High-strength concrete antifreeze agent suitable for plateau environment

Abstract

The invention discloses a high-strength concrete antifreeze agent suitable for a plateau environment. The antifreeze agent is prepared from calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalene sulfonate, polyisocyanurate, alkynediol 104E and L methionine. The novel concrete antifreeze agent prepared by the invention is mixed with a natural sand-gravel material, a standard curing mode is adopted for forming, the maximum freezing and thawing cycle index of the prepared concrete can reach 450 times in 28d, and the concrete antifreeze agent has a great application prospect in the aspect of improving the antifreeze performance of the concrete in a plateau environment.

Description

Technical Field

[0001] The present invention is a new type of antifreeze agent for use in the plateau environment, belonging to the technical field of new building materials. The application of this antifreeze agent can greatly improve the frost resistance of concrete materials in the plateau construction process and ensure the smooth implementation of the construction process. Background Art

[0002] Plateau areas usually have harsh climate conditions such as low temperature, large temperature difference between day and night, dry and windy climate. In winter, frequent freeze-thaw cycles occur. When the water in concrete freezes at low temperature, its volume will expand by about 9%, generating huge internal stresses. As the number of freeze-thaw cycles increases, the internal stresses accumulate continuously, resulting in the generation of micro-cracks inside the concrete. These micro-cracks will gradually expand and connect, damaging the concrete structure, affecting the concrete performance, and ultimately seriously affecting the safety and service life of the concrete structure.

[0003] At present, certain research results have been achieved in the field of freeze-thaw resistant concrete. Traditional freeze-thaw resistant measures mainly reduce the freezing point of water in concrete by adding antifreeze agents to inhibit the growth of ice crystals, thereby reducing freeze-thaw damage. Common antifreeze agents include chloride salts, nitrites, etc. However, these traditional antifreeze agents have many problems.

[0004] On the one hand, although chloride salt antifreeze agents have a good effect of reducing the freezing point, chloride ions will cause serious corrosion to the steel bars in concrete, resulting in steel bar corrosion, and then affecting the overall performance of the concrete structure. On the other hand, the antifreeze effect of nitrite antifreeze agents is not ideal in the long-term freeze-thaw cycle process and is difficult to meet the frequent and high-intensity freeze-thaw requirements in the plateau environment.

[0005] In addition, although some new types of antifreeze agents pay attention to environmental protection and antifreeze performance during the research and development process, they ignore the special climate conditions and geological conditions in the plateau. For example, the low-pressure environment in the plateau area will affect the dispersibility and stability of the antifreeze agent in concrete, and some antifreeze agents do not fully consider this factor during the design, resulting in the inability of the antifreeze agent to be evenly distributed in the concrete during actual use and unable to effectively play its antifreeze and thawing resistance role. At the same time, the strong ultraviolet radiation in the plateau area may also damage the chemical structure of the antifreeze agent and reduce its antifreeze performance, but the performance of existing antifreeze agents in terms of anti-ultraviolet needs to be improved.

[0006] In summary, the existing freeze-thaw resistant technologies and antifreeze agents have not been able to fully meet the actual requirements for the long-term stable operation of concrete structures in the plateau environment, and there is an urgent need to develop a new type of antifreeze agent suitable for the plateau environment to solve these problems. Summary of the Invention

[0007] The present invention provides a method for preparing an antifreeze agent suitable for plateau environments, characterized in that:

[0008] 1. It consists of calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E, and L-methionine, and their mass percentages are respectively:

[0009] (1) The mass percentage of calcium nitrite: 7% - 11%;

[0010] (2) The mass percentage of alunite powder: 6% - 10%;

[0011] (3) The mass percentage of ethylene glycol: 21% - 34%;

[0012] (4) The mass percentage of glycerol: 1% - 5%;

[0013] (5) The mass percentage of polynaphthalenesulfonate: 0.5% - 2%;

[0014] (6) The mass percentage of polyisocyanurate: 0.5% - 1.5%;

[0015] (7) The mass percentage of alkynediol 104E: 1% - 2%;

[0016] (8) The mass percentage of L-methionine: 1% - 3%;

[0017] Among them, the balance is deionized water.

[0018] 2. The preparation method of the antifreeze agent is as follows:

[0019] (1) Weighing: Accurately weigh each component according to the mass ratio of each component.

[0020] (2) Using a ball mill to finely grind alunite powder and calcium nitrite. First, perform pre-crushing and screening. The rotation speed of the ball mill is between 50 - 70 revolutions per minute, and the diameter of the grinding balls can be selected as 15 mm.

