Test method for rapidly measuring gas content of concrete mixture on construction site

Abstract

The invention discloses a test method for rapidly measuring the gas content of a concrete mixture on a construction site. The test method comprises the following steps: S1, weighing a plurality of parts of concrete preparation materials; s2, the preparation materials are added into a stirrer to be stirred, and concrete is obtained; s3, measuring the air content of a mixture of the concrete, and weighing the volume weight of the concrete; s4, a plurality of parts of concrete preparation materials and an air entraining agent are taken and added into a concrete mixer to be stirred, and a plurality of parts of concrete are obtained; s5, measuring the air content and volume weight of a mixture of a plurality of parts of concrete; s6, calculating a gas content change value and a volume weight change value; s7, drawing a standard curve according to the plurality of mixture gas content change values and volume weight change values, and obtaining a regression equation; and S8, weighing the volume weight of on-site concrete, and calculating the air content of the on-site measured concrete mixture. According to the test method for rapidly measuring the gas content of the concrete mixture on the construction site, the measuring efficiency of the gas content of the concrete on the site is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete parameter determination, and in particular relates to a test method for rapidly determining the air content of concrete mixtures at a construction site. Background Art

[0002] Hydraulic concrete is affected by complex environmental conditions, especially seasonal temperature changes. The concrete surface is prone to peeling and falling off, and even the entire concrete is damaged, affecting the normal service life of hydraulic structures. Introducing an appropriate amount of closed micro-bubbles into concrete can effectively improve its anti-freeze performance. However, due to various factors, the air content is prone to large fluctuations during on-site concrete construction. Therefore, air content detection is an important indicator to ensure the durability of concrete. However, the existing concrete gas content is usually measured by volume method using a concrete air content meter. This method has the following defects: (1) The volumetric method requires pure water, which is inconvenient to carry when testing at the construction site. After the test, the water is contaminated and cannot be reused, resulting in a waste of water resources.

[0003] (2) When the work of measuring air content is small, the volume method is relatively simple. However, when the concrete pouring volume is large and the pouring time is long, and the air content needs to be tested and controlled many times, the volume method will take a lot of time and manpower and is not efficient. Summary of the invention

[0004] The invention aims to provide a test method for quickly determining the air content of concrete mixtures at a construction site, thereby improving the efficiency of determining the air content of concrete at the site.

[0005] The technical solution adopted by the present invention is a test method for rapidly determining the air content of concrete mixture at a construction site, comprising the following steps: S1. Weigh multiple portions of concrete preparation materials; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; S5. Determine the air content of several concrete mixtures An and bulk density c n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; S8. Take concrete samples on site, weigh the bulk density, obtain the difference in air content of the concrete mixture based on the regression equation, and calculate the air content of the concrete mixture tested on site.

[0006] The present invention is also characterized in that: The materials for preparing concrete in S1 include coarse aggregate, fine aggregate, cementitious material, water and water reducing agent.

[0007] The ratio of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent in S2 is: the ratio of the volume of cementitious material added to the volume of water added is 1:(0.5-0.3), the ratio of the volume of water added to the volume of fine aggregate added is (0.5-0.3):(1.79-3.98), the ratio of the volume of fine aggregate added to the volume of coarse aggregate added is (1.79-3.98):(2.85-5.76), and the ratio of the volume of coarse aggregate added to the volume of water reducing agent added is (2.85-5.76):(0.008-0.014).

[0008] The concrete mixer in S2 adopts a forced mixer, the speed of the concrete mixer is 45-48r / min, the mixing time is 2-3min, and the mixing temperature is 15-25℃.

[0009] The volume of air entraining agent added in S4 is 0.05%-0.30% of the volume of cementitious material added.

[0010] The specific process of S5 is: using the air content measuring instrument to measure the concrete C 1, C 2, ..., C n Air content of the mixture A 1, A 2, ..., A n , use a volumetric cylinder to weigh out concrete C 1, C 2, ..., C n Bulk density c 1, c 2, ..., c n .

[0011] The process of calculating the change values ​​of the air content of several concrete mixtures in S6 is as follows: Calculate the change value of the air content of each concrete mixture according to formula (1): △A : △A = A m - A 0 (1); in, A m is the air content of concrete mixture with air-entraining agent, %, m ∈(0,n]; A 0 is the air content of concrete mixture without air entraining agent, %.

