Preparation method of air entraining agent for roller compacted concrete

Abstract

The invention belongs to the field of concrete admixtures, and particularly relates to an air entraining agent for roller compacted concrete as well as a preparation method and application of the air entraining agent. In the air entraining agent for roller compacted concrete, the small organic molecule polyamine and the anionic surfactant can form a novel dynamic oligomeric surfactant, the novel dynamic oligomeric surfactant can have lower surface tension at low concentration, the surface activity is higher than that of a common surfactant, and bubbles are more easily introduced in the stirring and rolling processes; the thickening agent can obviously improve the viscosity of the solution, enables bubble film formation to be more stable and wall thickness toughness to be enhanced, also has a water retention effect, and can effectively reduce bubble breakage; other functional aids can customize interaction of liquid surface tension, intermolecular static electricity, hydrogen bonds and the like, and change steric hindrance and arrangement of molecules, so that the whole air entraining agent is more flexible and effective, and has pertinence and adaptability. The preparation technology of the air entraining agent for roller compacted concrete is simple, large-scale production is easy to achieve, and good social benefits and economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the field of concrete admixtures, and in particular relates to an air entraining agent for roller compacted concrete and a preparation method and application thereof. Background Art

[0002] Most of my country's remaining hydropower resources are distributed in the west. Most of the regions have complex terrain, large climate changes, and frequent severe weather, which increases the difficulty of developing hydropower resources. Roller-compacted concrete dams have the advantages of rapid construction and low cost, so they have become one of the most commonly used dam types in complex environments such as high cold and high altitude. However, due to the small amount of adhesive used in roller-compacted concrete, the relatively dry and hard state of the mixture, and the high amount of fly ash, it is difficult to introduce bubbles into the concrete, which makes the frost resistance and durability of the hardened concrete seriously insufficient.

[0003] So far, the research on air-entraining agents for concrete still faces technical bottlenecks such as difficulty in air entrainment and poor foam stability. At present, the commonly used air-entraining agents mainly include rosin air-entraining agents, lignin sulfonic acid air-entraining agents, alkylbenzene sulfonate air-entraining agents, saponin air-entraining agents, polyether air-entraining agents, etc. Although there are a variety of air-entraining agents, they all have certain defects. For example, the quality control of rosin air-entraining agents is poor and the air-entraining effect is unstable; the dosage of lignin sulfonic acid air-entraining agents is large and the bubble structure is unstable; the stability of bubbles introduced by alkylbenzene sulfonate air-entraining agents is also poor; polyether air-entraining agents have a large molecular weight and slow migration speed, and are not suitable for dry and hard concrete. Moreover, although there are more and more concrete air-entraining agent products on the market, there are very few that are suitable for rolled concrete, especially the above-mentioned types of air-entraining agents usually need to be added in a large proportion to introduce a certain amount of bubbles, and due to the problem of dry and hard concrete, the bubbles are very easy to break and difficult to maintain stably, and the foaming and foam stabilization properties are greatly weakened, so that the concrete loses its due antifreeze properties.

[0004] In order to solve the above problems, Chinese patent application CN110002783A provides a high-efficiency air-entraining agent for roller compacted concrete and a preparation method thereof, which uses ethanol as a solvent, and under low-temperature heating conditions, reacts long-chain alkyl primary amines, 1,4-dibromobutane, formaldehyde, formic acid, and 3-chloro-2-hydroxypropane sulfonate sodium to generate a monomer or mixture of alkyl (twelve, fourteen or sixteen) sulfonate gemini surfactants. The surfactant prepared by this method has a good molecular structure, has a lower surface tension than traditional surfactants under the same molar concentration, and is easier to introduce bubbles. However, the preparation process is relatively complicated and the use cost is high, which is not conducive to large-scale promotion and application. In addition, Chinese patent CN112624660B (China Communications Wuhan Port Institute) discloses an air entraining agent for antifreeze concrete in high altitude areas and its preparation method, which is prepared by mixing fatty alcohol polyoxyethylene ether sodium sulfate (15-20%), sodium lauryl sulfate (8-10%), dodecyl betaine (1-3%), cocamidopropyl betaine (1-3%), cocamidopropyl hydroxysulfobetaine (2-4%), cocamidopropyl amine oxide (1-3%), modified silicone resin polyether microemulsion (1-3%), and polycarboxylic acid air entraining agent (60-65%) at room temperature. This patent uses synthesis and compounding technology to exert the synergistic effect between components, so that the air entraining agent has excellent foaming and foam stability. However, the method uses many types of raw materials and a complex synthesis process, resulting in excessively high use costs, which is not conducive to popularization and application.

