Cold-resistant and salt-resistant concrete admixture as well as preparation method and application thereof

Abstract

The invention provides a cold-resistant and salt-resistant concrete admixture as well as a preparation method and application thereof, and belongs to the technical field of buildings and civil engineering. The concrete admixture comprises a water reducing agent, an anti-freezing agent, calcium carbonate, polyvinyl alcohol, modified nano montmorillonite and a coupling agent, wherein the anti-freezing agent is diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate. By compounding the components, the compactness of the concrete is effectively improved, so that the concrete provided by the invention has better cold resistance, freezing resistance, impermeability and salt corrosion resistance, and the strength of the concrete can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of construction and civil engineering, and specifically relates to a cold-resistant and salt-resistant concrete admixture and a preparation method and application thereof. Background Art

[0002] Concrete is one of the most widely used building materials at present, and plays an irreplaceable role in the construction of roads, bridges, buildings, ports, docks and dams. In actual application, concrete is easily affected by the climate environment, such as rain erosion, wind erosion, freeze-thaw, etc., and actual engineering components often crack due to load during service, increasing the corrosion salt entering the internal channels of concrete, resulting in the destruction of concrete structure, reduced strength, poor durability, and greatly reduced service life. Adding admixtures to concrete is one of the most effective ways to improve and improve the various properties of concrete and meet the durability requirements of engineering.

[0003] There are many types of concrete admixtures, and different types have different effects. For example, water reducers and air entraining agents can improve the rheological properties of concrete mixtures, while retarders, early strength agents and accelerated setting agents can adjust the setting time and hardening properties of concrete. However, the type of concrete additives and the way they are added can seriously 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, a sodium β-naphthylsulfonate formaldehyde condensate, sodium sulfate, triethanolamine, an alkylbenzene sulfonate, ethylene glycol, propylene glycol, silicone and water. The concrete additive has the effects of water seepage prevention and impact resistance, and can improve the strength and friction resistance of concrete.

[0005] Chinese patent application 202111401474.3 discloses a concrete admixture and a preparation method thereof, comprising a water reducing agent mother liquor, sodium alginate, lignin sulfonate, potassium acrylate, polyethylene glycol, sodium silicate, a first deionized water and other additives; through the synergistic effect of each component, the water 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 resistance, waterproof and other properties.

[0006] Although there are many concrete admixtures on the market, there are still some defects in practical application. For example, although the water reduction effect is good, it will increase the water seepage rate, affect the quality of concrete, destroy the salt corrosion resistance and frost resistance of concrete, and reduce the strength and wear resistance of concrete. Therefore, it is necessary to study new concrete admixtures. Summary of the invention

[0007] The purpose of the present invention is to provide a cold-resistant and salt-resistant concrete admixture and its preparation method and application in view of the deficiencies in the prior art. Through the interaction of various components, the cold-resistant and frost-resistant properties, salt erosion resistance, cracking resistance and compressive strength of concrete can be significantly improved, and the engineering durability requirements for concrete under low temperature conditions can be met.

[0008] The present invention achieves the above-mentioned purpose 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; wherein:

[0010] The antifreeze agent comprises diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate.

[0011] Preferably, the cold-resistant and salt-resistant concrete admixture consists of a water reducer, 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 ingredients by weight percentage: 30%-50% of water reducing agent, 30%-42% of antifreeze agent, 5%-12% of calcium carbonate, 5%-10% of polyvinyl alcohol, 4%-8% of nano-montmorillonite, 0.5%-3% of coupling agent and the remainder of a blending agent.

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

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

[0015] Further, the water reducer is selected from at least one of polycarboxylic acid water reducer, naphthalene water reducer, melamine water reducer, lignin sulfonate water reducer, aminosulfonate water reducer and fatty acid water reducer. Preferably, the water reducer is selected from at least one of melamine water reducer, sodium lignin sulfonate water reducer and sodium aminosulfonate water reducer.

[0016] Furthermore, the mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite 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, hexaethyl phosphoramidite 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, hexaethyl phosphoramidite and copper 2-ethylhexanoate in the antifreeze is 4.6:3.3:1.3.

