Cold-resistant and salt-resistant concrete admixture, preparation method and application thereof

Abstract

The application provides an anti-cold and anti-salt concrete admixture as well as a preparation method and application thereof, and belongs to the technical field of building and civil engineering.The concrete admixture comprises a water reducing agent, an antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano-montmorillonite and a coupling agent, wherein the antifreeze agent is diethylene glycol butyl ether acetate, hexaethylphosphorus triamide and copper 2-ethylhexanoate.Through the compounding use of the components, the compactness of the concrete is effectively improved, so that the concrete provided by the application has good anti-cold, anti-frozen, anti-permeability and anti-salt erosion properties, and the strength of the concrete can also be improved.

Description

Technical Field

[0001] This invention belongs to the field of building and civil engineering technology, specifically relating to a cold-resistant and salt-resistant concrete admixture, its preparation method, and its application. Background Technology

[0002] Concrete is one of the most widely used building materials, playing an irreplaceable role in the construction of roads, bridges, buildings, ports, docks, and dams. However, in practical applications, concrete is easily affected by climate conditions such as rain erosion, wind erosion, and freeze-thaw cycles. Furthermore, during service, concrete components often develop cracks due to load, increasing the entry of corrosive salts into the concrete's internal channels, leading to structural damage, reduced strength, decreased durability, and a significantly shortened service life. Adding admixtures to concrete is one of the most effective ways to improve its various properties and meet engineering durability requirements.

[0003] There are many types of concrete admixtures, each achieving different effects. For example, water-reducing agents and air-entraining agents can improve the rheological properties of concrete mixtures, while retarders, accelerators, and quick-setting agents can adjust the setting time and hardening properties of concrete. However, the choice of concrete additives and the method of addition can significantly affect the performance of concrete.

[0004] Chinese patent application 201310448932.8 discloses a concrete additive comprising a high-efficiency water-reducing agent, an organosilicon waterproofing agent, sodium β-naphthyl sulfonate formaldehyde condensate, sodium sulfate, triethanolamine, alkylbenzene sulfonate, ethylene glycol, glycerol, silicone, and water. This concrete additive has the effects of preventing water seepage and resisting impact, and can improve the strength and abrasion resistance of concrete.

[0005] Chinese patent application 202111401474.3 discloses a concrete admixture and its preparation method, comprising a water-reducing agent mother liquor, sodium alginate, lignosulfonate, potassium acrylate, polyethylene glycol, sodium silicate, first deionized water, and other additives; through the synergistic effect of the components, the bleeding rate of concrete can be significantly reduced, the workability, strength, and durability of concrete can be improved, and it also has good antifreeze, cold-resistant, and waterproof properties.

[0006] Although there are many concrete admixtures available on the market, they still have certain drawbacks in practical applications. For example, while they may have good water-reducing effects, they can increase bleeding rates, affecting concrete quality, compromising its resistance to salt corrosion and freeze-thaw cycles, and reducing its strength and abrasion resistance. Therefore, it is necessary to research new concrete admixtures. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a cold-resistant and salt-resistant concrete admixture, its preparation method, and its application. Through the interaction of its components, the admixture can significantly improve the cold-resistant and frost-resistant properties, salt-resistant properties, crack-resistant properties, and compressive strength of concrete, thus meeting the engineering durability requirements of concrete under low-temperature conditions.

[0008] The present invention achieves the above objectives through the following technical solutions:

[0009] On the one hand, a cold-resistant and salt-resistant concrete admixture includes a water-reducing agent, an antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano-montmorillonite, a coupling agent, and a blending agent; among which,

[0010] The antifreeze contains diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate.

[0011] Preferably, the cold-resistant and salt-resistant concrete admixture is composed of a water-reducing agent, an antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano-montmorillonite, a coupling agent, and a blending agent.

[0012] Furthermore, the cold-resistant and salt-resistant concrete admixture is composed of the following components by weight percentage: 30%-50% water-reducing agent, 30%-42% antifreeze agent, 5%-12% calcium carbonate, 5%-10% polyvinyl alcohol, 4%-8% nano montmorillonite, 0.5%-3% coupling agent, and the balance being a blending agent.