[0005] Therefore, it is urgent to identify the key points to improve the performance of air-entraining agents from the molecular level according to the characteristics of RCC, and to develop an air-entraining agent with high foaming and high foam stability specifically for RCC. Summary of the invention

[0006] The main technical problem solved by the present invention is to provide an air-entraining agent for roller compacted concrete. In order to solve the problems of difficulty in air entrainment in roller compacted concrete, poor bubble stability, and high dosage of air-entraining agent, a dynamic oligomeric surfactant is formed by selecting functional small molecules with flexible structures, and compounding them with thickening and viscosity-increasing components to improve the air entraining efficiency and foam stabilizing performance of the air-entraining agent. Compared with conventional air-entraining agents, the dosage of air-entraining agents used in roller compacted concrete is significantly reduced.

[0007] Secondly, the present invention provides a method for preparing an air entraining agent for roller compacted concrete, which has simple process, convenient operation, easy large-scale production and good social and economic benefits.

[0008] Again, the present invention provides an application of an air-entraining agent for roller compacted concrete in the preparation of roller compacted concrete.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] An air entraining agent for roller compacted concrete, the raw materials for preparation include, by weight: 20-50 parts of organic small molecule polyamine, 100 parts of anionic surfactant, 5-25 parts of thickener, and 10-30 parts of other functional additives;

[0011] The organic small molecule polyamine is selected from one or more of 1,3-propylenediamine, bis(2-aminoethyl) ether, bis(3-aminopropyl) ether, spermine, spermidine, diethylenetriamine, and triethylenetetramine;

[0012] The anionic surfactant is selected from one or more of carboxylate anionic surfactants, sulfonate anionic surfactants and sulfate anionic surfactants.

[0013] Specifically, the organic small molecule polyamine selected by the present invention has good water solubility because its molecular weight is small and has more amine groups, can form a large number of hydrogen bonds. The pKa of organic small molecule polyamine is mostly between 9.5-11.0. In aqueous solution, the protonation degree of polyamine molecules can be changed by adjusting the pH value, thereby changing the electrostatic force and van der Waals force between it and other molecules. In addition, due to the nature of its organic matter, when a new interface is formed, it is more inclined to migrate to the interface quickly, and drives the rapid migration of anionic surfactants, which can quickly reduce interfacial tension. The molecular structural formula of organic small molecule polyamine is shown below.

[0014]

[0015] As a preferred embodiment of the present invention, the carboxylate anionic surfactant is selected from one or two of sodium 2-hexyldecanoate (CAS: 536-37-8) and sodium 2,2,4,8,10,10-hexamethylundecane-5-carboxylate.

[0016] Specifically, the preparation method of sodium 2,2,4,8,10,10-hexamethylundecane-5-carboxylate is as follows: weigh a certain amount of isostearic acid (=2,2,4,8,10,10-hexamethylundecane-5-carboxylic acid) (CAS: 54680-48-7), dissolve it in ethanol, and then add sodium hydroxide with a molar ratio of 1:1.1 to react. For example, weigh a certain amount of isostearic acid, dissolve it in ethanol and transfer it to a three-necked flask, then add a sodium hydroxide solution with a molar ratio of 1:1.1, add a magnetic bar and connect a condenser reflux tube, heat it in a water bath or an oil bath, stir it at a magnetic bar speed of 300-400rpm, react at 80°C for 4h, stop heating, cool to room temperature, then use a rotary evaporator to spin dry the solvent, and then transfer it to a 40°C vacuum drying oven for drying for 8h to obtain solid sodium isostearate.

[0017] As a preferred embodiment of the present invention, the sulfonate anionic surfactant is selected from one or more of sodium dioctyl sulfosuccinate, sodium C10-C14 alkyl sulfonate, and sodium C10-C14 alkylbenzene sulfonate.

[0018] As a preferred embodiment of the present invention, the sulfate ester salt anionic surfactant is selected from one or more of C10-C14 alkyl sodium sulfates.