[0012] The calculation process of the concrete density change value in S6 is as follows: Calculate the concrete density change value according to formula (2): △ c : △γ = c 0- c m (2); in, c 0 is the concrete density without air entraining agent, unit: kg / m 3 ; c m The unit weight of concrete with air-entraining agent is kg / m 3 , m ∈(0,n].

[0013] The specific process of S7 is: using the change value of each concrete bulk density as the horizontal coordinate and the change value of each concrete mixture air content as the vertical coordinate, a standard curve of the change value of air content and the change value of bulk density is drawn, and a linear regression is performed on the standard curve to obtain a regression equation of the change value of air content and the change value of bulk density.

[0014] The specific process of S8 is: S8.1. Obtain the difference in air content of concrete mixture according to the regression equation. The regression equation is: A 检 =kγ+b (3); S8.2 Calculate the air content of the concrete mixture according to formula (4): A=A 检 + A 0 (4); in, A 检 is the difference in air content of concrete mixture, %; k is the regression coefficient, a constant;b is the intercept on the standard curve, a constant; A is the air content of the concrete mixture being tested, %; A 0 is the air content of concrete mixture without air entraining agent, %.

[0015] The beneficial effects of the present invention are: The invention provides a method for quickly determining the gas content of concrete mixtures at a construction site, which does not require carrying a gas content determination instrument or pure water, and can simply, quickly and accurately detect the gas content of concrete, and is highly practical. The invention is simple to operate, and can be quickly mastered by non-professional test personnel, which greatly reduces the workload of on-site test personnel. In particular, when the detection workload is large, the method can replace the gas content determination instrument method to complete the determination, greatly reducing the determination time and efficiently completing the determination task. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with specific implementation modes.

[0017] Example 1 The test method for rapidly determining the air content of concrete mixture at a construction site proposed in this embodiment comprises the following steps: S1. Weigh multiple portions of concrete preparation materials; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; S5. Determine the air content of several concrete mixtures A n and bulk density c n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; S8. Take concrete samples on site, weigh the bulk density, obtain the difference in air content of the concrete mixture based on the regression equation, and calculate the air content of the concrete mixture tested on site.

[0018] Example 2 The test method for rapidly determining the air content of concrete mixture at a construction site proposed in this embodiment comprises the following steps: S1. Weigh multiple portions of concrete preparation materials; Materials for preparing concrete include coarse aggregate, fine aggregate, cementitious materials, water and water reducing agent; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; The proportions of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent are as follows: the volume ratio of cementitious material added to the volume of water added is 1: (0.5-0.3), the volume ratio of water added to the volume of fine aggregate added is (0.5-0.3): (1.79-3.98), the volume ratio of fine aggregate added to the volume of coarse aggregate added is (1.79-3.98): (2.85-5.76), the volume ratio of coarse aggregate added to the volume of water reducing agent added is (2.85-5.76): (0.008-0.014); The concrete mixer adopts a forced mixer, the speed of the concrete mixer is 45-48r / min, the mixing time is 2-3min, and the mixing temperature is 15-25℃; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; S5. Determine the air content of several concrete mixtures A n and bulk density c n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; S8. Take concrete samples on site, weigh the bulk density, obtain the difference in air content of the concrete mixture based on the regression equation, and calculate the air content of the concrete mixture tested on site.

[0019] Example 3 The test method for rapidly determining the air content of concrete mixture at a construction site proposed in this embodiment comprises the following steps: S1. Weigh multiple portions of concrete preparation materials; Materials for preparing concrete include coarse aggregate, fine aggregate, cementitious materials, water and water reducing agent; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; The proportions of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent are as follows: the volume ratio of cementitious material added to the volume of water added is 1: (0.5-0.3), the volume ratio of water added to the volume of fine aggregate added is (0.5-0.3): (1.79-3.98), the volume ratio of fine aggregate added to the volume of coarse aggregate added is (1.79-3.98): (2.85-5.76), the volume ratio of coarse aggregate added to the volume of water reducing agent added is (2.85-5.76): (0.008-0.014); The concrete mixer adopts a forced mixer, the speed of the concrete mixer is 45-48r / min, the mixing time is 2-3min, and the mixing temperature is 15-25℃; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; The volume of air entraining agent added is 0.05%-0.30% of the volume of cementitious material added; S5. Determine the air content of several concrete mixtures A n and bulk density c n ; The specific process is: using the air content meter to measure the concrete C 1, C 2, ..., C n Air content of the mixture A 1,A 2, ..., A n , use a volumetric cylinder to weigh out the concrete C 1, C 2, ..., C n Bulk density c 1, c 2, ..., c n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; S8. Take concrete samples on site, weigh the bulk density, obtain the difference in air content of the concrete mixture based on the regression equation, and calculate the air content of the concrete mixture tested on site.