[0013] Furthermore, the cold-resistant and salt-resistant concrete admixture is composed of the following components by weight percentage: 38%-45% water-reducing agent, 32%-36% antifreeze agent, 6%-8% calcium carbonate, 5%-7% polyvinyl alcohol, 6%-7.5% nano montmorillonite, 1%-2% coupling agent, and the balance being a blending agent.

[0014] Preferably, the cold-resistant and salt-resistant concrete admixture is composed of the following components by weight percentage: 43% water-reducing agent, 33% antifreeze agent, 7.5% calcium carbonate, 6.8% polyvinyl alcohol, 7.2% nano-montmorillonite, 1.2% coupling agent, and the balance being a blending agent.

[0015] Further, the water-reducing agent is selected from at least one of polycarboxylate-based water-reducing agents, naphthalene-based water-reducing agents, melamine-based water-reducing agents, lignin sulfonate-based water-reducing agents, aminosulfonate-based water-reducing agents, and fatty acid-based water-reducing agents. Preferably, the water-reducing agent is selected from at least one of melamine-based water-reducing agents, sodium lignin sulfonate-based water-reducing agents, and sodium aminosulfonate-based water-reducing agents.

[0016] Furthermore, the mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 3-6:2-4:1-1.8.

[0017] Furthermore, the mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 4.2-5:3-3.4:1.2-1.4.

[0018] Preferably, the mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 4.6:3.3:1.3.

[0019] Furthermore, the molecular weight of the polyvinyl alcohol is 120,000 to 200,000, preferably 150,000 to 170,000.

[0020] Further, the coupling agent is selected from at least one of silane coupling agents, titanate coupling agents, or aluminate coupling agents; preferably, the coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, propyltriethoxysilane, triisostearoyl titanate isopropyl ester, and distearate isopropyl aluminate.

[0021] Furthermore, the preparation method of the modified nano-montmorillonite includes the following steps:

[0022] Nano-montmorillonite was pretreated with acid, then washed with water until neutral, and then added to a solvent. Polyethylene glycol diglycidyl ether and glycerol were added to carry out a modification reaction to obtain modified nano-montmorillonite.

[0023] Furthermore, in the preparation process of modified nano-montmorillonite, the acid solution is a mixed aqueous solution of acetic acid and citric acid; the mass fraction of acetic acid in the acid solution is 10%-20%, and the mass fraction of citric acid is 2%-5%; preferably, the mass fraction of acetic acid in the acid solution is 12%-15%, and the mass fraction of citric acid is 3%-4%.

[0024] Furthermore, in the preparation process of modified nano-montmorillonite, the mass ratio of nano-montmorillonite to acid is 1:10-20; preferably, the mass ratio is 1:10-15.

[0025] Furthermore, in the preparation process of modified nano-montmorillonite, the acid treatment temperature is 50-70℃ and the time is 10-60 min; preferably, the acid treatment temperature is 60-65℃ and the time is 30-45 min.

[0026] Furthermore, in the preparation process of modified nano-montmorillonite, the solvent is dimethylacetamide and / or dimethylformamide.

[0027] Furthermore, in the preparation process of modified nano-montmorillonite, the solvent is an organic solvent, and the mass ratio of the nano-montmorillonite to the organic solvent is 1:5-10; preferably, the mass ratio is 1:7-8.

[0028] Furthermore, in the preparation process of modified nano-montmorillonite, the amount of polyethylene glycol diglycidyl ether added is 10%-15% of the mass of the nano-montmorillonite; preferably, the amount of polyethylene glycol diglycidyl ether added is 12%-13.5% of the mass of the nano-montmorillonite.

[0029] Furthermore, in the preparation process of modified nano-montmorillonite, the amount of glycerol added is 1%-5% of the mass of the nano-montmorillonite; preferably, the amount of glycerol added is 2%-3% of the mass of the nano-montmorillonite.

[0030] Furthermore, in the preparation process of modified nano-montmorillonite, the modification reaction time is 0.5-2 h and the reaction temperature is 60-70 °C; preferably, the modification reaction time is 1-1.5 h and the reaction temperature is 65-70 °C.

[0031] Furthermore, the blending agent is selected from at least one of defoamers, air-entraining agents, and thickeners.