[0021] (3) According to the calculated amount, first add calcium nitrite to the mixing equipment. Since calcium nitrite is in powder form, adding it can avoid dust flying. Then add the crushed alunite powder and let it evenly distribute on the calcium nitrite. Next, add the pre-mixed liquid components (ethylene glycol and glycerol). The addition of the liquid can help moisten the solid particles and promote mixing. When mixing calcium nitrite and the liquid components, use a stirring speed from low to high. In the first half hour, use a speed of 300 revolutions per minute, and after half an hour, increase it to 900 revolutions per minute. Then add polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E, and L-methionine in sequence, and reduce the stirring speed to 400 revolutions per minute. The total stirring time is 3 hours.

[0022] 3. When configuring concrete, the dosage of the antifreeze is 5%-6% of the mass of cement.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The molecular structure of polyisocyanurate has a relatively high closed-cell rate. Gas is difficult to flow in these closed cavities, which can play a good heat insulation role and has good tolerance to many chemical substances. In the complex chemical environment of the antifreeze, it may come into contact with other concrete admixtures, which can increase the viscosity and toughness of the antifreeze.

[0025] (2) Propargyl alcohol 104E can not only help form bubbles but also play a role in stabilizing bubbles. By stabilizing the bubbles, the bubbles can exist in the system for a long time, so as to better play the role of the air-entraining agent. This can ensure that the antifreeze can circulate efficiently in the system and maintain stable cooling and antifreeze functions.

[0026] (3) L-methionine is a sulfur-containing amino acid, which can act as a free radical scavenger. It can be combined with traditional antifreeze components such as ethylene glycol and propylene glycol, and can form a protective film on the metal surface to block the direct contact between salt ions and the metal. Detailed implementation method

[0027] To further demonstrate the effects brought by the present invention, the present invention will be further described in detail below in combination with specific application cases.

[0028] Example 1

[0029] 1. It is composed of calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalene sulfonate, polyisocyanurate, propargyl alcohol 104E, and L-methionine, and their mass percentages are respectively:

[0030] (1) The mass percentage of calcium nitrite: 7%;

[0031] (2) The mass percentage of alunite powder: 6%;

[0032] (3) The mass percentage of ethylene glycol: 21%;

[0033] (4) The mass percentage of glycerol: 3%;

[0034] (5) The mass percentage of polynaphthalene sulfonate: 1%;

[0035] (6) The mass percentage of polyisocyanurate: 0.8%;

[0036] (7) The mass percentage of propargyl alcohol 104E: 1%;

[0037] (8) The mass percentage of L-methionine: 3%;

[0038] Among them, the surplus is deionized water.

[0039] 2. The preparation method of the antifreeze is as follows:

[0040] (1) Weighing: Accurately weigh each component according to the mass ratio of each component.

[0041] (2) Use a ball mill to pre-crush and screen alunite powder and calcium nitrite. The rotation speed of the ball mill is between 70 revolutions per minute, and the diameter of the grinding balls is selected to be 15 mm.

[0042] (3) According to the calculated amount, first add calcium nitrite to the mixing equipment. Since calcium nitrite is in powder form, adding it can avoid dust flying. Then add the crushed alunite powder and let it evenly distribute on the calcium nitrite. Next, add the pre-mixed liquid components (ethylene glycol and glycerol). The addition of the liquid can help moisten the solid particles and promote mixing. When mixing calcium nitrite and the liquid components, use a stirring speed from low to high. For the first half hour, use 300 revolutions per minute, and after half an hour, increase it to 900 revolutions per minute. Then add polynaphthalenesulfonate, polyisocyanurate, acetylenic diol 104E, and L-methionine in sequence, and reduce the stirring speed to 400 revolutions per minute. The total stirring time is 3 hours.

[0043] 3. When configuring concrete, the dosage of the antifreeze is 6% of the mass of the cement.

[0044] According to JC 475-2004 "Concrete Antifreeze", test the usage of concrete specimens under different temperature conditions after freeze-thaw cycles under plateau construction conditions, and test the compressive and shear strengths of the concrete according to GB / T50476-2019 "Standard for Durability Design of Concrete Structures".

[0045] Example 2

[0046] 1. It is composed of calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalenesulfonate, polyisocyanurate, acetylenic diol 104E, and L-methionine, and their mass percentages are respectively:

[0047] (1) The mass percentage of calcium nitrite: 10%;

[0048] (2) The mass percentage of alunite powder: 7%;

[0049] (3) The mass percentage of ethylene glycol: 30%;

[0050] (4) The mass percentage of glycerol: 2%;

[0051] (5) The mass percentage of polynaphthalenesulfonate: 2%;

[0052] (6) Mass percentage of polyisocyanurate: 1%;

[0053] (7) Mass percentage of alkynediol 104E: 1.5%;

[0054] (8) Mass percentage of L-methionine: 2.5%;

[0055] Among them, the balance is deionized water.