[0019] Specifically, the anionic surfactants selected by the present invention include sodium 2-hexyldecanoate, sodium 2,2,4,8,10,10-hexamethylundecane-5-carboxylate and sodium diisooctyl sulfosuccinate, which are single-head double-tail anionic surfactants. In the single-molecule state, they present a triangular structure of "small head and large tail" ("head" refers to the anionic head group, and "tail" refers to the hydrophobic alkyl chain). When distributed at the interface, they can better form spatial structural complementarity with sulfonate anionic surfactants, thereby improving the orderliness and compactness of the molecular arrangement at the interface. At the same time, the structure of the double-tail chain makes it have a lower critical micelle concentration and equilibrium surface tension. Alkyl sodium sulfonate (such as sodium dodecyl sulfonate), sodium alkylbenzene sulfonate (such as sodium dodecylbenzene sulfonate), and sodium alkyl sulfate (sodium dodecyl sulfate) are all commonly used foaming surfactants. Unlike rosin-based air-entraining agents, polyether-based air-entraining agents, etc., they have a smaller molecular weight, a faster molecular migration speed to the interface, a more efficient ability to reduce surface tension and form bubbles, and have the characteristics of low cost and good foam stability. The molecular structure of anionic surfactants is shown below.

[0020]

[0021] The present invention uses organic small molecule polyamine and anionic surfactant as the main parts of the air entraining agent. First, both are low molecular weight compounds, and have a faster molecular migration speed in aqueous solution. In the dry and hard concrete such as rolled concrete, they can migrate faster to the solid-liquid and gas-liquid interfaces, thereby quickly forming bubbles. Second, the two can self-assemble to form a new type of dynamic oligomeric surfactant, which can shorten the distance between surfactant molecules through the connecting group to suppress electrostatic repulsion, such as Figure 1 As shown. The experimental results show that oligomeric surfactants have high surface activity at extremely low concentrations, can significantly reduce the surface tension of aqueous solutions, and have stronger foaming performance. In addition, by adjusting the pH value (for example, using dilute nitric acid or sodium hydroxide solution), the interaction and matching degree between organic small molecule polyamines and anionic surfactants can be adjusted, thereby changing the oligomerization degree and surface activity, better matching other components and adapting to mixing materials and environments.

[0022] As a preferred embodiment of the present invention, the thickener is selected from one or more of glycerol, guar gum, xanthan gum, carboxymethyl cellulose, hydroxyethyl cellulose and hyaluronic acid.

[0023] Specifically, among the thickeners selected in the present invention, glycerol is a commonly used small molecule thickener, and its polyhydroxy structure can form a large number of hydrogen bond couplings in water, thereby changing the viscosity and rheology of the aqueous solution; guar gum is an extract of guar beans, has good dispersibility and solubility in cold water, is not easy to agglomerate, and has good compatibility with anionic surfactants, zwitterionic surfactants, etc., and in addition to viscosity and thickening, can also improve the fullness and stability of the foam; xanthan gum is a polysaccharide polymer compound generated by fungal fermentation, has good compatibility with a variety of salts, combines thickening and stabilization, and is the most superior biological glue; carboxymethyl cellulose and hydroxyethyl cellulose both belong to cellulose ethers, have good water solubility and compatibility, can change the rheology of the solution, and have good thickening, water retention, and film-forming effects, and can improve the density of the bubble liquid film; hyaluronic acid is a large molecular polysaccharide, has strong viscoelasticity and water retention, can prolong the liquid film drainage time, enhance the elasticity and toughness of the liquid film, and thus improve the stability of the bubble. The thickener (also referred to as a viscosity-enhancing, thickening and stabilizing component) selected in the present invention has good water solubility and water retention in the surfactant solution, has good viscosity-enhancing, thickening and stabilizing effects, and is environmentally friendly.

[0024] As a preferred embodiment of the present invention, the other functional additives are selected from one or more of lauryl alcohol, lauryl glucoside (CAS: 110615-47-9), cocoyl propyl dimethyl amine oxide (CAS: 85408-49-7), cocamidopropyl betaine (CAS: 61789-40-0), sodium myristoyl glutamate (CAS: 38517-37-2), sodium lauroyl sarcosinate (CAS: 137-16-6), and sodium lauroyl glutamate (CAS: 29923-31-7).