[0020] Example 4 The test method for rapidly determining the air content of concrete mixture at a construction site proposed in this embodiment comprises the following steps: S1. Weigh multiple portions of concrete preparation materials; Materials for preparing concrete include coarse aggregate, fine aggregate, cementitious materials, water and water reducing agent; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; The proportions of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent are as follows: the volume ratio of cementitious material added to the volume of water added is 1: (0.5-0.3), the volume ratio of water added to the volume of fine aggregate added is (0.5-0.3): (1.79-3.98), the volume ratio of fine aggregate added to the volume of coarse aggregate added is (1.79-3.98): (2.85-5.76), the volume ratio of coarse aggregate added to the volume of water reducing agent added is (2.85-5.76): (0.008-0.014); The concrete mixer adopts a forced mixer, the speed of the concrete mixer is 45-48r / min, the mixing time is 2-3min, and the mixing temperature is 15-25℃; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; The volume of air entraining agent added is 0.05%-0.30% of the volume of cementitious material added; S5. Determine the air content of several concrete mixtures A n and bulk density c n ; The specific process is: using the air content meter to measure the concrete C 1, C 2, ..., C n Air content of the mixture A 1, A 2, ..., A n , use a volumetric cylinder to weigh out the concrete C 1, C 2, ..., C n Bulk density c 1, c 2, ..., c n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; The process of calculating the change value of the air content of several concrete mixtures is as follows: Calculate the change value of the air content of each concrete mixture according to formula (1): △A : △A = A m - A 0 (1); in, A m is the air content of concrete mixture with air-entraining agent, %, m ∈(0,n]; A 0 is the air content of concrete mixture without air entraining agent, %; The calculation process of the concrete bulk density change value is as follows: Calculate the concrete bulk density change value according to formula (2): △γ : △γ = c 0- c m (2); in, c 0 is the concrete density without air entraining agent, unit: kg / m 3 ; c m The unit weight of concrete with air-entraining agent is kg / m 3 , m ∈(0,n]; S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; S8. Take concrete samples on site, weigh the bulk density, obtain the difference in air content of the concrete mixture based on the regression equation, and calculate the air content of the concrete mixture tested on site.

[0021] Example 5 The test method for rapidly determining the air content of concrete mixture at a construction site proposed in this embodiment comprises the following steps: S1. Weigh multiple portions of concrete preparation materials; Materials for preparing concrete include coarse aggregate, fine aggregate, cementitious materials, water and water reducing agent; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; The proportions of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent are as follows: the volume ratio of cementitious material added to the volume of water added is 1: (0.5-0.3), the volume ratio of water added to the volume of fine aggregate added is (0.5-0.3): (1.79-3.98), the volume ratio of fine aggregate added to the volume of coarse aggregate added is (1.79-3.98): (2.85-5.76), the volume ratio of coarse aggregate added to the volume of water reducing agent added is (2.85-5.76): (0.008-0.014); The concrete mixer adopts a forced mixer, the speed of the concrete mixer is 45-48r / min, the mixing time is 2-3min, and the mixing temperature is 15-25℃; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; The volume of air entraining agent added is 0.05%-0.30% of the volume of cementitious material added; S5. Determine the air content of several concrete mixtures A n and bulk density c n ; The specific process is: using the air content meter to measure the concrete C 1, C 2, ..., C n Air content of the mixture A 1, A 2, ..., A n , use a volumetric cylinder to weigh out the concrete C 1, C 2, ..., C n Bulk density c 1, c 2, ..., c n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; The process of calculating the change value of the air content of several concrete mixtures is as follows: Calculate the change value of the air content of each concrete mixture according to formula (1): △A : △A = A m - A 0 (1); in, A m is the air content of concrete mixture with air-entraining agent, %, m ∈(0,n]; A 0 is the air content of concrete mixture without air entraining agent, %; The calculation process of the concrete bulk density change value is as follows: Calculate the concrete bulk density change value according to formula (2): △γ : △γ = c 0- c m (2); in, c 0 is the concrete density without air entraining agent, unit: kg / m 3 ; c m The unit weight of concrete with air-entraining agent is kg / m 3 , m ∈(0,n]; S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; The specific process is as follows: with the change value of each concrete bulk density as the horizontal coordinate and the change value of each concrete mixture air content as the vertical coordinate, a standard curve of the change value of air content and the change value of bulk density is drawn, and a linear regression is performed on the standard curve to obtain a regression equation of the change value of air content and the change value of bulk density; S8. Take a concrete sample on site, weigh the bulk density, obtain the difference in air content of the concrete mixture according to the regression equation, and calculate the air content of the concrete mixture tested on site; The specific process of S8 is: S8.1. Obtain the difference in air content of concrete mixture according to the regression equation. The regression equation is: A 检 =kγ+b (3); S8.2 Calculate the air content of the concrete mixture according to formula (4): A=A 检 + A 0 (4); in, A 检 is the difference in air content of concrete mixture, %; k is the regression coefficient, a constant; b is the intercept on the standard curve, a constant; A is the air content of the concrete mixture being tested, %; A 0 is the air content of concrete mixture without air entraining agent, %.