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

[0020] Further, the coupling agent is selected from at least one of a silane coupling agent, a titanate coupling agent or an aluminate coupling agent; preferably, the coupling agent is selected from at least one of γ-glycidyloxypropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, triisostearoyl isopropyl titanate and distearoyloxyisopropyl aluminate.

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

[0022] The nano-montmorillonite is pretreated with acid solution, taken out and washed with water to neutrality, then added into a solvent, and polyethylene glycol diglycidyl ether and glycerol are added to carry out 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 the nano-montmorillonite to the acid solution is 1:10-20; preferably, the mass ratio is 1:10-15.

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

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

[0027] Furthermore, in the preparation process of the 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 addition amount of polyethylene glycol diglycidyl ether is 10%-15% of the mass of the nano-montmorillonite; preferably, the addition amount of polyethylene glycol diglycidyl ether is 12%-13.5% of the mass of the nano-montmorillonite.

[0029] Furthermore, in the preparation process of the modified nano-montmorillonite, the added amount of the glycerol is 1%-5% of the mass of the nano-montmorillonite; preferably, the added amount of the glycerol 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 0.5-2h, and the reaction temperature is 60-70°C; preferably, the modification reaction time is 1-1.5h, and the reaction temperature is 65-70°C.

[0031] Furthermore, the conditioning agent is selected from at least one of a defoaming agent, an air entraining agent and a thickener.

[0032] Furthermore, the defoamer is selected from at least one of polyethers, silicones and polyether-modified silicone oils. The defoamer plays a role in eliminating bubbles in the concrete softener, and is preferably at least one of polyoxypropylene glycerol ether, polyoxyethylene glycerol ether, polyoxypropylene oxyethylene 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 lignin sulfonate, 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 the role of water retention, thickening and anti-sagging; preferably, it is 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 comprises the following steps:

[0036] (1) The modified nano-montmorillonite is uniformly dispersed in water to obtain a mixed solution I;

[0037] (2) mixing the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water uniformly to obtain a mixed solution II;

[0038] (3) The mixed solution I obtained in step (1), the mixed solution II obtained in step (2) and a blending agent are mixed, subjected to microwave-assisted heating treatment, and dried to obtain a cold-resistant and salt-resistant concrete admixture.

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

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

[0041] On the other hand, the above-mentioned cold-resistant and salt-resistant concrete admixture is 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 compactness of concrete by compounding water reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano-montmorillonite and a blending agent, so that the concrete provided by the present invention has good cold and frost resistance, impermeability and salt corrosion resistance, and can also improve the strength of concrete.

[0045] (2) The present invention uses diethylene glycol butyl acetate, hexaethyl phosphoramidite, and copper 2-ethylhexanoate as antifreeze agents. Through the synergistic effect of the three, the cold and frost resistance of concrete can be significantly improved; the dosage ratio of the three is further optimized, while improving the cold and frost resistance of concrete, the dispersibility of the admixture on concrete particles can be further improved, and the performance of the concrete after adding the admixture is further enhanced, thereby improving the strength and salt erosion resistance of the concrete.

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

[0047] (4) In the process of preparing the concrete admixture, the present invention utilizes microwave-assisted heating treatment, which helps to evenly disperse the concrete admixture, thereby exerting the role of each component and improving the overall performance of the concrete. DETAILED DESCRIPTION

[0048] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0049] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels.

[0050] Example 1

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

[0052] The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite 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 a polyoxypropylene oxyethylene glycerol ether defoamer, a sodium lauryl sulfate air entrainer and a hydroxyethyl cellulose ether thickener in a mass ratio of 1:1:1.

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

[0056] 1 part by weight of nano-montmorillonite is added to 10 parts by weight of an aqueous solution containing 14% by weight of acetic acid and 4% by weight of citric acid, treated at 65°C for 40 minutes, taken out and washed with water until neutral, then added to 8 parts by weight of dimethylacetamide, 0.13 parts by weight of polyethylene glycol diglycidyl ether and 0.06 parts by weight of glycerol are added, reacted at 70°C for 1 hour, taken out after the reaction is complete and dried to obtain the modified nano-montmorillonite.