[0025] Specifically, the dodecanol in the other functional additives selected by the present invention is an organic compound, which is insoluble in water. However, in the presence of a surfactant, its solubility in water can be improved, and a very small amount of dodecanol can effectively reduce the surface tension of the surfactant solution and improve the foaming property; lauryl glucoside is an alkyl glycoside nonionic surfactant, which has good hard water resistance, is easily soluble in water, has strong wetting power, produces rich and delicate foam, and has a certain thickening effect, and is a green surfactant with comprehensive performance; cocoyl dimethyl amine oxide and cocoyl betaine are amphoteric surfactants, and their aqueous solutions are cationic under acidic conditions and nonionic under alkaline conditions. The lengths of the hydrophobic tail chains in their components are different, and they can be efficiently arranged according to the intermolecular forces, and have good surface activity; sodium myristoyl glutamate, sodium lauroyl sarcosinate, and sodium lauroyl glutamate are amino acid surfactants, which have strong wetting and foaming abilities, can better match other surfactants, and improve foaming synergy. The types of other functional additives selected in the present invention are various, and they can be selectively added according to the main part of the air-entraining agent, the type of concrete, and the mixing materials. They can be customized to regulate the surface tension of the liquid, the interactions such as electrostatic and hydrogen bonds between molecules, and change the spatial steric hindrance and arrangement of molecules, so that the air-entraining agent as a whole is more flexible and effective, with targetedness and adaptability, and assists in achieving the foaming and foam stabilizing effects.

[0026] As a preferred embodiment of the present invention, the air entraining agent for roller compacted concrete is in the form of an aqueous solution with a solid content of 5wt%-35wt%, preferably 15wt%-30wt%.

[0027] A method for preparing an air entraining agent for roller compacted concrete comprises the following steps:

[0028] Add organic small molecule polyamine into water to dissolve, and adjust the pH value of the solution to 7-8;

[0029] Anionic surfactants, other functional additives and thickeners are added and mixed to obtain an air entraining agent for roller compacted concrete.

[0030] As a preferred embodiment of the present invention, the anionic surfactant, other functional additives and thickener are added in sequence, and the latter component is added after the former component is completely dissolved.

[0031] As a preferred embodiment of the present invention, the thickener is first dissolved in water before being added until the solution is transparent and uniform.

[0032] As a preferred embodiment of the present invention, after the mixing, a proper amount of water can be added to adjust the air entraining agent for roller compacted concrete to a set solid content. After adding water and mixing, take out and seal for storage.

[0033] Specifically, the method for preparing the air entraining agent for roller compacted concrete comprises the following steps:

[0034] (1) Accurately weigh each component according to weight;

[0035] (2) adding an organic small molecule polyamine to water, stirring and dissolving it, and adjusting the pH value of the solution to 7-8 to obtain solution A;

[0036] Add the thickener into water and stir to dissolve to obtain solution B;

[0037] (3) adding anionic surfactant to solution A and stirring to dissolve, and then adding other functional additives and stirring to dissolve, to obtain solution C;

[0038] Alternatively, anionic surfactants and other functional additives are added to solution A and stirred to dissolve to obtain solution C;

[0039] (4) Solution B and Solution C are mixed, water is added and stirred to obtain an air entraining agent for roller compacted concrete.

[0040] The invention discloses an application of an air entraining agent for roller compacted concrete in the preparation of roller compacted concrete.

[0041] As a preferred embodiment of the present invention, the amount of the air entraining agent for roller compacted concrete in the roller compacted concrete is 0.03‰-0.3‰ of the mass of the cementitious material. The specific amount can be determined through experiments according to the required air content in the concrete.

[0042] As a preferred embodiment of the present invention, the air entraining agent for roller compacted concrete is directly added to the concrete together with other admixtures, or is first dissolved in water and then added to the concrete.

