Concrete shrinkage and evaporation rate testing device capable of controlling constant temperature and humidity

Abstract

The invention discloses a concrete shrinkage and evaporation rate testing device capable of controlling constant temperature and humidity, which comprises a cube acrylic shell (7) and is characterized in that four top ends of the cube acrylic shell (7) are connected with one end of a tension sensor (2) in a hanging manner; the other end of the tension sensor (2) is connected with an upper computer; a water absorption kit (1) is arranged above the cube acrylic shell (7); heating resistors (3) are arranged on the left side and the right side of the cube acrylic shell (7); a humidifier (6) is arranged on the left side of the left heating resistor (3); a temperature and humidity sensor (5) is arranged on the back surface of the cube acrylic shell (7); a plurality of shrinkage testers (4) are arranged at the bottom of the cube acrylic shell (7); a suspended iron plate (8) is arranged below the cube acrylic shell (7), and the cube acrylic shell (7) is in air connection with the suspended iron plate (8); the device is light, easy to operate, convenient to move, high in cost performance and environmentally friendly, and the built-in water absorption kit can be replaced.

Description

Technical Field

[0001] The invention relates to the technical field of concrete material testing, and in particular to a concrete shrinkage and evaporation rate testing device capable of controlling constant temperature and humidity. Background Art

[0002] The evaporation rate of concrete is the key basis for judging whether concrete is cracked, so it is particularly important to measure the instantaneous evaporation rate of concrete. The evaporation rate is usually measured by weighing method: the concrete is placed in a constant temperature and humidity instrument, and the concrete is taken out at a certain interval for weighing. The reduced mass is the mass of the lost water, and then the rate of water evaporation is determined. This method itself has many loopholes, such as: the weighing interval is long, and the instantaneous evaporation rate cannot be recorded in real time. When the specimen is taken out, the ambient temperature, humidity and other factors suddenly change due to the contact of concrete with the outside air. In addition, the mass change of the specimen cannot exclude the interference of moisture in the air on the evaporation of the specimen or the mass loss caused by collision when taking it out, so there is a certain deviation in the result. Therefore, the concrete evaporation curve measured by the above method cannot accurately reflect the change of the real evaporation rate of concrete. There are also automatic testers for concrete evaporation rate in existing inventions and creations. Such instruments use a balance to measure the mass of concrete. This method can only measure the mass of concrete water reduction, but cannot measure the specific evaporation rate. Only some of these devices and methods can be used on-site construction sites, some of which cannot reflect the actual evaporation rate, or the instruments are expensive and inconvenient to move, and cannot achieve fully automated testing. The measurement of concrete evaporation rate and shrinkage is affected by many factors such as mix ratio and environmental factors. The current testing instruments do not have the ability to test evaporation and shrinkage at the same time, and also lack the advantages of accuracy and automation, making it difficult to meet the testing requirements.

[0003] It is of great significance to study the shrinkage cracking and early maintenance mechanism and measures of concrete to clarify the influence of environmental factors on the proportion of various types of early shrinkage of concrete, as well as to explore the relationship between the total shrinkage of concrete and environmental factors, and the relationship between the evaporation rate of concrete and environmental factors. However, there is currently no scientific and complete method or instrument to accurately determine the evaporation rate corresponding to each reaction stage of early hydration of concrete, nor can it directly measure or calculate the proportion of each type of shrinkage. In addition, existing instruments cannot directly measure the influence of various environmental factors on the evaporation rate and shrinkage. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a concrete shrinkage and evaporation rate testing device that controls constant temperature and humidity, so as to overcome the inaccuracy and impracticability of existing concrete shrinkage and evaporation test analysis methods.

[0005] Technical solution: The concrete shrinkage and evaporation rate testing device for controlling constant temperature and humidity described in the present invention comprises a cubic acrylic shell, and the four top ends of the cubic acrylic shell are suspended and connected to one end of a tension sensor; the other end of the tension sensor is connected to a host computer; a water absorption test kit is provided above the cubic acrylic shell; heating resistors are provided on the left and right sides of the cubic acrylic shell; a humidifier is provided on the left side of the left heating resistor; a temperature and humidity sensor is provided on the back of the cubic acrylic shell; a plurality of shrinkage testers are provided at the bottom of the cubic acrylic shell; a suspended iron plate is provided below the cubic acrylic shell, and the cubic acrylic shell and the suspended iron plate are connected by air.