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

[0058] (1) The modified nano-montmorillonite is uniformly dispersed in water with a mass of 5 times the mass of the water to obtain a mixed solution I;

[0059] (2) the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water having a mass 5 times the total mass of the water reducer, antifreeze agent, calcium carbonate and polyvinyl alcohol are uniformly mixed to obtain a mixed solution II;

[0060] (3) Mixed solution I and mixed solution II were mixed, a blending agent was added, and microwave-assisted heating was performed for 20 min, with a microwave power of 500 W and a heating temperature of 55° C. Finally, the mixture was dried to obtain a cold-resistant and salt-resistant concrete admixture.

[0061] Example 2

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

[0063] The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate in the antifreeze is 3:2:1.

[0064] The water reducing agent is sodium lignin sulfonate.

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

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

[0067] 1 part by weight of nano-montmorillonite is added to 10 parts by weight of an aqueous solution containing 20% ​​by weight of acetic acid and 2% by weight of citric acid, treated at 70°C for 30 minutes, taken out and washed with water until neutral, then added to 8 parts by weight of dimethylacetamide, 0.1 parts by weight of polyethylene glycol diglycidyl ether and 0.08 parts by weight of glycerol are added, reacted at 70°C for 2 hours, taken out after the reaction is complete and dried to obtain the modified nano-montmorillonite.

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

[0069] (1) The modified nano-montmorillonite is uniformly dispersed in water with a mass of 5 times the mass of the water to obtain a mixed solution I;

[0070] (2) the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water having a mass 5 times the total mass of the water reducer, antifreeze agent, calcium carbonate and polyvinyl alcohol are uniformly mixed to obtain a mixed solution II;

[0071] (3) Mixed solution I and mixed solution II were mixed, a blending agent was added, and microwave-assisted heating was performed for 30 min, with a microwave power of 400 W and a heating temperature of 55° C. Finally, the mixture was dried to obtain a cold-resistant and salt-resistant concrete admixture.

[0072] Example 3

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

[0074] The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite 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 is prepared by the following method:

[0077] 1 part by weight of nano-montmorillonite is added to 10 parts by weight of an aqueous solution containing 10% by weight of acetic acid and 5% by weight of citric acid, treated at 70°C for 30 minutes, taken out and washed with water until neutral, then added to 8 parts by weight of dimethylacetamide, 0.15 parts by weight of polyethylene glycol diglycidyl ether and 0.05 parts by weight of glycerol are added, reacted at 70°C for 2 hours, taken out after the reaction is complete and dried to obtain the modified nano-montmorillonite.

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

[0079] (1) The modified nano-montmorillonite is uniformly dispersed in water with a mass of 5 times the mass of the water to obtain a mixed solution I;

[0080] (2) the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water having a mass 5 times the total mass of the water reducer, antifreeze agent, calcium carbonate and polyvinyl alcohol are uniformly mixed to obtain a mixed solution II;

[0081] (3) Mixed solution I and mixed solution II are mixed, subjected to microwave-assisted heating for 30 min, with a microwave power of 400 W and a heating temperature of 55° C., and finally dried to obtain a cold-resistant and salt-resistant concrete admixture.

[0082] Example 4

[0083] The cold-resistant and salt-resistant concrete admixture is made of 38% of water reducing agent, 36% of antifreeze agent, 8% of calcium carbonate, 7% of polyvinyl alcohol (molecular weight 150,000), 7.5% of modified nano-montmorillonite, 2% of 3-isocyanatepropyltriethoxysilane coupling agent and the balance of a blending agent, calculated by weight percentage.

[0084] The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite 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 a polyoxypropylene oxyethylene glycerol ether defoamer, a sodium lauryl sulfate air entrainer and a hydroxyethyl cellulose ether thickener in a mass ratio of 1:1:1.

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

[0088] 1 part by weight of nano-montmorillonite is added to 10 parts by weight of an aqueous solution containing 14% by weight of acetic acid and 4% by weight of citric acid, treated at 65°C for 40 minutes, taken out and washed with water until neutral, then added to 8 parts by weight of dimethylacetamide, 0.13 parts by weight of polyethylene glycol diglycidyl ether and 0.06 parts by weight of glycerol are added, reacted at 70°C for 1 hour, taken out after the reaction is complete and dried to obtain the modified nano-montmorillonite.

