A method for testing the durability of prefabricated building sealants under extreme environments

Abstract

The present invention discloses a method for testing the durability of assembled building sealants under extreme environments. The present invention first prepares an I-shaped test piece, the substrate is a cement mortar board, the number of test pieces is 4 / group, each group of test pieces is embedded in an insulation board, and the test sample structure to be tested is prepared; secondly, the above-mentioned test sample structure to be tested is placed in a thermal conductivity meter, and a tensile adhesion test is performed after the simultaneous action of internal and external temperature differences, dry-wet alternation, and high and low temperature cycles. The present invention accurately simulates the cracking effect of assembled building sealants exposed to extreme environments, making the test data more accurate and reliable; the detection device of the present invention has a simple and reasonable structure, and the detection method is easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of prefabricated buildings and green building materials, and specifically relates to a method for detecting the durability of prefabricated building sealants under simulated extreme natural environments (freeze-thaw-high and low temperature-dry and wet alternating cycles). Background Art

[0002] Prefabricated buildings are a new type of building that uses prefabricated factory production of components and prefabricated on-site construction as a production method, and can integrate multiple industrial chains such as the construction industry and industry. In recent years, with the development of social economy and the transformation and upgrading of the construction industry, the vigorous promotion of national and local policies, and the promotion of multiple factors such as human resource shortages and rising labor costs, prefabricated buildings have developed rapidly in my country. In February 2016, the State Council's "Several Opinions on Further Strengthening Urban Planning and Construction Management" proposed: "Vigorously promote prefabricated buildings; strive to use about 10 years to make the proportion of prefabricated buildings in new buildings reach 30%." In 2020, the Ministry of Housing and Urban-Rural Development and 13 other departments jointly issued the "Guiding Opinions on Promoting the Coordinated Development of Intelligent Construction and Building Industrialization", proposing: "Accelerate the upgrading of building industrialization, vigorously develop prefabricated buildings, and promote the establishment of a professional, large-scale, and information-based production system based on standard components." In 2020, the Ministry of Housing and Urban-Rural Development and other departments proposed several opinions on accelerating the development of new building industrialization: "Optimize the production of components and parts, and promote prefabricated concrete buildings."

[0003] With the widespread promotion and application of prefabricated buildings, the use of prefabricated exterior wall panels is becoming more and more widespread. The outer protective structure of prefabricated buildings assembled from prefabricated exterior wall panels is prone to water seepage nodes if the assembly joints are not properly handled. In order to ensure the assembly quality of the outer protective wall panels of prefabricated buildings, the adhesion and other properties of the sealant used for the joints of the exterior walls of prefabricated buildings should meet the requirements.

[0004] Since the sealants used in prefabricated buildings are exposed to the external environment of the building, they are degraded by the external environment for a long time during the service life. Therefore, the durability of the sealant is also one of the most important performance factors. An effective sealant durability test method can guarantee the quality and long-term service performance of the sealant to a certain extent, and is one of the biggest needs of the industry. my country has a vast territory, and the climate conditions vary greatly from place to place. Some areas have severe or extreme weather. Extreme cold, high temperature, high and low temperature cycles caused by the temperature difference between day and night, alternating between dry and wet, and the temperature difference between the inside and outside of the building may affect the performance of the sealant. However, the current standards and specifications related to sealants have not fully considered the impact of harsh climate environments on the long-term performance of sealants. The test method for the durability of sealants in "Elastic Sealant for Building Windows" JC / T485 mainly considers the effects of factors such as immersion, hot pressing and cold drawing, and stretching-compression cycles; "Silicone and Modified Silicone Building Sealant" GB / T 14683 adds a test method for adhesion after ultraviolet irradiation. These methods all have certain limitations and do not consider the comprehensive effects of many factors in the natural climate environment on sealants. Summary of the invention

[0005] In order to overcome the shortcomings of the existing means for testing the durability of assembled building sealants under extreme natural environments, the present invention provides a method for testing the durability of assembled building sealants under extreme environments.

[0006] To solve the above problems, the solution of the present invention is:

[0007] The present invention provides a method for testing the durability of assembled building sealants under extreme environments, comprising:

[0008] (1) The sealant to be tested is made into an I-shaped specimen according to the requirements of "Sealant for Concrete Building Joints" JC / T 881. The base material is cement mortar board. The number of specimens is 4 per group.

