A polycarboxylate water reducer specially used for annular concrete poles and a preparation method thereof

Abstract

The present invention provides a polycarboxylic acid water-reducing agent for annular concrete poles and a preparation method thereof, and belongs to the field of concrete admixtures. The water-reducing agent is prepared by two processes of mother liquor polymerization and auxiliary compounding of a polycarboxylic acid water-reducing agent mother liquor and a compounding auxiliary agent; the polycarboxylic acid water-reducing agent mother liquor is a polycarboxylic acid copolymer copolymerized by unsaturated alcohol-based polyethylene glycol ether macromonomer and β-(acryloxy) propionic acid, and its molecular weight distribution index Mw / Mn is less than 1.7, and the average molecular weight is 20000-80000; the molar ratio of unsaturated alcohol-based polyethylene glycol ether macromonomer to β-(acryloxy) propionic acid is 1:1-6. The compounding auxiliary agent contains iron-based element sulfate, carbonate or bicarbonate, and a composite air entraining agent. The water-reducing agent is used to prepare dry and hard concrete for annular poles, and the effect is better, it is easy to construct the material, the hardening strength is high, the demoulding time is short, and the prepared dry and hard concrete produces almost no concrete slurry during the centrifugal process, which is economical and environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the field of building materials, and in particular relates to a polycarboxylate water reducer special for annular concrete poles and a preparation method thereof. Background Art

[0002] Annular concrete poles are prefabricated concrete products made of sand, stone, cement, steel bars, etc. They are a type of cement prefabricated component commonly used in overhead power lines, lighting lines, and communication towers. In particular, the annular concrete poles used in overhead power transmission and transformation lines have a special status and importance. They are mainly used for distribution lines below 10KV and transmission lines and substation pillars of 35KV to 220KV. Annular concrete poles have many advantages such as good bearing capacity, low engineering cost, high concrete density, and long life. The construction of clean energy projects such as wind power generation and photovoltaic power generation will surely drive the further development of the annular concrete pole industry. Prefabricated wind power generation towers and concrete pillars for photovoltaic power generation may be another growth point for the pole industry, with huge market potential.

[0003] At present, the production of circular concrete poles mainly uses high-efficiency water reducers, mainly naphthalenesulfonic acid formaldehyde condensation polymers. The circular concrete poles prepared with this type of water reducer have good workability, low plastic viscosity, and are easy to construct and spread. However, there are also many problems, such as low water reduction rate, difficulty in preparing higher strength concrete, and high alkali content of naphthalenesulfonic acid formaldehyde condensation polymer water reducer, which has the hidden danger of concrete alkali aggregate reaction. In addition, the chloride ion content of this type of water reducer is high, which has the problem of steel corrosion and shortening the life of reinforced concrete. At the same time, a large amount of carcinogen formaldehyde and high-risk raw material concentrated sulfuric acid are used in the production process of naphthalenesulfonic acid formaldehyde condensation polymer water reducer, which has a great impact on the environment and will cause physical harm to personnel during use. At present, the production of circular concrete poles also attempts to use polycarboxylic acid water reducers, but this type of polycarboxylic acid water reducer is widely used in commercial concrete. There are many adaptability problems when applied to circular concrete poles, such as the prepared concrete is heavy and sticky, and the construction and spreading are laborious and inconvenient, which limits the application of polycarboxylic acid water reducers in circular concrete poles. In the production process of circular concrete poles, the plastic concrete currently prepared with naphthalenesulfonic acid formaldehyde condensation product water reducer will produce a lot of concrete slurry in the centrifugal process, which is not easy to handle and difficult to recycle. A solution is urgently needed. Therefore, it is very urgent to choose a higher performance and green environmentally friendly water reducer product and a new process for the production of circular concrete poles. Summary of the invention

[0004] The purpose of the present invention is to provide a polycarboxylic acid high-performance water-reducing agent for annular concrete poles, which can replace traditional naphthalenesulfonic acid formaldehyde condensation product high-efficiency water-reducing agents, etc. It can bring better water-reducing and dispersion effects, obtain higher early strength, and at the same time, dry hard concrete can be prepared to make annular concrete poles to obtain better construction material performance, greatly reduce concrete slurry, and the final precast concrete component product can obtain higher strength and better durability.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A polycarboxylate water-reducing agent for annular concrete poles is prepared by polymerizing a polycarboxylate water-reducing agent mother liquid and a compounding auxiliary agent through two processes: mother liquid polymerization and auxiliary agent compounding.