[0006] Furthermore, the tension sensor is used to record the overall tension change and the water evaporation rate and curve.

[0007] Furthermore, the heating resistor is used to adjust the temperature and control the test conditions.

[0008] Furthermore, the shrinkage tester is used to measure the shrinkage of concrete / mortar and is connected to the host computer through a wire.

[0009] Furthermore, the temperature and humidity sensor is used to monitor the temperature and humidity changes in the measuring instrument. When the humidity temperature is lower than / higher than the set threshold, the switch is turned on to ensure constant temperature and humidity in the test.

[0010] Furthermore, a humidifier is used to ensure constant test humidity.

[0011] Furthermore, the cube acrylic shell is used to ensure a closed test environment, and a sealing tape is adhered to the lower side and coated with oil to ensure airtightness.

[0012] Furthermore, the suspended iron plate is used to ensure a closed environment and ensure that the shrinkage test instrument is not disturbed by ground vibration.

[0013] The method for testing the shrinkage and evaporation rate of concrete by controlling constant temperature and humidity of the present invention comprises the following steps:

[0014] (1) Set the raw materials and proportions;

[0015] (2) After placing cement mortar and concrete into the shrinkage tester respectively, adjust the temperature and humidity humidifier and heating resistor to the specified temperature and humidity, and add an appropriate amount of quicklime reagent into the water absorption test kit;

[0016] (3) Connect the tension sensor and temperature and humidity sensor to the host computer to transmit data in real time;

[0017] (4) After closing the device, tape is pasted on the gap and oil is applied to seal it. At the same time, a control test of the same group is carried out. The two results are subtracted to eliminate the influence of moisture in the air. At the same time, the control test group eliminates drying shrinkage;

[0018] (5) The measurement result is the evaporation curve of the concrete hydration shrinkage reaction, and the data tested by the shrinkage tester is the mortar under the set temperature and humidity environment; or the water in the mortar or concrete is replaced with an equal volume of anhydrous ethanol to test the concrete drying shrinkage and evaporation curve of the concrete during the anhydrous reaction.

[0019] Furthermore, a control test was conducted by wrapping the shrinkage instrument with tin foil.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the device of the present invention can change the environmental conditions, realize the controllable temperature and humidity conditions, measure the evaporation of concrete and generate a real-time curve, which is convenient for exploring the influence of factors such as temperature and humidity on the evaporation rate of concrete. By measuring the evaporation rate of concrete and its corresponding curve under specified environmental conditions, the evaporation rate of concrete can be accurately measured, which solves the problem of inaccuracy in the current measurement of the evaporation rate of the concrete surface. Compared with the existing measuring instruments, the interference factors of the measurement environment are eliminated, and the temperature and humidity are controllable, so that the evaporation rate measurement under multiple environmental conditions can be realized, ensuring that the test conditions are rigorous and scientific, and the test data are true and reliable. The device is light and easy to operate, easy to move, and cost-effective. The built-in water absorption test kit can be replaced, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The device of the present invention;

[0022] Figure 2 is a flow chart of the method of the present invention;

[0023] Figure 3 This is an image of the contraction instrument data of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0025] like Figure 1 As shown, an embodiment of the present invention provides a concrete shrinkage and evaporation rate testing device for controlling constant temperature and humidity, comprising a cubic acrylic shell 7, wherein four top ends of the cubic acrylic shell 7 are suspended and connected to one end of a tension sensor 2; the other end of the tension sensor 2 is connected to a host computer; a water absorption reagent kit 1 is arranged above the cubic acrylic shell 7; heating resistors 3 are arranged on the left and right sides of the cubic acrylic shell 7; a humidifier 6 is arranged on the left side of the left heating resistor 3; a temperature and humidity sensor 5 is arranged on the back of the cubic acrylic shell 7; a plurality of shrinkage testers 4 are arranged at the bottom of the cubic acrylic shell 7; a suspended iron plate 8 is arranged below the cubic acrylic shell 7, and the cubic acrylic shell 7 and the suspended iron plate 8 are connected by air.