[0043] Beneficial effects of the present invention:

[0044] The present invention provides an air entraining agent for roller compacted concrete, the main body of the air entraining agent is a new type of dynamic oligomeric surfactant, which is formed by organic small molecule polyamine and anionic surfactant, which can reduce the electrostatic repulsion of anionic surfactant through small molecule polyamine, improve the density of surfactant arrangement at the interface, thereby obtaining higher surface activity, foaming ability and foam stabilization ability are better than ordinary surfactants, and are more suitable for roller compacted concrete. The single-headed double-tailed anionic surfactant selected by the present invention can complement the single-chain (straight-chain) surfactant (preferably single-chain large-headed surfactant, such as sodium dodecyl sulfate, sodium dodecyl sulfonate, etc.) in spatial structure, improve the hydrophobic interaction between surfactant tail chains, and make the hydrophobic tail chains more closely arranged, and the ability to reduce surface tension is stronger. In addition, the thickener selected by the present invention is highly environmentally friendly, has good water solubility, water retention and stability in surfactant solutions, etc., can change the rheology of the solution, improve the density of the liquid film, extend the liquid film drainage time, enhance the elasticity and toughness of the liquid film, thereby improving the stability of the bubble. The present invention selects various types of molecules such as nonionic surfactants, amphoteric surfactants, amino acid surfactants and dodecanol as functional additives, which can effectively alleviate the electrostatic repulsion between surfactants, improve the adaptability to sand and gravel materials, reduce adsorption losses, and improve the overall stability of the air entraining agent.

[0045] The present invention provides a method for preparing an air entraining agent for roller compacted concrete. By adjusting the pH value of the solution, the interaction force and matching degree between the organic small molecule polyamine and the anionic surfactant can be adjusted, the oligomerization degree and the surface activity can be changed, and other components can be better matched and adapted to the mixing materials and the environment. The method has a simple preparation process, is easy to realize large-scale production, and has good application potential and high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the structure of dynamic surfactants with different degrees of polymerization.

[0047] In order to more clearly illustrate the technical solution to be protected by the present invention, the above drawings in the embodiments are briefly introduced. It should be understood that the above drawings should not be regarded as any limitation on the protection scope of the present invention. For ordinary technicians in this field, other related drawings can also be obtained based on these drawings without paying creative work. DETAILED DESCRIPTION

[0048] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments and comparative examples. Those skilled in the art should understand that the following embodiments and comparative examples are only used to illustrate the technical scheme and technical effects of the present invention and should not be regarded as any limitation on the scope of protection of the present invention. Based on the following embodiments, other technical schemes obtained by ordinary technicians in the field without paying creative work, such as technical schemes obtained after modification, deformation or simple replacement, all belong to the scope of protection of the present invention. In the absence of conflict, the technical features in different embodiments can be combined and replaced with each other.

[0049] Example 1

[0050] This embodiment provides an air entraining agent for roller compacted concrete, and the raw materials for preparation are as follows in parts by weight:

[0051] Solute:

[0052] Organic small molecule polyamine: 15 parts of diethylenetriamine, 10 parts of 1,3-propylenediamine;

[0053] Anionic surfactant: 70 parts of sodium lauryl sulfate, 30 parts of sodium diisooctyl sulfosuccinate;

[0054] Thickener: 8 parts of glycerol, 4 parts of guar gum;

[0055] Other functional additives: 1 part of lauryl alcohol, 8 parts of cocamidopropyl betaine, 4 parts of lauryl glucoside;

[0056] Solvent:

[0057] 500 parts of deionized water.

[0058] This embodiment provides a method for preparing an air entraining agent for roller compacted concrete, comprising the following steps:

[0059] In parts by weight, 15 parts of diethylenetriamine, 10 parts of 1,3-propylenediamine, 70 parts of sodium lauryl sulfate, 30 parts of sodium diisooctyl sulfosuccinate, 8 parts of glycerol, 4 parts of guar gum, 1 part of dodecanol, 8 parts of cocamidopropyl betaine and 4 parts of lauryl glucoside and 500 parts of deionized water were weighed.

[0060] Add diethylenetriamine, 1,3-propylenediamine and half of the deionized water into a beaker, turn on the magnetic stirrer (350 rpm), adjust the pH value of the solution to 7 with dilute nitric acid, then add sodium dodecyl sulfate, sodium diethylhexyl sulfosuccinate, dodecanol, cocamidopropyl betaine and lauryl glucoside in sequence and continue stirring to dissolve; stir and dissolve glycerol, guar gum and the remaining water in another beaker at high speed until the solution is transparent and uniform; then combine the two solutions, take them out after stirring for a period of time, and obtain an air entraining agent for roller compacted concrete, which is sealed and stored for later use.