[0022] Example 6 The test method for rapidly determining the air content of concrete mixture at a construction site proposed in this embodiment comprises the following steps: S1. Weigh 6 parts of concrete preparation materials; Materials for preparing concrete include coarse aggregate, fine aggregate, cementitious materials, water and water reducing agent; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; The proportions of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent are as follows: the volume ratio of cementitious material added to the volume of water added is 1:0.4, the volume ratio of water added to the volume of fine aggregate added is 0.4:2.5, the volume ratio of fine aggregate added to the volume of coarse aggregate added is 2.5:4.0, and the volume ratio of coarse aggregate added to the volume of water reducing agent added is 4.0:0.01; The concrete mixer adopts a forced mixer, the speed of the concrete mixer is 46r / min, the mixing time is 2.5min, and the mixing temperature is 20℃; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density c 0; S4, take 5 parts of concrete preparation materials and air entraining agent, add them into concrete mixer and mix them to obtain 5 parts of concrete C 1, C 2, ..., C 5; The volume of air entraining agent added is 0.05%, 0.15%, 0.20%, 0.25% and 0.30% of the volume of cementitious material added respectively; S5. Determine the air content of 5 parts of concrete mixture A n and bulk density c n ; The specific process is: using the air content meter to measure the concrete C 1, C 2, ..., C 5% gas content of the mixture A 1, A 2, ..., A 5. Use a volumetric cylinder to weigh concrete C 1, C 2, ..., C 5 bulk density c 1, c 2, ..., c 5; S6. Calculate the change in air content of 5 parts of concrete mixture △A Changes in concrete density △γ ; The process of calculating the change value of air content of five concrete mixtures is as follows: Calculate the change value of air content of each concrete mixture according to formula (1): △A : △A = A m - A 0 (1); in, A m is the air content of concrete mixture with air-entraining agent, %, m ∈[0,5]; A 0 is the air content of concrete mixture without air entraining agent, %; The calculation process of the concrete bulk density change value is as follows: Calculate the concrete bulk density change value according to formula (2): △γ : △γ = c 0- c m (2); in, c 0 is the concrete density without air entraining agent, unit: kg / m 3 ; c m The concrete density of each air-entraining agent, unit: kg / m 3 , m ∈[0,5].

[0023] S7, drawing a standard curve according to a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtaining a regression equation; The specific process is as follows: with the change value of each concrete bulk density as the horizontal coordinate and the change value of each concrete mixture air content as the vertical coordinate, a standard curve of the change value of air content and the change value of bulk density is drawn, and a linear regression is performed on the standard curve to obtain a regression equation of the change value of air content and the change value of bulk density; S8. Take a concrete sample on site, weigh the bulk density, obtain the difference in air content of the concrete mixture according to the regression equation, and calculate the air content of the concrete mixture tested on site; The specific process is: S8.1. Obtain the difference in air content of concrete mixture according to the regression equation. The regression equation is: A 检 =kγ+b (3); S8.2 Calculate the air content of the concrete mixture according to formula (4): A=A 检 + A 0 (4); in, A 检 is the difference in air content of concrete mixture, %; k is the regression coefficient, a constant; b is the intercept on the standard curve, a constant; A is the air content of the concrete mixture being tested, %; A 0 is the air content of concrete mixture without air entraining agent, %; While testing according to the method of the present invention, the concrete air content is measured by a concrete air content measuring instrument using a volumetric method. The test results of the two methods are compared and shown in Table 1. Table 1 Comparison of results between the method of the present invention and the volumetric method

[0024] It can be seen that the air content of the concrete mixture at the construction site measured by the present invention is basically consistent with the air content of the mixture measured by the volume method, and the value measured by the present invention is accurate and reliable.