[0007] The polycarboxylate water-reducing agent mother liquor is composed of unsaturated alcohol-based polyethylene glycol ether macromonomer (see attached Figure 1 :Macromolecular structure diagram, attached Figure 2 : macromonomer gel chromatography GPC diagram) and β-(acryloyloxy) propionic acid copolymerized polycarboxylic acid copolymer, its molecular weight distribution index Mw / Mn <1.7, average molecular weight in the range of 20000 to 80000 (see attached Figure 3 : Gel chromatography (GPC) of polycarboxylic acid mother liquor); the unsaturated alcohol-based polyethylene glycol ether macromonomer is one or more of isobutylene polyethylene glycol HPEG, isoprene polyethylene glycol IPEG and ethyleneoxy polyethylene glycol EPEG (number average molecular weight Mn=5000), and the molar ratio of the unsaturated alcohol-based polyethylene glycol ether macromonomer to β-(acryloyloxy) propionic acid is 1:1-6.

[0008] The compound auxiliary agent contains iron element sulfate, carbonate or bicarbonate, composite air entraining agent and the like.

[0009] A preparation method of a polycarboxylic acid water-reducing agent for annular concrete poles comprises a polymerization process and a compounding process: (1) polymerization process: 1) preparing a base liquid: mixing and dissolving an unsaturated alcohol-based polyglycol ether macromonomer with a certain amount of deionized water to prepare a reaction base liquid; 2) preparing a drop liquid: adding a reducing agent, a chain transfer agent, and β-(acryloyloxy) propionic acid to deionized water in a stirring state to prepare a drop liquid, and homogenizing the drop liquid for use; 3) initiating polymerization: adding a co-catalyst and an oxidant to the base liquid in sequence, and after homogenizing, uniformly adding the drop liquid to a reaction system to carry out a polymerization reaction, the time being controlled within 15 to 180 minutes, and the reaction temperature being within 5° C. to 90° C.; 4) aging and discharging: after the drop liquid is added, adding a small amount of reducing agent (accounting for 5% to 10% of the reducing agent dosage in the drop liquid), continuing the reaction for 30 to 150 minutes, and then adding a sodium hydroxide aqueous solution to neutralize to pH=5 to 8 and a solid content of 30% to 60%, so as to obtain a polycarboxylic acid mother liquid.

[0010] The reducing agent is ascorbic acid and its sodium salt, isoascorbic acid and its sodium salt, lactose, thiourea dioxide, etc., and the amount used is 0.10% to 0.3% of the mass of the macromonomer;

[0011] The chain transfer agent is mercaptoacetic acid, mercaptopropionic acid and mercaptosuccinic acid, etc., and the amount used is 0.50% to 1.0% of the mass of the macromonomer;

[0012] The co-catalyst is p-toluenesulfonic acid, methanesulfonic acid or methylene disulfonic acid, etc., and the amount used is 0.05% to 1.5% of the mass of the macromonomer;

[0013] The oxidant is hydrogen peroxide or persulfate (sodium salt, potassium salt and ammonium salt), and the dosage is 0.60% to 1.2% of the mass of the macromonomer.

[0014] (2) Compounding process: first add compounding water into the compounding container; first add the reinforcing agent iron element sulfate under stirring; continue to add the polycarboxylic acid mother liquor under stirring; add the defoaming agent after homogenization; then add the inorganic colloid regulator for homogenization; finally add the composite air entraining agent for homogenization, and then obtain the polycarboxylic acid water reducer for the annular concrete pole;

[0015] Raw materials and their proportions by mass:

[0016] The reinforcing agent iron sulfate is one or more of iron sulfate, cobalt sulfate and nickel sulfate, and the added amount is 1.0% to 5.0%;

[0017] The polycarboxylic acid mother liquor is 20% to 60%;

[0018] The defoamer is an organosilicon defoamer and (or) polyether, and the addition amount is 0.1% to 1.0%;

[0019] The inorganic colloid regulator is sodium carbonate (potassium) or sodium bicarbonate (potassium), and the addition amount is 0.5% to 3%;

[0020] The air entraining agent is a compound of sodium dodecyl sulfate, polyether air entraining agent and triterpenoid saponin in a mass ratio of 1:1:1, and the added amount is 1.0% to 3.0%;

[0021] The water, the balance.

