E s is the elastic modulus of the inner constraint ring;

[0025] A s is the cross-sectional area of the inner constraint ring;

[0026] S5, calculate the crack resistance coefficient ω of different components of the cement-based material, and the smaller the ω value, the better the crack resistance of the cement-based material.

[0027] As a further scheme of the application: in step S2, the finished sample is covered with plastic wrap after finishing and placed in a standard curing environment for 24 hours.

[0028] As a further scheme of the application: in step S3, the hardened sample is removed to a constant temperature and humidity chamber, and the outer constraint ring is removed, and the dust and particles on the surface of the sample are cleaned after the outer constraint ring is removed; the strain gauge is connected to the strain tester in the form of 1 / 4 bridge, and the sampling frequency is 1 time / minute.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] 1、The inner and outer constraint rings of the application cooperate to form a ring-shaped area for one-time casting of the sample, and the strain gauge can be directly pasted on the outer circle of the sample after casting to test the strain, and the cracking of the cement-based material can be accelerated by arranging the stress concentration seat during testing, which greatly accelerates the cracking time of the cement-based material, shortens the test process, and the dry shrinkage and constraint strain on the surface of the sample can be tested after demolding, and the crack resistance coefficient index of the cement-based material is obtained after calculation, and the crack resistance performance of the cement-based material can be directly judged by the crack resistance coefficient index.

[0031] 2、The opening of the annular groove on the base can accurately position the inner and outer constraint rings, and ensure the uniformity of the shape of the sample; the split design of the outer constraint ring greatly accelerates the demolding speed.

[0032] 3、The application accurately, quickly and automatically detects the cracking strain of the cement-based material, and obtains the crack resistance coefficient index by combining the elastic modulus, dry shrinkage strain and other parameters of the same age sample under the same curing condition, and the crack resistance performance of the cement-based material can be comprehensively evaluated by using the crack resistance coefficient index. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a top view of the present application.

[0034] Figure 2 is a vertical section view of the present application.

[0035] Figure 3 is a comparison chart of the constraint strain curves of the C-R and C-LS group samples.

[0036] Figure 4 is a comparison chart of the drying shrinkage strain curves of the C-R and C-LS group samples.

[0037] in the figure:

[0038] 1, base;

[0039] 2, outer constraint ring; 21, buckle; 22, strain gauge;

[0040] 3, inner constraint ring; 31, stress concentration seat. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] Please refer to Figures 1-4 In the embodiments of the present application, a cement-based material anti-cracking automatic detection device and detection method comprises a base 1, which is a cylindrical seat body, and two groups of annular grooves are arranged coaxially on the top of the base 1 for fixing the inner constraint ring 3 and the outer constraint ring 2 from top to bottom.

[0043] The outer constraint ring 2 is designed in a split type for easy disassembly, and is preferably composed of two groups of half rings, which are clamped together by a clamp or locked and fixed by a buckle structure. The fixing mode is not limited. The outer constraint ring 2 and the inner constraint ring 3 are preferably made of steel ring material, and the annular region is formed between the outer constraint ring 2 and the inner constraint ring 3 for cement pouring. Before pouring, the inner circle of the outer constraint ring 2 is evenly smeared with release agent.

[0044] The inner diameter of the outer constraint ring 2 is R o The outer diameter of the inner constraint ring 3 is R i , R i / R o ≤1.23. The inner diameter of the outer constraint ring 2 is preferably 203mm, and the outer diameter of the outer constraint ring 2 is preferably 210mm; the inner diameter of the inner constraint ring 3 is preferably 152.5mm, and the outer diameter of the inner constraint ring 3 is preferably 165mm.

[0045] The stress concentration seats 31 are preferably arranged in four groups, from top to bottom, the tips of the four groups of stress concentration seats 31 are all directed towards the outer constraint ring 2, there is a square area between the four groups of stress concentration seats 31, and the four groups of stress concentration seats 31 are arranged at the four corner ends of the square area. The cross-sectional width of the angle steel of the stress concentration seat 31 is preferably 60 mm, the distance between the tip of the stress concentration seat 31 and the outer ring surface of the inner constraint ring 3 is preferably 18 mm, and the thickness of the angle steel of the stress concentration seat 31 is preferably 5 mm.