[0032] Furthermore, the defoamer is selected from at least one of polyethers, organosilicones, and polyether-modified silicone oils. The defoamer serves to eliminate air bubbles in the concrete flexibility agent, and is preferably at least one of polyoxypropylene glycerol ether, polyoxyethylene glycerol ether, polyoxypropylene ethylene oxide glycerol ether, and glycerol polyoxyethylene polyoxypropylene ether.

[0033] Furthermore, the air-entraining agent is selected from at least one of rosin resins, alkyl and alkyl aromatic sulfonates, and dodecyl sulfate saponins; preferably, at least one of sodium lignosulfonate, rosin soap, and sodium dodecyl sulfate.

[0034] Furthermore, the thickener is selected from at least one of hydroxypropyl methylcellulose ether, hydroxyethyl cellulose ether, polyvinyl alcohol, and polyacrylamide, and the thickener plays a role in water retention, thickening, and anti-sagging; preferably hydroxypropyl methylcellulose ether and / or hydroxyethyl cellulose ether.

[0035] On the other hand, the preparation method of the above-mentioned cold-resistant and salt-resistant concrete admixture includes the following steps:

[0036] (1) Modified nano-montmorillonite was uniformly dispersed in water to obtain mixture I;

[0037] (2) The water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol and water are mixed evenly to obtain mixture II;

[0038] (3) Mix the mixture I obtained in step (1), the mixture II obtained in step (2) and the admixture, microwave-assisted heating treatment, and drying to obtain cold-resistant and salt-resistant concrete admixture.

[0039] Further, in step (3), the microwave power of the microwave-assisted heating treatment is 300-600W, the heating temperature is 45-60℃, and the time is 5-40min; preferably, the microwave power is 400-500W, the heating temperature is 50-55℃, and the time is 10-25min.

[0040] Preferably, in step (3), a modifier is added before the microwave-assisted heating treatment.

[0041] On the other hand, the above-mentioned cold-resistant and salt-resistant concrete admixtures are used in cold-resistant and salt-resistant concrete.

[0042] Furthermore, the mass fraction of the cold-resistant and salt-resistant concrete admixture added to the cold-resistant and salt-resistant concrete is 0.05%-5%.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The present invention effectively improves the density of concrete by using water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano montmorillonite and blending agent in combination, so that the concrete provided by the present invention has good cold resistance, frost resistance, impermeability and salt erosion resistance, and can also improve the strength of concrete.

[0045] (2) The present invention uses diethylene glycol butyl ether acetate, hexaethylphosphoric triamine and copper 2-ethylhexanoate as antifreeze agents. Through the synergistic effect of the three, the cold resistance and frost resistance of concrete can be significantly improved. Further optimization of the dosage ratio of the three can not only improve the cold resistance and frost resistance of concrete, but also further improve the dispersibility of admixtures on concrete particles, further enhance the performance of concrete after the admixtures are added, thereby improving the strength and salt erosion resistance of concrete.

[0046] (3) The concrete admixture of the present invention adds modified nano-montmorillonite. Compared with nano-montmorillonite, the addition of modified nano-montmorillonite can not only promote the hydration reaction of cement, fill the micropores inside the concrete to make the concrete denser, further improve the crack resistance and salt erosion resistance of the concrete, but also improve the strength of the concrete.

[0047] (4) In the process of preparing concrete admixtures, the present invention utilizes microwave-assisted heating treatment, which helps to disperse the concrete admixtures evenly, thereby giving full play to the role of each component and improving the overall performance of concrete. Detailed Implementation

[0048] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0049] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0050] Example 1

[0051] The cold-resistant and salt-resistant concrete admixture, by weight percentage, is made of 43% water-reducing agent, 33% antifreeze agent, 7.5% calcium carbonate, 6.8% polyvinyl alcohol (molecular weight 150,000), 6.8% modified nano-montmorillonite, 1.2% propyltriethoxysilane 3-isocyanate, and the balance being a blending agent.

[0052] The mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 4.6:3.3:1.3.

[0053] The water-reducing agent is sodium aminosulfonate.

[0054] The blending agent comprises polyoxypropylene ethylene glycerol ether defoamer, sodium dodecyl sulfate air-entraining agent, and hydroxyethyl cellulose ether thickener in a mass ratio of 1:1:1.