[0009] (2) The above test pieces are cured under standard conditions for 28 days. After the curing is completed, each group of test pieces is embedded in an insulation board to form a test sample structure to be tested;

[0010] (3) Place the above-mentioned sample structure to be tested in a thermal conductivity meter. Set the cold plate temperature of the thermal conductivity meter to -20°C and the hot plate temperature to 20°C to simulate the indoor and outdoor temperature difference in severe cold areas in winter. Turn on the instrument, wait for the cold and hot plate temperatures to reach the set temperature, and then turn off the instrument after working for 1.5 hours. Take out the sample structure and use an oven to heat and dry it, forming a high and low temperature, dry and wet alternating cycle.

[0011] (4) Repeat the above operation (3) for 30 to 35 cycles, then remove the test piece from the insulation board and conduct a tensile adhesion test. Test the performance parameters such as maximum tensile strength, elongation at break, bonding failure area, and tensile elastic modulus of the test piece in accordance with the Test Methods for Building Sealing Materials GB / T13477.8. By analyzing the characterized parameters and the number of extreme environment simulation cycles, the feasibility of this method for testing sealant test pieces is verified, thereby selecting a sealant that meets the design requirements.

[0012] In step (1), at least three groups of test pieces are prepared; all test pieces use matching primers.

[0013] In step (2), the test piece is sprinkled with water until it is saturated with water and then embedded in the insulation board.

[0014] In step (2), the insulation board is an XPS foam insulation board of 300×300×30 mm.

[0015] In step (3), a thermal conductivity meter is used to conduct an internal and external temperature difference test on the sample structure.

[0016] The thermal conductivity meter of step (3) comprises a lifting device inside a box, two heat sinks, two temperature control systems, a hot plate, a cold plate, two temperature sensors, a cooling system and an external electronic data recording system; the sample structure to be tested is placed between the upper and lower temperature sensors, the upper temperature sensor is connected to the hot plate, the temperature control system and the heat sink in sequence, the lower temperature sensor is connected to the cold plate, the temperature control system and the heat sink in sequence, a lifting device is connected to each end of the upper heat sink, and the cooling system is connected to the upper and lower heat sinks.

[0017] In step (4), the tensile adhesion test is performed on the specimen after 0, 5, 10, 15, 20, 25, 30 and 35 cycles respectively.

[0018] The beneficial effects of the present invention are:

[0019] In order to simulate the sealant detection in a freeze-thaw environment, the present invention adds the simultaneous effects of internal and external temperature difference, dry-wet alternation, and high and low temperature cycles, more accurately simulating the cracking effect of the sealant for assembled buildings exposed to extreme environments, making the detection data more accurate and reliable. The detection device of the present invention has a simple and reasonable structure, and the detection method is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of the sample to be detected according to the present invention.

[0021] Figure 2 This is a schematic diagram of the I-shaped test piece structure of the present invention.

[0022] Figure 3Schematic diagram of the thermal conductivity meter structure.

[0023] Figure 4 It is the maximum tensile strength of the sealant specimen measured after different cycles using the detection method of the present invention.

[0024] Figure 5 It is the tensile elastic modulus of the sealant specimen measured after different cycles using the detection method of the present invention.

[0025] Figures 1 to 3 The markings are: 1 sealant, 2 cement mortar board, 3 insulation board, 4-1, 4-2 lifting device, 5-1, 5-2 heat dissipation plate, 6-1, 6-2 temperature control system, 7 hot plate, 8-1, 8-2 temperature sensor, 9 test sample structure, 10 cold plate, 11 cooling system, 12 electronic and data recording system. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific embodiments.

[0027] Example 1

[0028] The present invention provides a method for testing the durability of assembled building sealants under extreme environments, comprising:

[0029] (1) The sealant to be tested is made into I-shaped specimens according to the requirements of "Sealant for Concrete Building Joints" JC / T 881. The substrate is cement mortar board. The number of specimens is 4 per group, and 8 groups of specimens are made. All specimens are coated with matching primers;

[0030] (2) The above specimens were cured under standard conditions for 28 days. After the curing was completed, each group of specimens was sprinkled with water until saturated with water and then embedded in a 300×300×30 mm XPS foam insulation board to prepare the test specimen structure;

[0031] (3) Place the above-mentioned sample structure to be tested in a thermal conductivity meter. Set the cold plate temperature of the thermal conductivity meter to -20°C and the hot plate temperature to 20°C to simulate the indoor and outdoor temperature difference in severe cold areas in winter. Turn on the instrument, wait for the cold and hot plate temperatures to reach the set temperature, and then turn off the instrument after working for 1.5 hours. Take out the sample structure and use an oven to heat and dry it, forming a high and low temperature, dry and wet alternating cycle.