[0061] Example 2

[0062] This embodiment provides an air entraining agent for roller compacted concrete, and the raw materials for preparation are as follows in parts by weight:

[0063] Solute:

[0064] Organic small molecule polyamine: 20 parts of 1,3-propylenediamine, 10 parts of bis(2-aminoethyl) ether;

[0065] Anionic surfactant: 60 parts of sodium dodecyl sulfate, 20 parts of sodium diisooctyl sulfosuccinate, 20 parts of sodium 2-hexyldecanoate;

[0066] Thickener: 5 parts of glycerol, 5 parts of hydroxyethyl cellulose, 2 parts of xanthan gum;

[0067] Other functional additives: 2 parts of lauryl alcohol, 7 parts of cocoyl propyl dimethyl amine oxide, 5 parts of sodium lauroyl glutamate;

[0068] Solvent:

[0069] 500 parts of deionized water.

[0070] This embodiment provides a method for preparing an air entraining agent for roller compacted concrete, comprising the following steps:

[0071] In parts by weight, weigh 20 parts of 1,3-propylenediamine, 10 parts of bis(2-aminoethyl) ether, 60 parts of sodium dodecyl sulfate, 20 parts of sodium diisooctyl sulfosuccinate, 20 parts of sodium 2-hexyldecanoate, 5 parts of glycerol, 5 parts of hydroxyethyl cellulose, 2 parts of xanthan gum, 2 parts of dodecanol, 7 parts of cocoyl propyl dimethyl amine oxide and 5 parts of sodium lauroyl glutamate, and 500 parts of deionized water.

[0072] Add 1,3-propylenediamine, bis(2-aminoethyl) ether and half of the deionized water into a beaker, turn on the magnetic stirrer (350 rpm), adjust the pH value of the solution to 7 with dilute nitric acid, then add sodium dodecyl sulfate, sodium dioctyl sulfosuccinate, sodium 2-hexyldecanoate, dodecanol, cocoyl propyl dimethylamine oxide and sodium lauroyl glutamate in sequence and continue stirring to dissolve; stir and dissolve glycerol, hydroxyethyl cellulose, xanthan gum and the remaining water in another beaker at high speed until the solution is transparent and uniform; then combine the two solutions, take them out after stirring for a period of time, and obtain an air entraining agent for roller compacted concrete, which is sealed and stored for later use.

[0073] Example 3

[0074] This embodiment provides an air entraining agent for roller compacted concrete, and the raw materials for preparation are as follows in parts by weight:

[0075] Solute:

[0076] Organic small molecule polyamine: 20 parts of spermidine;

[0077] Anionic surfactant: 50 parts of sodium dodecylbenzene sulfonate, 50 parts of sodium dodecyl sulfate;

[0078] Thickener: 3 parts of glycerol, 6 parts of carboxymethyl cellulose, 1 part of hyaluronic acid;

[0079] Other functional additives: 10 parts of cocamidopropyl betaine, 5 parts of sodium lauroyl sarcosinate, 2 parts of lauryl glucoside;

[0080] Solvent:

[0081] 500 parts of deionized water.

[0082] This embodiment provides a method for preparing an air entraining agent for roller compacted concrete, comprising the following steps:

[0083] In parts by weight, weigh 20 parts of spermidine, 50 parts of sodium dodecylbenzene sulfonate, 50 parts of sodium lauryl sulfate, 3 parts of glycerol, 6 parts of carboxymethyl cellulose, 1 part of hyaluronic acid, 10 parts of cocamidopropyl betaine, 5 parts of sodium lauroyl sarcosinate, 2 parts of lauryl glucoside, and 500 parts of deionized water.

[0084] Spermidine and half of the deionized water are added into a beaker, and a magnetic stirrer (350 rpm) is turned on. The pH value of the solution is adjusted to 8 with dilute nitric acid, and then sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, cocamidopropyl betaine, sodium lauroyl sarcosinate, and lauryl glucoside are added in sequence and stirred to dissolve. Glycerol, carboxymethyl cellulose, hyaluronic acid and the remaining water are stirred at high speed in another beaker to dissolve until the solution is transparent and uniform. The two solutions are then combined, stirred for a period of time, and then taken out to obtain an air entraining agent for roller compacted concrete, which is sealed and stored for later use.