[0055] The modified nano-montmorillonite was prepared by the following method:

[0056] One part by weight of nano-montmorillonite was added to 10 parts by weight of an aqueous solution containing 14% acetic acid and 4% citric acid by mass. The solution was treated at 65°C for 40 min. After removal, the solution was washed with water until neutral. Then, it was added to 8 parts by weight of dimethylacetamide, along with 0.13 parts by weight of polyethylene glycol diglycidyl ether and 0.06 parts by weight of glycerol. The solution was reacted at 70°C for 1 h. After the reaction was completed, the solution was removed and dried to obtain modified nano-montmorillonite.

[0057] This embodiment also provides a method for preparing the above-mentioned cold-resistant and salt-resistant concrete admixture, which specifically includes the following steps:

[0058] (1) Modified nano-montmorillonite was uniformly dispersed in 5 times its mass of water to obtain mixture I;

[0059] (2) Mix water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol with water at a mass of 5 times the total mass of water-reducing agent, antifreeze agent, calcium carbonate, and polyvinyl alcohol to obtain mixture II;

[0060] (3) Mix liquid I and mixture liquid II, add a modifier, microwave-assisted heating treatment for 20 minutes, microwave power of 500W, heating temperature of 55℃, and finally dry to obtain cold-resistant and salt-resistant concrete admixture.

[0061] Example 2

[0062] The cold-resistant and salt-resistant concrete admixture, by weight percentage, is made of 30% water-reducing agent, 42% antifreeze agent, 12% calcium carbonate, 5% polyvinyl alcohol (molecular weight 150,000), 4% modified nano montmorillonite, 3% triisostearoyl titanate isopropyl ester coupling agent, and the balance being a blending agent.

[0063] The antifreeze contains diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in a mass ratio of 3:2:1.

[0064] The water-reducing agent is sodium lignosulfonate.

[0065] The blending agent comprises polyoxypropylene ethylene glycerol ether defoamer, rosin soap air-entraining agent, and polyacrylamide thickener in a mass ratio of 1:2:1.

[0066] The modified nano-montmorillonite was prepared by the following method:

[0067] One part by weight of nano-montmorillonite was added to 10 parts by weight of an aqueous solution containing 20% ​​acetic acid and 2% citric acid by mass. The solution was treated at 70°C for 30 min. After removal, the solution was washed with water until neutral. Then, it was added to 8 parts by weight of dimethylacetamide, along with 0.1 parts by weight of polyethylene glycol diglycidyl ether and 0.08 parts by weight of glycerol. The solution was reacted at 70°C for 2 h. After the reaction was completed, the solution was removed and dried to obtain modified nano-montmorillonite.

[0068] This embodiment also provides a method for preparing the above-mentioned cold-resistant and salt-resistant concrete admixture, including the following steps:

[0069] (1) Modified nano-montmorillonite was uniformly dispersed in 5 times its mass of water to obtain mixture I;

[0070] (2) Mix water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol with water at a mass of 5 times the total mass of water-reducing agent, antifreeze agent, calcium carbonate, and polyvinyl alcohol to obtain mixture II;

[0071] (3) Mix liquid I and mixture liquid II, add a modifier, microwave-assisted heating treatment for 30 minutes, microwave power of 400W, heating temperature of 55℃, and finally dry to obtain cold-resistant and salt-resistant concrete admixture.

[0072] Example 3

[0073] The cold-resistant and salt-resistant concrete admixture is made by weight percentage of 50% water-reducing agent, 30% antifreeze agent, 6.5% calcium carbonate, 5% polyvinyl alcohol (molecular weight 150,000), 8% modified nano montmorillonite, and 0.5% distearate coupling agent.

[0074] The mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoryltriamine, and copper 2-ethylhexanoate in the antifreeze is 4.2:3:1.2.

[0075] The water-reducing agent is sodium aminosulfonate.