[0056] 2. The preparation method of the antifreeze is as follows:

[0057] (1) Weighing: Accurately weigh each component according to the mass ratio of each component.

[0058] (2) Use a ball mill to pre-crush and screen alunite powder and calcium nitrite. The rotation speed of the ball mill is between 70 revolutions per minute, and the diameter of the grinding balls is selected as 15 mm.

[0059] (3) According to the calculated amount, first add calcium nitrite to the mixing equipment. Since calcium nitrite is in powder form, adding it can avoid dust flying. Then add the crushed alunite powder and let it be evenly distributed on the calcium nitrite. Then add the pre-mixed liquid components (ethylene glycol and glycerol). The addition of the liquid can help moisten the solid particles and promote mixing. When mixing calcium nitrite and the liquid components, use a stirring speed from low to high. The first half hour is at 300 revolutions per minute, and after half an hour, it is increased to 900 revolutions per minute. Then add polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E and L-methionine in turn, and reduce the stirring speed to 400 revolutions per minute. The total stirring time is 3 hours.

[0060] 3. When preparing concrete, the dosage of the antifreeze is 5% of the mass of cement.

[0061] According to JC 475-2004 "Concrete Antifreeze", test the usage of concrete specimens under different temperature conditions after freeze-thaw cycles under plateau construction conditions, and test the compressive and shear strengths of concrete according to GB / T50476-2019 "Standard for Durability Design of Concrete Structures".

[0062] Example 3

[0063] 1. It is composed of calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E, L-methionine, and their mass percentages are respectively:

[0064] (1) Mass percentage of calcium nitrite: 9%;

[0065] (2) Mass percentage of alunite powder: 8%;

[0066] (3) Mass percentage of ethylene glycol: 34%;

[0067] (4) Mass percentage of glycerol: 1%;

[0068] (5) Mass percentage of polynaphthalenesulfonate: 1.5%;

[0069] (6) Mass percentage of polyisocyanurate: 1.5%;

[0070] (7) Mass percentage of alkynediol 104E: 2%;

[0071] (8) Mass percentage of L-methionine: 2%;

[0072] Among them, the balance is deionized water.

[0073] 2. The preparation method of the antifreeze is as follows:

[0074] (1) Weighing: Accurately weigh each component according to the mass ratio of each component.

[0075] (2) Use a ball mill to pre-crush and screen alunite powder and calcium nitrite. The rotation speed of the ball mill is between 70 revolutions per minute, and the diameter of the grinding balls is selected as 15 mm.

[0076] (3) According to the calculated amount, first add calcium nitrite to the mixing equipment. Since calcium nitrite is in powder form, adding it can avoid dust flying. Then add the crushed alunite powder and let it be evenly distributed on the calcium nitrite. Then add the pre-mixed liquid components (ethylene glycol and glycerol). The addition of the liquid can help moisten the solid particles and promote mixing. When mixing calcium nitrite and the liquid components, use a stirring speed from low to high. The first half hour uses 300 revolutions per minute, and after half an hour, it is increased to 900 revolutions per minute. Then add polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E and L-methionine in turn, and reduce the stirring speed to 400 revolutions per minute. The total stirring time is 3 hours.

[0077] 3. When configuring concrete, the dosage of the antifreeze is 6% of the mass of cement.

[0078] According to JC 475-2004 "Concrete Antifreeze", test the usage of concrete specimens under different temperature conditions after freeze-thaw cycles under plateau construction conditions, and test the compressive and shear strengths of concrete according to GB / T50476-2019 "Standard for Durability Design of Concrete Structures".

[0079] Example 4

[0080] 1. It is composed of calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E, and L-methionine, and their mass percentages are respectively:

[0081] (1) Mass percentage of calcium nitrite: 11%;

[0082] (2) Mass percentage of alunite powder: 10%;

[0083] (3) Mass percentage of ethylene glycol: 34%;

[0084] (4) Mass percentage of glycerol: 5%;

[0085] (4) Mass percentage of polynaphthalenesulfonate: 2%;

[0086] (5) Mass percentage of polyisocyanurate: 1.5%;

[0087] (6) Mass percentage of alkynediol 104E: 1%;

[0088] (7) Mass percentage of L-methionine: 2%;

[0089] Among them, the balance is deionized water.

[0090] 2. The preparation method of the antifreeze is as follows:

[0091] (1) Weighing materials: Weigh each component accurately according to the mass ratio of each component.