[0085] Example 4

[0086] This embodiment provides an air entraining agent for roller compacted concrete, and the raw materials for preparation are as follows in parts by weight:

[0087] Solute:

[0088] Organic small molecule polyamine: 30 parts of diethylenetriamine;

[0089] Anionic surfactant: 100 parts of sodium lauryl sulfate;

[0090] Thickener: guar gum 10 parts;

[0091] Other functional additives: 30 parts of cocamidopropyl betaine;

[0092] Solvent:

[0093] 350 parts of deionized water.

[0094] This embodiment provides a method for preparing an air entraining agent for roller compacted concrete, comprising the following steps:

[0095] In parts by weight, weigh 30 parts of diethylenetriamine, 100 parts of sodium lauryl sulfate, 10 parts of guar gum, 30 parts of cocamidopropyl betaine, and 350 parts of deionized water.

[0096] Add diethylenetriamine and half of the deionized water into a beaker, turn on the magnetic stirrer (350 rpm), adjust the pH value of the solution to 8 with dilute nitric acid, then add sodium lauryl sulfate and cocamidopropyl betaine in sequence and continue to stir and dissolve; stir and dissolve guar gum and the remaining water in another beaker at high speed until the solution is transparent and uniform; then combine the two solutions, take them out after stirring for a period of time, and obtain an air entraining agent for roller compacted concrete, which is sealed and stored for later use.

[0097] In other embodiments of the present invention, the raw materials for preparing the air entraining agent for roller compacted concrete are shown in Table 1, and the preparation methods are the same as those in Example 1.

[0098] Table 1 Raw material composition of air entraining agent for roller compacted concrete in each embodiment

[0099]

[0100]

[0101] Comparative Example 1

[0102] In this comparative example, sodium dodecyl sulfate (K12) was dissolved to prepare an aqueous solution with the same solid content of the air-entraining agent as that in Example 1, and the aqueous solution was sealed and stored for later use.

[0103] Comparative Example 2

[0104] In this comparative example, a commercially available rosin air-entraining agent was selected and diluted to prepare an aqueous solution having the same solid content as the air-entraining agent in Example 1, and the aqueous solution was sealed and stored for later use.

[0105] Experimental example

[0106] 1. Foaming and foam stability test

[0107] The air-entraining agents prepared in the above examples and comparative examples were diluted to 0.1‰, and 50 mL of samples were taken respectively. The foaming and foam stability tests were carried out using a special bubbling device with a special microporous air-inflating stone that can control the flow rate and read the foam volume. Under the condition of a flow rate of 0.1 L / min, the time (t 20mL ), the time taken to consume 20mL of foam (t -20mL), and the volume of foam generated within 1 min (V 1min ) and other parameters, and the results are shown in Table 2.

[0108] Table 2 Foamability and foam stability test results of air entraining agents prepared in Examples and Comparative Examples

[0109] Air Entraining Agent <![CDATA[V 1min (mL)]]> <![CDATA[t 20mL (s)]]> <![CDATA[t -20mL (min)]]> Bubble fineness Example 1 167 6s 22 Uniform small bubbles Example 2 172 5s 21 Uniform small bubbles Example 3 163 6s 16 Uniform small bubbles Example 4 165 6s 18 Uniform small bubbles Example 5 152 8s 18 Uniform small bubbles Comparative Example 1 161 7s 10 The bubbles are slightly larger and have a large hole in the middle Comparative Example 2 143 9s 12 Slightly larger bubbles

[0110] It can be seen from Table 2 that the foaming property and foam stability of the air-entraining agent prepared in the embodiment of the present invention are better than those of rosin and K12 air-entraining agents, and the foam is more delicate.

[0111] 2. Performance testing

[0112] Limestone artificial fine aggregate with a fineness modulus of 2.72, an average particle size of 0.43 mm, and a stone powder content of 21% and limestone coarse aggregate with a particle size range of 5-20 mm and 20-40 mm were used for mixing secondary RCC. The cement used was P.MH 42.5 cement produced by Weidun Cement Group Co., Ltd., the admixture was Class I fly ash provided by Hejin Power Plant, and the water reducer was naphthalene-based high-efficiency water reducer (slow-setting type). The mix parameters are shown in Table 3.

[0113] Table 3 RCC mix parameters

[0114]

[0115] The air-entraining agents prepared in the embodiment and the comparative example were respectively used for performance testing, and the results of working degree, initial air content, 1h air content and 1h air content loss rate are shown in Table 4.