[0026] Among them, the tension sensor 2 is used to record the overall tension change, record the water evaporation rate and curve. The heating resistor 3 is used to adjust the temperature and control the test conditions. The shrinkage tester 4 is used to measure the shrinkage of concrete / mortar and is connected to the host computer through a wire. The temperature and humidity sensor 5 is used to monitor the temperature and humidity changes in the measuring instrument. When the humidity temperature is lower than / higher than the set threshold, the switch is turned on to ensure constant temperature and humidity in the test. The humidifier 6 is used to ensure constant test humidity. The cube acrylic shell 7 is used to ensure a closed test environment. The lower side is adhered with sealing tape and oiled to ensure airtightness. The suspended iron plate 8 is used to ensure a closed environment to ensure that the shrinkage test instrument is not disturbed by ground vibration.

[0027] like Figure 2 As shown, the embodiment of the present invention provides a method for testing the shrinkage and evaporation rate of concrete by controlling constant temperature and humidity. Before the experiment begins, turn on the temperature and humidity sensor and the control switch and set the temperature and humidity thresholds (the test experiment uses 85%-95% 22℃-25℃), turn on the humidifier and the heating resistor, replace the quicklime reagent (1KG) in the test kit, put the cement mortar / concrete into the shrinkage tester, and then place the shrinkage tester on the iron plate. After debugging, connect the wire, and connect the other end of the wire to the test terminal. Debug the tension sensor and connect it to the computer, adjust the distance between the acrylic box and the bottom (about 1cm), stick tape and oil on the gap, and straighten and fix the rope connected to the tension tester. The following steps are included:

[0028] (1) The raw materials and proportions are as follows: Cement: C42.5, compressive strength is 26.4 and 50.7 MPa respectively; concrete mix ratio (kg / m3) water: cement: fly ash: mineral powder: sand: coarse aggregate: water reducing agent = 185:355:45:30:773:1024:5.16

[0029] (2) After placing cement mortar and concrete into the shrinkage tester respectively, adjust the temperature and humidity humidifier and heating resistor to the specified temperature and humidity, and add an appropriate amount of quicklime reagent into the water absorption test kit;

[0030] (3) Connect the tension sensor and temperature and humidity sensor to the host computer to transmit data in real time;

[0031] (4) After closing the device, tape is pasted on the gap and oil is applied to seal it. At the same time, a control test of the same group is carried out. The two results are subtracted to eliminate the influence of moisture in the air. At the same time, the control test group eliminates drying shrinkage;

[0032] (5) The measurement result is the evaporation curve of the concrete hydration shrinkage reaction, and the data tested by the shrinkage tester is the mortar under the set temperature and humidity environment; or the water in the mortar or concrete is replaced with an equal volume of anhydrous ethanol to test the concrete drying shrinkage and the evaporation curve of the concrete when there is no hydration reaction. The control test is to wrap the shrinkage instrument with tin foil and conduct the test.

[0033] Specific test process: The test group is shown in Table 1. The shrinkage of mortar / concrete is tested normally at the specified temperature and humidity, and the absorption rate of concrete and moisture in the air is tested at the same time. The test is divided into a control group and a test group, and the control group is divided into two parts. Control group 1 uses tin foil to wrap the shrinkage tester to prevent moisture evaporation, and the other elements are the same as the test group. Control group 1 is compared with the test group to eliminate the interference of moisture in the air on the test results of the test group samples. The net evaporation of moisture in the test group can be obtained by subtracting the test data of group 1 from the tensile sensor data of the test group. The shrinkage measured by control group 1 is the total amount of other shrinkages excluding drying shrinkage. Control group 2 uses anhydrous ethanol instead of water in mortar or concrete to prevent the hydration reaction of the sample, and the other elements are the same as the test group. Control group 2 can obtain the total amount of shrinkage other than chemical shrinkage. By comparing control group 2 with the test group, the evaporation of water corresponding to chemical reactions at different ages can be effectively analyzed, and the chemical shrinkage, drying shrinkage ratio, and the relationship between shrinkage and evaporation rate can also be accurately obtained. In addition, the current shrinkage of concrete is measured by the shrinkage tester to generate a real-time curve such as Figure 3 As shown, it reflects the shrinkage change of concrete more intuitively.