[0022] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0023] The polycarboxylic acid water-reducing agent for annular concrete poles provided by the present invention is synthesized by selecting ultra-long side chain polycarboxylic acid copolymers under the action of a co-catalyst. The obtained polymer has a small molecular weight distribution index and a high conversion rate, and has little effect on cement hydration reaction. Its comonomer β-(acryloyloxy) propionic acid is an esterified carboxylic acid, which not only takes into account the negative charge but also introduces an ester group. The esterified carboxylic acid also has a "secondary dispersion" effect after hydrolysis, which gives the concrete prepared with this type of water-reducing agent excellent workability. The ester functional group can also bring good cohesiveness and rheological properties, and is easy to construct and lay. The mother liquor of ultra-long side chain polycarboxylic acid water-reducing agent has a great promoting effect on the development of cement strength. On this basis, the inorganic reinforcing agent iron sulfate is used. Through complexation, the cement slurry can be well adsorbed to the stone surface, which can greatly improve the early strength of the concrete. At the same time, according to the principle of colloid chemistry, sodium carbonate (potassium) or sodium bicarbonate (potassium) is introduced into the water-reducing agent, and it is used to react with Ca in cement. 2+ The reaction of the same components to generate inorganic colloids can better adjust the state of concrete. Finally, the ternary composite air entraining agent and the amount far exceeding the normal amount and the appropriate amount of defoaming agent are used in the compounding to obtain the good working state of the concrete and the surface finish after hardening.

[0024] The polycarboxylic acid water-reducing agent product specially prepared for annular concrete poles can also be applied to small slump plastic concrete, especially to the centrifugal process of dry hard concrete without slump, with outstanding performance effect, fast strength development, short demoulding time, improved mold turnover efficiency, almost no concrete slurry is generated during the construction process, the production is green and environmentally friendly, the impact on the environment is small, and the application effect is satisfactory. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Molecular structures of three unsaturated alcohol-based polyethylene glycol ethers

[0026] Figure 2 GPC chart of 5000 molecular weight unsaturated alcohol-based polyethylene glycol ether macromonomer

[0027] Figure 3 Gel chromatography (GPC) of polycarboxylic acid mother solution DETAILED DESCRIPTION

[0028] The following specific cases are intended to more clearly express the specific implementation of the invention. The specific embodiments are some specific cases of the present invention and are not limitations of the present invention.

[0029] The embodiment of the present invention provides a polycarboxylate water-reducing agent product for annular concrete poles, which is composed of two steps: synthesizing a polycarboxylate water-reducing agent mother liquor and compounding functional auxiliary materials. Among them: the ternary composite air-entraining agent is compounded by sodium dodecyl sulfate, polyether air-entraining agent and triterpenoid saponin in a mass ratio of 1:1:1, and the polyether air-entraining agent used is Clariant Hostapur AE.

[0030] Embodiment 1:

[0031] Polymerization process: 180g of isobutylene polyethylene glycol (HPEG5000) with a number average molecular weight of 5000 is added to 180g of deionized water, and heated appropriately to fully dissolve to prepare a reaction base liquid; 0.4g of ascorbic acid, 0.8g of thioglycolic acid and 18g of β-(acryloyloxy) propionic acid are added to 65g of deionized water in sequence, mixed and stirred evenly, and prepared into a dropping liquid; the reaction temperature is controlled to be 25°C to 30°C, 0.3g of p-toluenesulfonic acid and 1.6g of 27.5% H2O2 are added to the reaction base liquid for 5min, and then the dropping liquid is dripped at a uniform speed, and the dropping is completed in 3h; after adding 0.02g of ascorbic acid and continuing the insulation reaction for 1.5h, a solution of 10g NaOH and 44g water is added, and stirred evenly to obtain a polycarboxylic acid mother liquor with a solid content of (40±1)%, and pH=7.4±0.5.

[0032] Compounding process: 536.0g of water and 10.8g of cobalt sulfate were stirred for 10 minutes, and then 431.2g of the polycarboxylic acid mother liquor synthesized in the above polymerization process was added and stirred for 30 minutes, and then 1.0g of silicone defoamer (Maitu 4701) was added and stirred for 10 minutes, and then 10.8g of sodium bicarbonate was added and stirred for 10 minutes, and finally 10.2g of ternary composite air entraining agent was added and stirred for 10 minutes to obtain a polycarboxylic acid water reducer for annular concrete poles.