[0116] Table 4 Performance test results

[0117] Air Entraining Agent Working degree VC(s) Initial gas content (%) Gas content in 1h (%) 1h gas content loss rate (%) Example 1 2.9 5.6 5.1 8.9 Example 2 3.3 5.1 4.8 5.9 Example 3 3.8 4.9 4.7 4.1 Example 4 3.5 5.5 4.9 10.9 Example 5 3.6 5.2 4.6 11.5 Comparative Example 1 4.1 4.7 3.4 27.6 Comparative Example 2 3.5 5.0 4.1 18.0

[0118] As can be seen from Table 4, the air entraining agent prepared in the embodiment is similar to the commercially available air entraining agent in terms of workability, with a slight advantage, but has a greater advantage in terms of air content and warning loss, indicating that it is more suitable for RCC.

[0119] Although the technical scheme and technical effects of the present invention have been described in detail above by means of general description, specific embodiments and comparative examples, for those skilled in the art, any modification, replacement or improvement made without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing an air entraining agent for roller compacted concrete, characterized in that: The raw materials for preparing the air entraining agent for roller compacted concrete include, by weight: 20-50 parts of organic small molecule polyamine, 100 parts of anionic surfactant, 5-25 parts of thickener, and 10-30 parts of other functional additives; The method for preparing the air entraining agent for roller compacted concrete comprises the following steps: Add organic small molecule polyamine into water to dissolve, and adjust the pH value of the solution to 7-8; adding anionic surfactant, other functional additives and thickener, and mixing well to obtain air entraining agent for roller compacted concrete; The organic small molecule polyamine is selected from one or more of 1,3-propylenediamine, bis(2-aminoethyl) ether, bis(3-aminopropyl) ether, spermine, spermidine, diethylenetriamine, and triethylenetetramine; The anionic surfactant is selected from one or more of carboxylate anionic surfactants, sulfonate anionic surfactants and sulfate anionic surfactants.

2. The preparation method according to claim 1, characterized in that: The carboxylate anionic surfactant is selected from one or two of sodium 2-hexyldecanoate and sodium 2,2,4,8,10,10-hexamethylundecane-5-carboxylate.

3. The preparation method according to claim 1, characterized in that: The sulfonate anionic surfactant is selected from one or more of sodium dioctyl sulfosuccinate, sodium C10-C14 alkyl sulfonate, and sodium C10-C14 alkylbenzene sulfonate.

4. The preparation method according to claim 1, characterized in that: The sulfate ester salt anionic surfactant is selected from one or more of C10-C14 alkyl sodium sulfates.

5. The preparation method according to claim 1, characterized in that: The thickener is selected from one or more of glycerol, guar gum, xanthan gum, carboxymethyl cellulose, hydroxyethyl cellulose and hyaluronic acid.

6. The preparation method according to claim 1, characterized in that: The other functional auxiliary agents are selected from one or more of lauryl alcohol, lauryl glucoside, cocoyl propyl dimethyl amine oxide, cocamidopropyl betaine, sodium myristoyl glutamate, sodium lauroyl sarcosinate, and sodium lauroyl glutamate.

7. The preparation method according to claim 1, characterized in that: The air entraining agent for roller compacted concrete is in the form of an aqueous solution with a solid content of 5wt%-35wt%.

8. The preparation method according to claim 1, characterized in that: The anionic surfactant, other functional additives and thickener are added in sequence, and the latter component is added after the former component is completely dissolved; And / or, the thickener is dissolved in water before being added.

9. The preparation method according to claim 7, characterized in that: After the mixing, a proper amount of water is added to adjust the air entraining agent for the roller compacted concrete to a set solid content.

10. The preparation method according to claim 8, characterized in that: The following steps are involved: (1) Accurately weigh each component according to weight; (2) adding an organic small molecule polyamine to water, stirring and dissolving it, and adjusting the pH value of the solution to 7-8 to obtain solution A; Add the thickener into water and stir to dissolve to obtain solution B; (3) adding anionic surfactant to solution A and stirring to dissolve, and then adding other functional additives and stirring to dissolve, to obtain solution C; Alternatively, anionic surfactants and other functional additives are added to solution A and stirred to dissolve to obtain solution C; (4) Solution B and Solution C are mixed, water is added and stirred to obtain an air entraining agent for roller compacted concrete.

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