[0076] The modified nano-montmorillonite was prepared by the following method:

[0077] One part by weight of nano-montmorillonite was added to 10 parts by weight of an aqueous solution containing 10% acetic acid and 5% citric acid by mass. The solution was treated at 70°C for 30 min. After removal, the solution was washed with water until neutral. Then, it was added to 8 parts by weight of dimethylacetamide, along with 0.15 parts by weight of polyethylene glycol diglycidyl ether and 0.05 parts by weight of glycerol. The solution was reacted at 70°C for 2 h. After the reaction was completed, the solution was removed and dried to obtain modified nano-montmorillonite.

[0078] This embodiment also provides a method for preparing the above-mentioned cold-resistant and salt-resistant concrete admixture, including the following steps:

[0079] (1) Modified nano-montmorillonite was uniformly dispersed in 5 times its mass of water to obtain mixture I;

[0080] (2) Mix water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol with water at a mass of 5 times the total mass of water-reducing agent, antifreeze agent, calcium carbonate, and polyvinyl alcohol to obtain mixture II;

[0081] (3) Mix liquid I and mixture liquid II are mixed and microwave-assisted heating treatment is performed for 30 minutes. The microwave power is 400W and the heating temperature is 55℃. Finally, the mixture is dried to obtain the cold-resistant and salt-resistant concrete admixture.

[0082] Example 4

[0083] The cold-resistant and salt-resistant concrete admixture, by weight percentage, is made of 38% water-reducing agent, 36% antifreeze agent, 8% calcium carbonate, 7% polyvinyl alcohol (molecular weight 150,000), 7.5% modified nano montmorillonite, 2% propyltriethoxysilane coupling agent, and the balance being a blending agent.

[0084] The mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 5:3.4:1.4.

[0085] The water-reducing agent is sodium aminosulfonate.

[0086] The blending agent comprises polyoxypropylene ethylene glycerol ether defoamer, sodium dodecyl sulfate air-entraining agent, and hydroxyethyl cellulose ether thickener in a mass ratio of 1:1:1.

[0087] The modified nano-montmorillonite was prepared by the following method:

[0088] One part by weight of nano-montmorillonite was added to 10 parts by weight of an aqueous solution containing 14% acetic acid and 4% citric acid by mass. The solution was treated at 65°C for 40 min. After removal, the solution was washed with water until neutral. Then, it was added to 8 parts by weight of dimethylacetamide, along with 0.13 parts by weight of polyethylene glycol diglycidyl ether and 0.06 parts by weight of glycerol. The solution was reacted at 70°C for 1 h. After the reaction was completed, the solution was removed and dried to obtain modified nano-montmorillonite.

[0089] This embodiment also provides a method for preparing the above-mentioned cold-resistant and salt-resistant concrete admixture, including the following steps:

[0090] (1) Modified nano-montmorillonite was uniformly dispersed in 5 times its mass of water to obtain mixture I;

[0091] (2) Mix water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol with water at a mass of 5 times the total mass of water-reducing agent, antifreeze agent, calcium carbonate, and polyvinyl alcohol to obtain mixture II;

[0092] (3) Mix liquid I and mixture liquid II, add a modifier, microwave-assisted heating treatment for 20 minutes, microwave power of 500W, heating temperature of 55℃, and finally dry to obtain cold-resistant and salt-resistant concrete admixture.

[0093] Example 5

[0094] The cold-resistant and salt-resistant concrete admixture, by weight percentage, is made of 45% water-reducing agent, 32% antifreeze agent, 6% calcium carbonate, 5% polyvinyl alcohol (molecular weight 150,000), 6% modified nano-montmorillonite, 1% propyltriethoxysilane coupling agent, and the balance being a blending agent.

[0095] The antifreeze contains diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in a mass ratio of 6:4:1.8.

[0096] The water-reducing agent is sodium aminosulfonate.

[0097] The blending agent comprises polyoxypropylene ethylene glycerol ether defoamer, sodium dodecyl sulfate air-entraining agent, and hydroxyethyl cellulose ether thickener in a mass ratio of 1:1:1.

[0098] The modified nano-montmorillonite was prepared by the following method:

[0099] One part by weight of nano-montmorillonite was added to 10 parts by weight of an aqueous solution containing 14% acetic acid and 4% citric acid by mass. The solution was treated at 65°C for 40 min. After removal, the solution was washed with water until neutral. Then, it was added to 8 parts by weight of dimethylacetamide, along with 0.13 parts by weight of polyethylene glycol diglycidyl ether and 0.06 parts by weight of glycerol. The solution was reacted at 70°C for 1 h. After the reaction was completed, the solution was removed and dried to obtain modified nano-montmorillonite.