[0034]

Claims

1. A device for testing the shrinkage and evaporation rate of concrete under constant temperature and humidity, comprising a cubic acrylic shell (7), characterized in that: The four top ends of the cube acrylic shell (7) are suspended and connected to one end of the tension sensor (2); the other end of the tension sensor (2) is connected to a host computer; a water absorption test kit (1) is provided above the cube acrylic shell (7); heating resistors (3) are provided on the left and right sides of the cube acrylic shell (7); a humidifier (6) is provided on the left side of the left heating resistor (3); a temperature and humidity sensor (5) is provided on the back of the cube acrylic shell (7); a plurality of shrinkage testers (4) are provided at the bottom of the cube acrylic shell (7); a suspended iron plate (8) is provided below the cube acrylic shell (7), and the cube acrylic shell (7) and the suspended iron plate (8) are connected by air.

2. A device for testing concrete shrinkage and evaporation rate with constant temperature and humidity according to claim 1, characterized in that: The tension sensor (2) is used to record the overall tension change and the water evaporation rate and curve.

3. The device for testing concrete shrinkage and evaporation rate under constant temperature and humidity control according to claim 1, characterized in that: The heating resistor (3) is used to adjust the temperature and control the test conditions.

4. The device for testing concrete shrinkage and evaporation rate by controlling constant temperature and humidity according to claim 1, characterized in that: The shrinkage tester (4) is used to measure the shrinkage of concrete / mortar and is connected to the host computer via a wire.

5. The device for testing concrete shrinkage and evaporation rate under constant temperature and humidity control according to claim 1, characterized in that: The temperature and humidity sensor (5) is used to monitor the temperature and humidity changes in the measuring instrument. When the humidity temperature is lower than / higher than a set threshold, the switch is turned on to ensure constant temperature and humidity in the test.

6. The device for testing concrete shrinkage and evaporation rate under constant temperature and humidity control according to claim 1, characterized in that: The humidifier (6) is used to ensure constant test humidity.

7. The device for testing concrete shrinkage and evaporation rate under constant temperature and humidity control according to claim 1, characterized in that: The cube acrylic shell (7) is used to ensure a closed test environment, and a sealing tape is adhered to the lower side and coated with oil to ensure airtightness.

8. The device for testing concrete shrinkage and evaporation rate under constant temperature and humidity control according to claim 1, characterized in that: The suspended iron plate (8) is used to ensure a closed environment and ensure that the shrinkage test instrument is not disturbed by ground vibration.

9. A method for testing the shrinkage and evaporation rate of concrete by controlling constant temperature and humidity, characterized in that: The following steps are involved: (1) Set the raw materials and proportions; (2) After placing cement mortar and concrete into the shrinkage tester respectively, adjust the temperature and humidity humidifier and heating resistor to the specified temperature and humidity, and add an appropriate amount of quicklime reagent into the water absorption test kit; (3) Connect the tension sensor and temperature and humidity sensor to the host computer to transmit data in real time; (4) After closing the device, tape is pasted on the gap and oil is applied to seal it. At the same time, a control test of the same group is carried out. The two results are subtracted to eliminate the influence of moisture in the air. At the same time, the control test group eliminates drying shrinkage; (5) The measurement result is the evaporation curve of the concrete hydration shrinkage reaction, and the data tested by the shrinkage tester is the mortar under the set temperature and humidity environment; or the water in the mortar or concrete is replaced with an equal volume of anhydrous ethanol to test the concrete drying shrinkage and evaporation curve of the concrete during the anhydrous reaction.

10. The device for testing concrete shrinkage and evaporation rate by controlling constant temperature and humidity according to claim 1, characterized in that: The control test was conducted by wrapping the shrinkage instrument with tin foil.

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