Claims

1. A test method for rapidly determining the air content of concrete mixtures at a construction site, characterized in that: The following steps are involved: S1. Weigh multiple portions of concrete preparation materials; S2. Add 1 part of concrete preparation material into a concrete mixer and mix to obtain concrete. C 0; S3. Use air content measuring instrument to measure concrete C 0 gas content of the mixture A 0. Use a volumetric cylinder to weigh out concrete C 0 bulk density γ 0; S4. Take several portions of concrete preparation materials and air entraining agent, add them into concrete mixers for mixing, and obtain several portions of concrete. C 1, C 2, ..., C n ; S5. Determine the air content of several concrete mixtures A n and bulk density γ n ; S6. Calculate the change in air content of several portions of concrete mixture △A Changes in concrete density △γ ; S7. Draw a standard curve based on a number of concrete mixture air content change values ​​and concrete bulk density change values, and obtain a regression equation; S8. Take concrete samples on site, weigh the bulk density, obtain the difference in air content of the concrete mixture based on the regression equation, and calculate the air content of the concrete mixture tested on site.

2. The method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The concrete preparation materials described in S1 include coarse aggregate, fine aggregate, cementitious material, water and water reducing agent.

3. The method for rapidly determining the air content of concrete mixtures at a construction site according to claim 2, characterized in that: The ratio of coarse aggregate, fine aggregate, cementitious material, water and water reducing agent described in S2 is: the ratio of the volume of cementitious material added to the volume of water added is 1:(0.5-0.3), the ratio of the volume of water added to the volume of fine aggregate added is (0.5-0.3):(1.79-3.98), the ratio of the volume of fine aggregate added to the volume of coarse aggregate added is (1.79-3.98):(2.85-5.76), and the ratio of the volume of coarse aggregate added to the volume of water reducing agent added is (2.85-5.76):(0.008-0.014).

4. The method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The concrete mixer in S2 is a forced mixer, the rotation speed of the concrete mixer is 45-48 r / min, the stirring time is 2-3 min, and the stirring temperature is 15-25°C.

5. The test method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The volume of the air entraining agent added in S4 is 0.05%-0.30% of the volume of the cementitious material added.

6. The test method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The specific process of S5 is: using an air content measuring instrument to measure the concrete C 1, C 2, ..., C n Air content of the mixture A 1, A 2, ..., A n , use a volumetric cylinder to weigh out concrete C 1, C 2, ..., C n Bulk density γ 1, γ 2, ..., γ n .

7. The test method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The process of calculating the air content change values ​​of several concrete mixtures in S6 is as follows: Calculate the air content change value of each concrete mixture according to formula (1): △A : △A = A m - A 0（1）； in, A m is the air content of concrete mixture with air-entraining agent, %, m ∈(0,n]; A 0 is the air content of concrete mixture without air entraining agent, %.

8. The test method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The calculation process of the concrete bulk density change value in S6 is as follows: Calculate the concrete bulk density change value according to formula (2): △ γ : △γ = γ 0- γ m （2）； in, γ 0 is the concrete density without air entraining agent, unit: kg / m 3 ; γ m The unit weight of concrete with air-entraining agent is kg / m 3 , m ∈(0,n].

9. The test method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The specific process of S7 is: using the change value of each concrete bulk density as the horizontal coordinate and the change value of each concrete mixture air content as the vertical coordinate, drawing a standard curve of the change value of air content and the change value of bulk density, performing linear regression on the standard curve, and obtaining a regression equation of the change value of air content and the change value of bulk density.

10. The test method for rapidly determining the air content of concrete mixtures at a construction site according to claim 1, characterized in that: The specific process of S8 is as follows: S8.

1. Obtain the difference in air content of the concrete mixture according to the regression equation, wherein the regression equation is: A 检 =kγ+b （3）； S8.2 Calculate the air content of the concrete mixture according to formula (4): A=A 检 + A 0（4）； in, A 检 is the difference in air content of concrete mixture, %; k is the regression coefficient, a constant; b is the intercept on the standard curve, a constant; A is the air content of the concrete mixture being tested, %; A 0 is the air content of concrete mixture without air entraining agent, %.

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