[0100] This embodiment also provides a method for preparing the above-mentioned cold-resistant and salt-resistant concrete admixture, including the following steps:

[0101] (1) Modified nano-montmorillonite was uniformly dispersed in 5 times its mass of water to obtain mixture I;

[0102] (2) Mix water-reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol with water at a mass of 5 times the total mass of water-reducing agent, antifreeze agent, calcium carbonate, and polyvinyl alcohol to obtain mixture II;

[0103] (3) Mix liquid I and mixture liquid II, add a modifier, microwave-assisted heating treatment for 20 minutes, microwave power of 500W, heating temperature of 55℃, and finally dry to obtain cold-resistant and salt-resistant concrete admixture.

[0104] Comparative Example 1

[0105] The difference from Example 1 is that the mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and 2-ethylhexanoate in the antifreeze is 2:5:2, while all other aspects are the same.

[0106] Comparative Example 2

[0107] The difference from Example 1 is that the mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 7:1:0.5, while all other aspects are the same.

[0108] Comparative Example 3

[0109] The difference from Example 1 is that the antifreeze does not contain diethylene glycol butyl ether acetate, but all other aspects are the same.

[0110] Comparative Example 4

[0111] The difference from Example 1 is that the antifreeze does not contain hexaethylphosphoric triamine, but all other aspects are the same.

[0112] Comparative Example 5

[0113] The difference from Example 1 is that the antifreeze does not contain copper 2-ethylhexanoate, but all other aspects are the same.

[0114] Comparative Example 6

[0115] The difference from Example 1 is that the polyethylene glycol diglycidyl ether in the modified nano-montmorillonite is replaced with polypropylene glycol diglycidyl ether, while the rest are the same.

[0116] Comparative Example 7

[0117] The difference from Example 1 is that the modified nano-montmorillonite is replaced with acid-treated nano-montmorillonite, while the rest are the same.

[0118] Comparative Example 8

[0119] The difference from Example 1 is that the modified nano-montmorillonite was replaced with unmodified nano-montmorillonite, while all other aspects are the same.

[0120] Comparative Example 9

[0121] The difference from Example 1 is that no microwave-assisted heating treatment is used in the preparation process of the cold-resistant and salt-resistant concrete admixture; all other aspects are the same.

[0122] Application examples

[0123] Mix 50 parts of cement, 36 parts of aggregate and 70 parts of water, add 4 parts of the cold-resistant and salt-resistant concrete admixture obtained in the above examples and comparative examples, mix evenly to obtain concrete, and use the group without adding the cold-resistant and salt-resistant concrete admixture as a blank group, and conduct the following experimental tests.

[0124] 1. Compressive strength

[0125] The compressive strength of concrete was tested according to GB / T50081-2019 "Test Methods for Mechanical Properties of Ordinary Concrete", and the results are shown in Table 1 below.

[0126] Table 1. Compressive Strength

[0127]

[0128] The results showed that the compressive strength of concrete was significantly improved after adding the admixture of the present invention compared with that of concrete without admixture (blank group). The compressive strength of concrete corresponding to Comparative Examples 1 and 2 was significantly lower than that of Example 1. It can be seen that using diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in a certain proportion as antifreeze agents can improve the compressive strength in addition to improving the frost resistance of concrete. In addition, the compressive strength of Comparative Examples 6-8 and Comparative Example 9 was also lower than that of Example 1. It can be seen that the addition of modified nano-montmorillonite and the microwave heating treatment in the preparation process of admixture can help improve the compressive strength of concrete.

[0129] 2. Cold resistance

[0130] Referring to the slow freezing method in GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the concrete was subjected to 100 freeze-thaw cycles. After the freeze-thaw treatment, the mass loss rate (%) and compressive strength loss rate (%) of the concrete were measured. The results are shown in Table 2 below.