[0033] Embodiment 2:

[0034] Polymerization process: 180g of isoprene polyethylene glycol (IPEG5000) with a number average molecular weight of 5000 is added to 100g of deionized water, and heated appropriately to fully dissolve to prepare a reaction base liquid; 0.4g of sodium isoascorbate, 0.6g of mercaptosuccinic acid and 12g of β-(acryloyloxy) propionic acid are added to 65g of deionized water in sequence, mixed and stirred evenly, and prepared into a dropping liquid; the reaction temperature is controlled to be 40°C to 50°C, 0.4g of methanesulfonic acid and 1.8g of 27.5% H2O2 are added to the reaction base liquid for 5min, and then the dropping liquid is dripped at a uniform speed, and the dropping is completed in 2h; 0.03g of sodium isoascorbate is added and the reaction is continued to be kept warm for 1h, and then a solution prepared by adding 6.0g of NaOH and 25g of water is added, and stirred evenly to obtain a polycarboxylic acid mother liquor with a solid content of (50±1)%, and a pH of 5.7±0.5.

[0035] Compounding process: 491.6g of water and 20.9g of ferric sulfate were stirred for 10 minutes, and then 470.8g of the polycarboxylic acid mother liquor synthesized in the above polymerization process was added and stirred for 30 minutes, and then 1.0g of silicone defoamer (Maitu 4701) was added and stirred for 10 minutes, and then 5.2g of potassium carbonate was added and stirred for 10 minutes, and finally 10.5g of ternary composite air entraining agent was added and stirred for 10 minutes to obtain a polycarboxylic acid water reducer for annular concrete poles.

[0036] Embodiment 3:

[0037] Polymerization process: 180g of ethyleneoxy polyethylene glycol (EPEG5000) with a number average molecular weight of 5000 is added to 150g of deionized water, and stirred to fully dissolve to prepare a reaction base liquid; 1.0g of lactose, 1.4g of mercaptopropionic acid and 13g of β-(acryloyloxy) propionic acid are added to 65g of deionized water in sequence, mixed and stirred evenly to prepare a dropping liquid; the reaction temperature is controlled to 5°C to 10°C, 0.1g of p-toluenesulfonic acid and 1.6g of ammonium persulfate are added to the reaction base liquid and homogenized for 5min, and then the dropping liquid is dripped at a uniform speed, and the dropping is completed in 0.5h; after adding 0.1g of lactose and continuing the heat preservation reaction for 1h, a solution prepared by 6.0g of NaOH and 200g of water is added, and stirred evenly to obtain a polycarboxylic acid mother liquor with a solid content of (32±1)%, and a pH of 6.7±0.5.

[0038] Compounding process: 537.2g of water and 13.9g of nickel sulfate were stirred for 10 minutes, and then 417.3g of the polycarboxylic acid mother liquor synthesized in the above polymerization process was added and stirred for 30 minutes, and then 1.6g of polyether defoamer (Evonik 4740) was added and stirred for 10 minutes, and then 8.6g of sodium carbonate was added and stirred for 10 minutes, and finally 21.4g of ternary composite air entraining agent was added and stirred for 10 minutes to obtain a polycarboxylic acid water reducer for annular concrete poles.

[0039] In the comparative example, a naphthalenesulfonic acid formaldehyde condensation polymer water reducer was used, and the sample of the above embodiment was applied to the preparation of C60 concrete for annular concrete poles (the mix ratio is shown in Table 1, PO 42.5 cement, S95 grade mineral powder), and the superiority of the invented product was evaluated by testing the three technical indicators of compressive strength, construction workability and surface finish.

[0040] Table 1: Mixing ratio of circular concrete pole C60 Unit: kg

[0041]

[0042] Table 2: Technical indicators of water reducing agent applied to C60 plastic concrete ring concrete pole

[0043]

[0044] Table 3: Technical indicators of water reducing agent applied to C60 dry hard concrete circular concrete pole

[0045]

[0046] It can be seen from Table 2 and Table 3 that the polycarboxylate water-reducing agent for annular concrete poles of the present invention has significant advantages, good workability of fresh concrete and easy distribution. After hardening, the concrete demoulding time of the polycarboxylate water-reducing agent for annular concrete poles is short, the compressive strength is higher, and the surface finish is good. The polycarboxylate water-reducing agent of the present invention performs better in dry hard concrete, and dry hard concrete can be preferentially selected to produce prefabricated annular concrete poles, thereby significantly reducing the residual concrete slurry and reducing the impact on the environment.