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

[0090] (1) The modified nano-montmorillonite is uniformly dispersed in water with a mass of 5 times the mass of the water to obtain a mixed solution I;

[0091] (2) the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water having a mass 5 times the total mass of the water reducer, antifreeze agent, calcium carbonate and polyvinyl alcohol are uniformly mixed to obtain a mixed solution II;

[0092] (3) Mixed solution I and mixed solution II were mixed, a blending agent was added, and microwave-assisted heating was performed for 20 min, with a microwave power of 500 W and a heating temperature of 55° C. Finally, the mixture was dried to obtain a cold-resistant and salt-resistant concrete admixture.

[0093] Example 5

[0094] The cold-resistant and salt-resistant concrete admixture is made of 45% of water reducing agent, 32% of antifreeze agent, 6% of calcium carbonate, 5% of polyvinyl alcohol (molecular weight 150,000), 6% of modified nano-montmorillonite, 1% of 3-isocyanatepropyltriethoxysilane coupling agent and the balance of a blending agent, calculated by weight percentage.

[0095] The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate in the antifreeze is 6:4:1.8.

[0096] The water reducing agent is sodium aminosulfonate.

[0097] The blending agent comprises a polyoxypropylene oxyethylene glycerol ether defoamer, a sodium lauryl sulfate air entrainer and a hydroxyethyl cellulose ether thickener in a mass ratio of 1:1:1.

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

[0099] 1 part by weight of nano-montmorillonite is added to 10 parts by weight of an aqueous solution containing 14% by weight of acetic acid and 4% by weight of citric acid, treated at 65°C for 40 minutes, taken out and washed with water until neutral, then added to 8 parts by weight of dimethylacetamide, 0.13 parts by weight of polyethylene glycol diglycidyl ether and 0.06 parts by weight of glycerol are added, reacted at 70°C for 1 hour, taken out after the reaction is complete and dried to obtain the modified nano-montmorillonite.

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

[0101] (1) The modified nano-montmorillonite is uniformly dispersed in water with a mass of 5 times the mass of the water to obtain a mixed solution I;

[0102] (2) the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water having a mass 5 times the total mass of the water reducer, antifreeze agent, calcium carbonate and polyvinyl alcohol are uniformly mixed to obtain a mixed solution II;

[0103] (3) Mixed solution I and mixed solution II were mixed, a blending agent was added, and microwave-assisted heating was performed for 20 min, with a microwave power of 500 W and a heating temperature of 55° C. Finally, the mixture was dried to obtain a 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 acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate in the antifreeze agent is 2:5:2, and the rest are the same.

[0106] Comparative Example 2

[0107] The difference from Example 1 is that the mass ratio of diethylene glycol butyl acetate, hexaethyl phosphoramidite, and copper 2-ethylhexanoate in the antifreeze is 7:1:0.5, and the rest 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, and the rest is the same.

[0110] Comparative Example 4

[0111] The difference from Example 1 is that the antifreeze does not contain hexaethylphosphoramide, and the rest is the same.

[0112] Comparative Example 5

[0113] The difference from Example 1 is that the antifreeze does not contain copper 2-ethylhexanoate, and the rest is 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 by polypropylene glycol diglycidyl ether, and the rest is the same.

[0116] Comparative Example 7

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

[0118] Comparative Example 8

[0119] The difference from Example 1 is that the modified nano-montmorillonite is replaced by unmodified nano-montmorillonite, and the rest are the same.

[0120] Comparative Example 9

[0121] The difference from Example 1 is that during the preparation of the cold-resistant and salt-resistant concrete admixture, no microwave-assisted heating treatment is performed, and the rest is 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 well, and make concrete. The blank group without adding the cold-resistant and salt-resistant concrete admixture is used for the following experimental tests.