[0131] Table 2. Cold resistance performance

[0132] Group Quality loss rate (%) Compressive strength loss rate (%) Example 1 0.21 5.83 Example 2 0.24 5.95 Example 3 0.22 5.82 Example 4 0.21 5.97 Example 5 0.23 6.02 Comparative Example 1 0.94 10.27 Comparative Example 2 1.01 10.85 Comparative Example 3 1.37 13.75 Comparative Example 4 1.30 14.22 Comparative Example 5 1.35 13.91 Comparative Example 6 0.32 6.21 Comparative Example 7 0.29 6.23 Comparative Example 8 0.35 6.47 Comparative Example 9 0.80 9.17 Blank group 2.27 19.85

[0133] The results showed that without the admixture (blank group), the concrete had a high rate of mass loss and compressive strength loss after 100 freeze-thaw cycles. However, with the admixture of the present invention, the mass loss and compressive strength loss of the concrete after 100 freeze-thaw cycles were significantly reduced, indicating that the admixture of the present invention enhances the cold resistance and frost protection of concrete. In addition, the concrete corresponding to Comparative Examples 1-5 showed a significant difference in mass loss and compressive strength loss after 100 freeze-thaw cycles compared with the examples, indicating that diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate, as antifreeze agents, have a certain synergistic effect and can improve the cold resistance and frost protection of concrete. Further optimization of the dosage ratio of the three can further improve the cold resistance and frost protection of concrete.

[0134] 3. Salt corrosion resistance

[0135] Referring to the rapid chloride ion migration coefficient method in GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the concrete obtained by this invention was subjected to erosion after 28 days of curing, and the chloride ion penetration resistance coefficient of the concrete was determined. Then, it was subjected to a wet-dry cycle test in a 5% sodium chloride solution and an indoor environment at 25°C. After 60 days and 120 days of the experiment, the chloride ion penetration depth of the concrete after 60 days and 120 days of wet-dry cycle-chloride erosion was tested. The results are shown in Table 3 below.

[0136] Table 3. Salt corrosion resistance

[0137]

[0138] The results showed that the diffusion coefficient of concrete without admixtures was 20.2 × 10⁻⁶. -12 m 2 / s, while the diffusion coefficient was significantly reduced after adding the admixture of the present invention, and the chloride ion penetration depth was significantly reduced after 60d and 120d of dry-wet cycle-chloride ion erosion. It can be seen that the admixture provided by the present invention can significantly improve the impermeability of concrete when added to concrete. The diffusion coefficient and chloride ion penetration depth of comparative examples 6-8 after 60d and 120d of dry-wet cycle-chloride ion erosion are higher than those of example 1, that is, the impermeability is relatively poor. It can be seen that montmorillonite, after modification treatment, can significantly improve the impermeability of concrete when added to concrete. In addition, the impermeability of comparative examples 1-2 and 9 is also reduced to a certain extent compared with example 1, indicating that the content ratio of the three components in the antifreeze agent and the microwave heating treatment in the preparation process of the admixture can improve the impermeability of concrete to a certain extent.

[0139] 4. Crack resistance

[0140] Referring to GB / T50080-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the early cracking performance of concrete was studied using a flat mold with dimensions of 600mm×600mm×50mm and room temperature. The results of the number of cracks and the total crack area are shown in Table 4 below.

[0141] Table 4. Crack resistance

[0142] Group Number of cracks <![CDATA[Total crack area (mm 2 )]]> Example 1 2 42.6 Comparative Example 6 9 90.2 Comparative Example 7 10 87.5 Comparative Example 8 7 96.4 Blank group 14 115.7

[0143] The results showed that the number of cracks and the total crack area of ​​the concrete corresponding to Comparative Examples 6-8 were similar, but significantly different from Example 1. This indicates that the addition of nano-montmorillonite modified with polyethylene glycol diglycidyl ether in this invention helps to improve the crack resistance of concrete.

[0144] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A cold-resistant and salt-resistant concrete admixture, characterized in that, It consists of the following components by weight percentage: 30%-50% water-reducing agent, 30%-42% antifreeze agent, 5%-12% calcium carbonate, 5%-10% polyvinyl alcohol, 4%-8% modified nano-montmorillonite, 0.5%-3% coupling agent, and the balance being a blending agent; The mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 3-6:2-4:1-1.