[0092] (2) Use a ball mill to pre-crush and screen the alunite powder and calcium nitrite. The rotation speed of the ball mill is between 70 revolutions per minute, and the diameter of the grinding balls is selected as 15 mm.

[0093] (3) According to the calculated amount, first add calcium nitrite to the mixing equipment. Since calcium nitrite is in powder form, adding it can avoid dust flying. Then add the crushed alunite powder and let it be evenly distributed on the calcium nitrite. Next, add the pre-mixed liquid components (ethylene glycol and glycerol). The addition of the liquid can help moisten the solid particles and promote mixing. When mixing calcium nitrite and the liquid components, use a stirring speed from low to high. The first half hour is at 300 revolutions per minute, and after half an hour, it is increased to 900 revolutions per minute. Then add polynaphthalenesulfonate, polyisocyanurate, alkynediol 104E and L-methionine in turn, and reduce the stirring speed to 400 revolutions per minute. The total stirring time is 3 hours.

[0094] 3. When configuring concrete, the dosage of the antifreeze is 6% of the mass of cement.

[0095] According to JC 475-2004 "Concrete Antifreeze", test the usage of concrete specimens under different temperature conditions after freeze-thaw cycles under plateau construction conditions, and test the compressive and shear strengths of concrete according to GB / T50476-2019 "Standard for Durability Design of Concrete Structures".

[0096] Test results

[0097] In Examples 1 to 4, a control group was set up respectively. The composition ratio, forming, curing and test methods of the control group were the same as those of the examples. After the specimens with an age of 28 days were saturated with water absorption, they were subjected to repeated freeze-thaw cycles. The maximum number of freeze-thaw cycles that could be tolerated was 450 times when the compressive strength decreased by no more than 25% and the mass loss did not exceed 5%. The antifreeze used in the control group was CA-100R composite antifreeze. The test results of the control group and the examples are shown in Table 1.

[0098] Table 1 Results of relevant performance test indexes of comparative examples and examples

[0099] Group number Control group 1 Example 1 Example 2 Example 3 Example 4 Compressive strength (MPa) 145 156 150 153 160 Relative durability index / % 210 250 230 250 275 Air content / % 5.2 4.8 4.9 4.5 4.2 Water reduction rate / % 35 28 30 25 22 Mass loss rate / % 5.3 4.8 4.4 4.7 4.2

[0100] As can be seen from Table 1 above, the present invention innovatively uses a combination of three materials, namely polyisocyanurate, alkynediol 104E, and L-methionine, and conventional antifreeze materials. The working performance of the concrete prepared with the antifreeze of Examples 1-4 is significantly better than that of the control group. And the working state of Examples 1-4 in the plateau environment is better than that of ordinary antifreeze. It shows that the preparation method of an antifreeze applicable to the plateau environment provided by the present invention can well improve the working performance of concrete during construction in the plateau area, and can also improve the strength of concrete, and has high popularization and practical value.

Claims

1. An antifreeze agent applicable to plateau environments, characterized in that: it at least includes calcium nitrite, alunite powder, ethylene glycol, glycerol, polynaphthalene sulfonate, polyisocyanurate, alkynediol 104E, and L-methionine, and their mass percentages are respectively: (1) The mass percentage of calcium nitrite: 7% - 11%; (2) The mass percentage of alunite powder: 6% - 10%; (3) The mass percentage of ethylene glycol: 21% - 34%; (4) The mass percentage of glycerol: 1% - 5%; (5) The mass percentage of polynaphthalene sulfonate: 0.5% - 2%; (6) The mass percentage of polyisocyanurate: 0.5% - 1.5%; (7) The mass percentage of alkynediol 104E: 1% - 2%; (8) The mass percentage of L-methionine: 1% - 3%; wherein, the balance is deionized water.

2. A method for preparing the antifreeze agent as claimed in claim 1, characterized in that: (1) Weighing materials: Weigh each component according to the mass ratio of each component; (2) Using a ball mill to ball mill alunite powder and calcium nitrite; (3) According to the calculated amount, first add calcium nitrite to the mixing equipment; then add the pulverized alunite powder and let it be evenly distributed on the calcium nitrite; then add the pre-mixed liquid components, namely ethylene glycol and glycerol; when calcium nitrite and the liquid components are mixed, use a stirring speed from low to high, 300 revolutions per minute in the first half hour, and increase to 900 revolutions per minute after half an hour; then add polynaphthalene sulfonate, polyisocyanurate, alkynediol 104E and L-methionine, reduce the stirring speed and adjust it to 400 revolutions per minute; the total stirring time is 3 hours.

3. The application of the antifreeze agent as claimed in claim 1. When configuring concrete, the dosage of the antifreeze agent is 5% - 6% of the mass of cement.