[0124] 1. Compressive strength

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

[0126] Table 1. Compressive strength

[0127]

[0128] The results show that compared with the compressive strength of concrete without adding admixture (blank group), the compressive strength is significantly improved after adding the admixture of the present invention; the compressive strength of the concrete corresponding to Comparative Examples 1 and 2 is significantly lower than that of the embodiment, which shows that using diethylene glycol butyl acetate, hexaethyl phosphoramidite, and copper 2-ethylhexanoate in a certain dosage ratio as antifreeze agents can not only improve the frost resistance of concrete, but also help to improve the compressive strength; in addition, the compressive strength of Comparative Examples 6-8 and Comparative Example 9 is also lower than that of Example 1, which shows that the addition of modified nano-montmorillonite and the microwave heating treatment in the preparation process of the admixture can help to improve the compressive strength of concrete.

[0129] 2. Cold resistance

[0130] With reference 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 cycles, the mass loss rate (%) and compressive strength loss rate (%) of the concrete were tested. The results are shown in Table 2 below.

[0131] Table 2. Cold resistance performance

[0132] Group Mass 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 show that when no admixture is added to the concrete (blank group), the mass loss rate and compressive strength loss rate after 100 freeze-thaw treatments are high, while after adding the admixture of the present invention, the mass loss rate and compressive strength loss rate of the concrete after 100 freeze-thaw treatments are significantly reduced, which shows that the admixture of the present invention has the effect of enhancing the cold and frost resistance of the concrete; in addition, the mass loss rate and compressive strength loss rate of the concrete corresponding to Comparative Examples 1-5 after 100 freeze-thaw treatments are significantly different from those of the embodiment, which shows that diethylene glycol butyl acetate, hexaethyl phosphoramidite and 2-ethylhexanoate copper are used as antifreeze agents, and the three have a certain synergistic effect to improve the cold and frost resistance of the concrete. Further optimizing the dosage ratio of the three can further improve the cold and frost resistance of the concrete.

[0134] 3. Salt corrosion resistance

[0135] With reference to the rapid chloride ion migration coefficient method in GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", the concrete obtained by the present invention was corroded after curing for 28 days, and the concrete chloride ion permeability coefficient was measured; then, a dry-wet cycle test was performed in a 5% sodium chloride solution and an indoor environment of 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 dry-wet cycle-chloride ion corrosion was tested, and the results are shown in Table 3 below.

[0136] Table 3. Salt corrosion resistance

[0137]

[0138] The results show that the diffusion coefficient of concrete without admixture is 20.2×10 -12 m 2 / s, while after adding the admixture of the present invention, the diffusion coefficient is significantly reduced, and the chloride ion penetration depth after dry-wet cycle-chloride ion corrosion for 60d and 120d is significantly reduced. It can be seen that the admixture provided by the present invention added to concrete can significantly improve the impermeability of concrete. The diffusion coefficient and the chloride ion penetration depth after dry-wet cycle-chloride ion corrosion for 60d and 120d of comparative examples 6-8 are higher than those of Example 1, that is, the impermeability is relatively poor. It can be seen that the impermeability of concrete can be greatly improved after montmorillonite is added to concrete after modification. In addition, the impermeability of comparative examples 1-2 and 9 is also reduced to a certain extent compared with that of 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. Anti-cracking performance

[0140] With reference to GB / T50080-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", a flat plate mold was used to study the early cracking performance of concrete. The size of the mold was 600mm×600mm×50mm, and the experimental temperature was room temperature. The results of the measured crack number and total crack area are shown in Table 4 below.

[0141] Table 4. Cracking 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 show that the number of cracks and the total crack area of ​​the concrete corresponding to Comparative Examples 6-8 are slightly different, but are significantly different from those of Example 1. It can be seen that the addition of nano-montmorillonite modified with polyethylene glycol diglycidyl ether in the present invention helps to improve the anti-cracking performance of concrete.

[0144] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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 present invention should be within the scope of protection of the present invention.

Claims

1. A cold and salt resistant concrete admixture, It is characterized in that Including water reducing agent, antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano-montmorillonite and coupling agent; among which, The antifreeze agent comprises diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate.

2. The cold and salt resistant concrete admixture according to claim 1, It is characterized in that It consists of a water reducing agent, an antifreeze agent, calcium carbonate, polyvinyl alcohol, modified nano-montmorillonite, a coupling agent and a blending agent.