[0046] During the test, the following steps are included:

[0047] S1, install the cement-based material anti-cracking automatic detection equipment.

[0048] S2, after applying uniform release agent on the inner side of the outer constraint ring 2, adding the test sample between the outer constraint ring 2 and the inner constraint ring 3, curing after the pouring operation is completed, and then performing surface treatment on the test sample and covering it with plastic wrap, and placing it in a standard curing environment for 24 hours.

[0049] S3, after curing, remove the outer constraint ring 2, and paste strain gauges 22 on the outer circle of the test sample, connect the strain gauges 22 with the strain tester and start sampling.

[0050] The removal of the outer constraint ring 2 is carried out in a constant temperature and humidity environment, and the dust and particles on the surface of the test sample are cleaned after the outer constraint ring 2 is removed. The constant temperature and humidity environment is preferably a temperature of 20℃±2℃ and a humidity of more than 70%.

[0051] The wires of the strain gauges 22 that have been welded are connected to the strain tester in the form of a 1 / 4 bridge, ensuring that each strain gauge 22 is effectively connected; after the power is turned on, the relevant software is run on the computer, the connection channel is selected and the sampling parameters are set, among which the sampling frequency is 1 time / minute and the data length is 1440; during the strain test, the data will be automatically saved in the pre-created folder, and the time of the appearance of the surface crack of the ring-shaped test sample and the width of the crack are observed. The strain gauges 22 are pasted at a height of 1 / 2 of the test sample and are spaced 90° apart.

[0052] S4, according to the sampling data, the cement-based material anti-cracking coefficient index ω is calculated:

[0053]

[0054] Wherein, α is the constraint coefficient;

[0055] ε s (t) is the measured constraint strain at the time t when the surface of the test sample cracks;

[0056] εl (t) is the dry shrinkage strain of the same age sample under the same curing condition corresponding to the time t when the sample cracks, the measurement of the dry shrinkage strain is the prior art, and thus is not described herein.

[0057] E c is the elastic modulus of the sample;

[0058] A c is the cross-sectional area of the sample;

[0059] E s is the elastic modulus of the inner restraint ring 3;

[0060] A s is the cross-sectional area of the inner restraint ring 3;

[0061] S5, the crack resistance coefficient ω of the different component cement-based materials is calculated, and the smaller the ω value, the better the crack resistance performance of the cement-based material.

[0062] After the test is completed, the data is processed, and the surface strain of the cement-based material is plotted against time, and the crack resistance coefficient index is obtained in combination with the elastic modulus, the dry shrinkage strain and other parameters of the same age sample under the same curing condition when the sample cracks, the crack resistance coefficient ω of each component is calculated, and the smaller the ω value, the better the crack resistance performance of the cement-based material.

[0063] The two concrete mixtures in the following table are subjected to crack detection by the detection device of the present application, C-R and C-LS are existing concrete formulations, and the crack resistance performance of the concrete of the C-R formulation is better than that of the concrete of the C-LS formulation;

[0064]

[0065] By Figure 3 and Figure 4 It can be seen that the time of initial mutation of the surface strain of the C-R group concrete is 9.3h, the restrained strain is 140.08με, the dry shrinkage strain of the sample at this time under the same curing condition is 296.6με; the time of initial mutation of the surface strain of the C-LS group concrete is 9.5h, the restrained strain is 90.23με, and the dry shrinkage strain of the sample at this time under the same curing condition is 273με. The inner and outer radii of the inner restraint ring are 152.5mm and 165mm; the inner radius of the outer restraint ring is 203mm. The elastic modulus of the sample is uniformly taken as 10Gpa, the elastic modulus of the inner restraint ring is 30Gpa, and the restraint coefficient α=1.

[0066] The above data is brought into the crack resistance coefficient index calculation formula to obtain the crack resistance coefficient index ω of the C-R group concrete =1.14; the crack resistance coefficient index ω of the C-LS group concrete =1.63. The crack resistance coefficient index ω of the C-R group concrete is smaller, and the crack resistance performance of the component concrete is good, which is consistent with the actual data.