8. The preparation method of the modified nano-montmorillonite includes the following steps: Nano-montmorillonite was pretreated with acid, then washed with water until neutral, and then added to a solvent. Polyethylene glycol diglycidyl ether and glycerol were added to carry out a modification reaction to obtain modified nano-montmorillonite. The blending agent is selected from at least one of defoamers, air-entraining agents, and thickeners; The preparation method of the cold-resistant and salt-resistant concrete admixture includes the following steps: (1) Modified nano-montmorillonite is uniformly dispersed in water to obtain mixture I; (2) The water-reducing agent, antifreeze, calcium carbonate, polyvinyl alcohol and water are mixed evenly to obtain mixture II; (3) Mix the mixture I obtained in step (1) with the mixture II obtained in step (2), microwave-assisted heating treatment, and drying to obtain cold-resistant and salt-resistant concrete admixture; In step (3), a modifier is added before the microwave-assisted heating treatment.

2. The cold-resistant and salt-resistant concrete admixture according to claim 1, characterized in that, It consists of the following components by weight percentage: water-reducing agent 38%-45%, antifreeze agent 32%-36%, calcium carbonate 6%-8%, polyvinyl alcohol 5%-7%, modified nano-montmorillonite 6%-7.5%, coupling agent 1%-2%, and the balance being a blending agent.

3. The cold-resistant and salt-resistant concrete admixture according to claim 2, characterized in that, It consists of the following components by weight percentage: 43% water-reducing agent, 33% antifreeze agent, 7.5% calcium carbonate, 6.8% polyvinyl alcohol, 7.2% modified nano-montmorillonite, 1.2% coupling agent, and the balance being a blending agent.

4. The cold-resistant and salt-resistant concrete admixture according to claim 1, characterized in that, The water-reducing agent is selected from at least one of polycarboxylate water-reducing agents, naphthalene water-reducing agents, melamine water-reducing agents, lignin sulfonate water-reducing agents, aminosulfonate water-reducing agents, and fatty acid water-reducing agents.

5. The cold-resistant and salt-resistant concrete admixture according to claim 1, characterized in that, The mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and copper 2-ethylhexanoate in the antifreeze is 4.2-5:3-3.4:1.2-1.

4.

6. The cold-resistant and salt-resistant concrete admixture according to claim 5, characterized in that, The mass ratio of diethylene glycol butyl ether acetate, hexaethylphosphoric triamine, and 2-ethylhexanoate is 4.6:3.3:1.

3.

7. The cold-resistant and salt-resistant concrete admixture according to claim 1, characterized in that, The acid solution is a mixed aqueous solution of acetic acid and citric acid; the mass fraction of acetic acid in the acid solution is 10%-20%, and the mass fraction of citric acid is 2%-5%.

8. The cold-resistant and salt-resistant concrete admixture according to claim 7, characterized in that, The amount of polyethylene glycol diglycidyl ether added is 10%-15% of the mass of the nano-montmorillonite, and the amount of glycerol added is 1%-5% of the mass of the nano-montmorillonite.

9. The method for preparing the cold-resistant and salt-resistant concrete admixture according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Modified nano-montmorillonite is uniformly dispersed in water to obtain mixture I; (2) The water-reducing agent, antifreeze, calcium carbonate, polyvinyl alcohol and water are mixed evenly to obtain mixture II; (3) Mix the mixture I obtained in step (1) with the mixture II obtained in step (2), microwave-assisted heating treatment, and drying to obtain cold-resistant and salt-resistant concrete admixture; In step (3), a modifier is added before the microwave-assisted heating treatment.

10. The preparation method according to claim 9, characterized in that, In step (3), the microwave power of the microwave-assisted heating treatment is 300-600W, the heating temperature is 45-60℃, and the time is 5-40min.

11. The application of cold-resistant and salt-resistant concrete admixtures in cold-resistant and salt-resistant concrete, characterized in that, The cold-resistant and salt-resistant concrete admixture is the cold-resistant and salt-resistant concrete admixture according to any one of claims 1-8 or the cold-resistant and salt-resistant concrete admixture prepared by the preparation method according to any one of claims 9-10.

12. The application according to claim 11, characterized in that, The mass fraction of the cold-resistant and salt-resistant concrete admixture added to the cold-resistant and salt-resistant concrete is 0.05%-5%.

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