Claims

1. A polycarboxylate water-reducing agent for annular concrete poles, which is prepared by two processes of mother liquid polymerization and compounding of the additives from a polycarboxylate water-reducing agent mother liquid and a compounding additive; The polycarboxylate water-reducing agent mother liquor is a polycarboxylic acid copolymer copolymerized by unsaturated alcohol-based polyethylene glycol ether macromonomer and β-(acryloxy) propionic acid, and its molecular weight distribution index Mw / Mn is less than 1.7, and the average molecular weight is between 20000 and 80000; the unsaturated alcohol-based polyethylene glycol ether macromonomer is one or more of isobutylene polyethylene glycol HPEG, isoprene polyethylene glycol IPEG and ethyleneoxy polyethylene glycol EPEG with a number average molecular weight Mn=5000; the molar ratio of the unsaturated alcohol-based polyethylene glycol ether macromonomer to β-(acryloxy) propionic acid is 1:1 to 6; The compound auxiliary agent contains sulfate, carbonate or bicarbonate of iron series elements, composite air entraining agent and defoaming agent; The raw materials and their proportions are calculated by mass percentage: 1.0% to 5.0% of iron element sulfate; 20% to 60% of the polycarboxylic acid mother liquor; 0.1% to 1.0% of defoamer; 0.5% to 3% of carbonate or bicarbonate; 1.0% to 3.0% of composite air entraining agent; and water, the balance.

2. The method for preparing a polycarboxylate water reducer for annular concrete poles according to claim 1, characterized in that: The steps include: (1) Polymerization process: unsaturated alcohol-based polyethylene glycol ether macromonomer is mixed and dissolved with a certain amount of deionized water to prepare a reaction base liquid; reducing agent, chain transfer agent and β-(acryloyloxy) propionic acid are sequentially added to deionized water under stirring to prepare a drop solution, which is homogenized and set aside; co-catalyst and oxidant are sequentially added to the base liquid, and after homogenization, the drop solution is uniformly added to the reaction system for polymerization reaction, the time is controlled at 15 to 180 minutes, and the reaction temperature is 5°C to 90°C; after the drop solution is added, a small amount of reducing agent is added, and the reaction is continued for 30 to 150 minutes, and then sodium hydroxide aqueous solution is added to neutralize to pH = 5 to 8 and a solid content of 30% to 60%, thereby obtaining a polycarboxylic acid mother liquor; The amount of addition is based on the mass of the macromonomer: the amount of reducing agent in the dropwise solution is 0.10% ~ 0.3%, the amount of chain transfer agent is 0.50% ~ 1.0%; the amount of co-catalyst is 0.05% ~ 1.5%; the amount of oxidant is 0.60% ~ 1.2%; (2) Compounding process: first add compounding water into the compounding container; first add iron sulfate under stirring; continue to add polycarboxylic acid mother liquor under stirring; add defoamer after homogenization; then add carbonate or bicarbonate for homogenization; finally add composite air entraining agent for homogenization to obtain polycarboxylic acid water reducer for annular concrete poles; The raw materials and their proportions are calculated by mass percentage: 1.0% to 5.0% of iron element sulfate; 20% to 60% of the polycarboxylic acid mother liquor; 0.1% to 1.0% of defoamer; 0.5% to 3% of carbonate or bicarbonate; 1.0% to 3.0% of composite air entraining agent; and water, the balance.

3. The preparation method according to claim 2, characterized in that: In step (1), The reducing agent is one of ascorbic acid and its sodium salt, isoascorbic acid and its sodium salt, lactose and thiourea dioxide; The chain transfer agent is mercaptoacetic acid, mercaptopropionic acid or mercaptosuccinic acid; The co-catalyst is p-toluenesulfonic acid, methanesulfonic acid or methylene disulfonic acid; The oxidant is hydrogen peroxide or persulfate.

4. The preparation method according to claim 2, characterized in that: In step (2), The iron-based element sulfate is one or more of iron sulfate, cobalt sulfate and nickel sulfate; The defoamer is an organosilicon defoamer and / or a polyether defoamer; The carbonate or bicarbonate is sodium carbonate or sodium bicarbonate, potassium carbonate or potassium bicarbonate; The composite air-entraining agent is prepared by compounding sodium dodecyl sulfate, polyether air-entraining agent and triterpenoid saponin in a mass ratio of 1:1:1.

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