3. The cold and salt resistant concrete admixture according to claim 1, It is characterized in that The invention is composed of the following components by weight percentage: 30%-50% of water reducing agent, 30%-42% of antifreeze agent, 5%-12% of calcium carbonate, 5%-10% of polyvinyl alcohol, 4%-8% of modified nano-montmorillonite, 0.5%-3% of coupling agent and the balance of a blending agent.

4. The cold and salt resistant concrete admixture according to claim 3, It is characterized in that The invention is composed of the following components by weight percentage: 38%-45% of water reducing agent, 32%-36% of antifreeze agent, 6%-8% of calcium carbonate, 5%-7% of polyvinyl alcohol, 6%-7.5% of modified nano-montmorillonite, 1%-2% of coupling agent and the balance of a blending agent.

5. The cold and salt resistant concrete admixture according to claim 4, It is characterized in that The invention is composed of the following components by weight percentage: 43% of water reducing agent, 33% of antifreeze agent, 7.5% of calcium carbonate, 6.8% of polyvinyl alcohol, 7.2% of modified nano-montmorillonite, 1.2% of coupling agent and the balance of a blending agent.

6. The cold and salt resistant concrete admixture according to any one of claims 1 to 5, It is characterized in that The water reducer is selected from at least one of a polycarboxylic acid water reducer, a naphthalene water reducer, a melamine water reducer, a lignin sulfonate water reducer, an aminosulfonate water reducer and a fatty acid water reducer.

7. The cold and salt resistant concrete admixture according to any one of claims 1 to 5, It is characterized in that The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate in the antifreeze is 3-6:2-4:1-1.

8.

8. The cold and salt resistant concrete admixture according to claim 7, It is characterized in that The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate in the antifreeze is 4.2-5:3-3.4:1.2-1.

4.

9. The cold-resistant and salt-resistant concrete admixture according to claim 8, It is characterized in that The mass ratio of diethylene glycol butyl ether acetate, hexaethyl phosphoramidite and copper 2-ethylhexanoate is 4.6:3.3:1.

3.

10. The cold-resistant and salt-resistant concrete admixture according to claim 1, It is characterized in that The preparation method of the modified nano-montmorillonite comprises the following steps: The nano-montmorillonite is pretreated with acid solution, taken out and washed with water to neutrality, then added into a solvent, and polyethylene glycol diglycidyl ether and glycerol are added to carry out modification reaction to obtain modified nano-montmorillonite.

11. The cold and salt resistant concrete admixture according to claim 10, It is 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%.

12. The cold-resistant and salt-resistant concrete admixture according to claim 11, It is characterized in that The added amount of the polyethylene glycol diglycidyl ether is 10%-15% of the mass of the nano-montmorillonite, and the added amount of the glycerol is 1%-5% of the mass of the nano-montmorillonite.

13. The cold and salt resistant concrete admixture according to claim 2, It is characterized in that The conditioning agent is selected from at least one of a defoamer, an air entraining agent and a thickener.

14. A method for preparing the cold-resistant and salt-resistant concrete admixture according to any one of claims 1 to 13, It is characterized in that The steps include: (1) The modified nano-montmorillonite is uniformly dispersed in water to obtain a mixed solution I; (2) mixing the water reducer, antifreeze agent, calcium carbonate, polyvinyl alcohol and water uniformly to obtain a mixed solution II; (3) mixing the mixed solution I obtained in step (1) with the mixed solution II obtained in step (2), subjecting the mixed solution to microwave-assisted heating treatment, and drying to obtain a cold-resistant and salt-resistant concrete admixture.

15. The preparation method according to claim 14, It is characterized in that In step (3), the microwave power of the microwave-assisted heating treatment is 300-600 W, the heating temperature is 45-60° C., and the time is 5-40 min.

16. The preparation method according to claim 14, It is characterized in that In step (3), a conditioning agent is added before the microwave-assisted heating treatment.

17. Application of cold-resistant and salt-resistant concrete admixtures in cold-resistant and salt-resistant concrete. It is characterized in that The cold-resistant and salt-resistant concrete admixture is the cold-resistant and salt-resistant concrete admixture described in any one of claims 1 to 13 or the cold-resistant and salt-resistant concrete admixture prepared by the preparation method described in any one of claims 14 to 16.

18. The use according to claim 17, It is 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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