[0032] (4) Repeat the above operation (3) for 20 to 30 cycles, then remove the test piece from the insulation board and conduct a tensile adhesion test. Test the test piece's maximum tensile strength, elongation at break, bonding failure area, tensile elastic modulus and other performance parameters in accordance with "Test Methods for Building Sealing Materials" GB / T13477.8. By analyzing the characterized parameters and the number of extreme environment simulation cycles, the feasibility of this method for testing sealant test pieces is verified, thereby selecting a sealant that meets the design requirements.

[0033] The thermal conductivity meter of step (3) comprises a lifting device inside a box, two heat sinks, two temperature control systems, a hot plate, a cold plate, two temperature sensors, a cooling system and an external electronic data recording system; the sample structure to be tested is placed between the upper and lower temperature sensors, the upper temperature sensor is connected to the hot plate, the temperature control system and the heat sink in sequence, the lower temperature sensor is connected to the cold plate, the temperature control system and the heat sink in sequence, a lifting device is connected to each end of the upper heat sink, and the cooling system is connected to the upper and lower heat sinks.

[0034] After the specimens were cycled 0, 5, 10, 15, 20, 25, 30, and 35 times, the tensile adhesion test was carried out on the specimens. The maximum tensile strength and tensile modulus of the sealant specimens are shown in Figure 2. Figure 4 and Figure 5 As shown in the figure, the maximum tensile strength and tensile modulus of the specimen decreased significantly with the increase of internal and external temperature difference, dry-wet alternation, and hot-cold cycle number. The first 25 cycles had a greater impact on the tensile test results of the specimen. Therefore, this method can effectively test the durability of sealant joints in extreme environments. The actual number of test cycles can be selected as 25 to shorten the test period.

Claims

1. A method for testing the durability of assembled building sealants under extreme environments, characterized in that: include: (1) The sealant to be tested is made into an I-shaped specimen according to the requirements of "Sealant for Concrete Building Joints" JC / T 881. The base material is cement mortar board. The number of specimens is 4 per group. (2) The above test pieces are cured under standard conditions for 28 days. After the curing is completed, each group of test pieces is embedded in an insulation board to form a test sample structure to be tested; (3) Place the above-mentioned sample structure to be tested into a thermal conductivity meter. Set the cold plate temperature of the thermal conductivity meter to -20°C and the hot plate temperature to 20°C to simulate the indoor and outdoor temperature difference in winter in cold regions; Turn on the instrument, wait for the hot and cold plates to reach the set temperature, and then turn off the instrument after working for 1.5 hours. Take out the sample structure and heat it in an oven to dry it, forming a high and low temperature, dry and wet alternating cycle; (4) Repeat the operation cycle of the above step (3) for 30 to 35 cycles, remove the test piece in the sample structure from the insulation board and conduct a tensile adhesion test. Test the maximum tensile strength, elongation at break, bonding failure area, and tensile elastic modulus performance parameters of the test piece in accordance with the "Test Methods for Building Sealing Materials" GB / T13477.8; by analyzing the characterized parameters and the number of extreme environment simulation cycles, the feasibility of this method for testing sealant test pieces is verified, thereby selecting a sealant that meets the design requirements.

2. The method for testing the durability of assembled building sealants under extreme environments according to claim 1, characterized in that: In step (1), at least three groups of test pieces are prepared; all test pieces use matching primers.

3. The method for testing the durability of assembled building sealants under extreme environments according to claim 1, characterized in that: In step (2), the test piece is sprinkled with water until it is saturated with water and then embedded in the insulation board.

4. The method for testing the durability of assembled building sealants under extreme environments according to claim 1, characterized in that: In step (2), the insulation board is an XPS foam insulation board of 300×300×30 mm.

5. The method for testing the durability of assembled building sealants under extreme environments according to claim 1, characterized in that: The thermal conductivity meter of step (3) comprises a lifting device inside a box, two heat sinks, two temperature control systems, a hot plate, a cold plate, two temperature sensors, a cooling system and an external electronic data recording system; the sample structure to be tested is placed between the upper and lower temperature sensors, the upper temperature sensor is connected to the hot plate, the temperature control system and the heat sink in sequence, the lower temperature sensor is connected to the cold plate, the temperature control system and the heat sink in sequence, a lifting device is connected to each end of the upper heat sink, and the cooling system is connected to the upper and lower heat sinks.

6. The method for testing the durability of assembled building sealant under extreme environment according to claim 1, characterized in that: In step (4), the tensile adhesion test is performed on the specimen after 0, 5, 10, 15, 20, 25, 30 and 35 cycles respectively.

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