[0067] The basic principles of the application are described above in conjunction with specific embodiments, however, it should be noted that the advantages, benefits, effects and the like mentioned in the present application are only examples and are not limiting, and these advantages, benefits, effects and the like cannot be considered as necessary for each embodiment of the present application. In addition, the above-mentioned specific details are only for the purpose of example and for the purpose of understanding, and the above-mentioned details do not limit the present application to be necessarily implemented with the above-mentioned specific details.

[0068] The block diagrams of the devices, apparatuses, equipment, systems involved in the present application are only illustrative examples and are not intended to require or imply the connection, arrangement, configuration as shown in the block diagram. As those skilled in the art will recognize, these devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner. Words such as "include", "contain", "have" and the like are open-ended words, mean "including but not limited to", and can be used interchangeably. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably.

Claims

1. A method of detection, characterized in that, The method comprises the following steps: S1, installing a cement-based material anti-cracking automatic detection device; The cement-based material anti-cracking automatic detection device comprises a base (1) and an outer constraint ring (2) and an inner constraint ring (3) coaxially arranged on the base (1), and the outer constraint ring (2) and the inner constraint ring (3) enclose a ring space for pouring a test sample; a stress concentration seat (31) is arranged on the outer circle of the inner constraint ring (3) in the vertical direction, the cross section of the stress concentration seat (31) is in a right angle shape, and the sharp end of the stress concentration seat (31) faces the direction of the outer constraint ring (2); S2, after evenly applying a release agent on the inner side of the outer constraint ring (2), pouring a test sample between the outer constraint ring (2) and the inner constraint ring (3), and curing; S3, after curing, removing the outer constraint ring (2), and pasting a strain gauge (22) on the outer circle of the test sample, connecting the strain gauge (22) with a strain tester and starting sampling; S4, according to the sampling data, calculating a cement-based material anti-cracking coefficient index ω: Wherein, α is a constraint coefficient; ε s (t) is the measured constraint strain at the time t of the crack initiation on the surface of the test piece; ε l (t) is the shrinkage strain of the sample of the same age as the sample at time t when the sample cracks; E c Elastic modulus of the test specimen; A c A is the cross-sectional area of the sample; E s E is the modulus of elasticity of the inner restraining ring (3); A s A is the cross-sectional area of the inner constraint ring (3); S5, calculating the anti-cracking coefficient ω of different component cement-based materials, and the smaller the ω value, the better the anti-cracking performance of the cement-based material.

2. The method of claim 1, wherein, The stress concentration seat (31) is an angle steel fixedly welded with the inner constraint ring (3), four groups of stress concentration seats (31) are uniformly arranged along the circumference of the inner constraint ring (3), and the connecting line of the sharp ends of the two oppositely arranged angle steels passes through the axis of the inner constraint ring (3).

3. The method of claim 2, wherein, The inner diameter of the outer constraint ring (2) is 203mm, the outer diameter of the outer constraint ring (2) is 210mm; the inner diameter of the inner constraint ring (3) is 152.5mm, the outer diameter of the inner constraint ring (3) is 165mm; the cross section width of the angle steel of the stress concentration seat (31) is 60mm, the distance between the sharp end of the stress concentration seat (31) and the ring surface of the inner constraint ring (3) is 18mm, and the thickness of the angle steel of the stress concentration seat (31) is 5mm.

4. The method of any one of claims 1 to 3, wherein, The base (1) is provided with a ring groove at the corresponding position so as to respectively clamp and fix the outer constraint ring (2) and the inner constraint ring (3).

5. The method of any one of claims 1 to 3, wherein the method comprises contacting the sample with a first antibody that specifically binds to the target protein and a second antibody that specifically binds to the first antibody. The outer constraint ring (2) comprises two groups of half rings which are locked and fixed by buckles (21).

6. The method of claim 1, wherein, In step S2, after the finished test sample is treated, it is covered with plastic wrap and placed in a standard curing environment for 24 hours.

7. The method of claim 1, wherein, In step S3, after the hardened test sample is moved into a constant temperature and humidity chamber, the outer constraint ring (2) is removed, and the dust and particles on the surface of the test sample are cleaned after the outer constraint ring (2) is removed; the strain gauge (22) is connected with the strain tester in a 1 / 4 bridge mode, and the sampling frequency is 1 time / minute.

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