CN111217970A - Modified starch concrete air entraining agent and preparation method thereof - Google Patents
Modified starch concrete air entraining agent and preparation method thereof Download PDFInfo
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- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
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- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
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Abstract
The invention discloses a modified starch concrete air entraining agent and a preparation method thereof, which comprises the steps of firstly utilizing high-temperature amylase and hydrogen peroxide to carry out enzymatic degradation and oxidative degradation on starch in sequence to obtain degraded starch, then adopting 2, 4-dihydroxy benzene sulfonic acid, 3-aminobenzene sulfonic acid and 1, 2-dibutyl naphthalene-6-sodium sulfonate to carry out graft modification on the degraded starch under the catalysis of horseradish peroxidase, and then carrying out graft copolymerization modification on the degraded starch by using methyl allyl polyoxyethylene ether under the initiation of ammonium persulfate to prepare the modified starch concrete air entraining agent. The modified starch air entraining agent prepared by the invention structurally has the side group with the air entraining function and the polyether branched chain with the foam stabilizing function, has strong air entraining capability, introduces fine and stable foam, obviously improves the fluidity of mixed concrete and the mechanical property and durability parameters of hardened concrete, and has environment-friendly production raw materials and preparation process and high cost performance.
Description
Technical Field
The invention belongs to the field of concrete admixtures, and particularly relates to a modified starch concrete air entraining agent and a preparation method thereof.
Background
The concrete air entraining agent is an additive capable of introducing a large amount of fine and uniform bubbles in the process of mixing concrete, and can obviously improve the workability of concrete mixtures and reduce the slump loss by introducing bubbles with proper size and proper amount, and improve the strength and the durability of frost resistance, permeability resistance, carbonization resistance and the like of hardened concrete. Modern concrete engineering puts higher requirements on construction performance such as water reduction rate, workability and fluidity, and application performance such as strength and durability. Under the condition that the basic components of the concrete are relatively stable, the performance of the used additives such as air entraining agents has important influence on the mixing performance and the hardening performance of the concrete. The mixing performance and microstructure of the concrete can be changed only by ten-thousandth of the cement amount of the air entraining agent in the concrete, so that the strength and durability of the concrete can be obviously improved.
The most commonly used air entraining agents for concrete are natural and synthetic air entraining agents. The natural air entraining agent mainly comprises rosin resin, triterpenoid saponin and the like, and the synthetic air entraining agent mainly comprises alkyl sodium sulfonate, alkyl sodium sulfate, sodium alkyl benzene sulfonate, fatty alcohol-polyoxyethylene ether and the like. The synthetic air entraining agent has the advantages of more types and good air entraining effect, and has the defects that the raw materials mainly depend on petrochemical products, the synthetic process has more steps and greater pollution, and petroleum resources face the crisis of exhaustion. At present, the preparation of concrete air entraining agents by means of the modification of biomass materials is still an important research direction, and the modified natural material air entraining agents have the advantages of renewable and environment-friendly main raw materials, green and environment-friendly preparation process, fine foam, stable foam and good compatibility with a cement system.
Starch is a natural high molecular material with huge yield, and is not only a main food on which people live but also an important chemical raw material. The chemical structure of starch is a long-chain macromolecule composed of glucose units, the structural units are also called glycosyl structures, and the structural units of starch are also important components of other natural high molecular materials. For example, the glycosyl structure is the main structural part of hydrolytic tanning in natural tannin extract, and the glycosyl structure is also the main structural part of triterpenoid saponin air entraining agent. Meanwhile, defoaming measures are adopted due to strong foamability of the product in the work of researching the modified starch for preparing other chemical materials. The starch structure unit glycosyl structure and the formed long-chain macromolecule containing a plurality of hydroxyl groups, ester bonds and glycosidic bonds are suitable for the polyether nonionic surfactant with hydroxyl groups and ether bonds, and the structure of the polyether nonionic surfactant is also lack of foam-increasing and foam-stabilizing structures such as anionic groups such as sulfonic groups and carboxyl groups.
Disclosure of Invention
The invention aims to provide a modified starch concrete air entraining agent and a preparation method thereof, wherein the prepared modified starch air entraining agent is based on the structure of natural high molecular material starch, the size of the molecular structure of the modified starch air entraining agent is regulated and controlled by degradation, and the molecular structure and the groups with foaming and foam stabilizing functions are introduced to the starch structure by graft polymerization, so that the prepared modified starch air entraining agent has fine and stable foam, can promote the formation of fine and uniform micropores in concrete, obviously improve the fluidity of the concrete, promote the formation of uniform, fine, closed and non-through microporous structures in the casting and forming process of the concrete, and obviously improve the mechanical property, durability parameters and performance of the concrete.
In order to achieve the purpose, the preparation method of the modified starch concrete air entraining agent provided by the invention comprises the steps of sequentially carrying out enzymatic degradation and oxidative degradation modification on natural high polymer material starch, and then sequentially carrying out enzymatic graft modification and peroxide initiated free radical graft polymerization modification on the natural high polymer material starch to obtain the modified starch concrete air entraining agent, which is suitable for concrete with the grade of C15-C60.
The method sequentially comprises the following steps of:
step one, degrading starch by enzyme:
adding 20-25 parts of starch and 0.3-0.5 part of high-temperature amylase into 100-150 parts of deionized water, stirring and heating to 70-80 ℃ for degradation reaction for 1.5-2.5 hours to obtain enzymatically degraded starch;
step two, oxidizing and degrading starch:
heating the enzyme-degraded starch solution to 90-95 ℃, adding 1.3-1.7 parts of ammonium persulfate, stirring and preserving heat for 3-4 hours to obtain oxidized degraded starch;
step three, enzyme catalysis modification for degrading starch:
adding 5-11 parts of 2, 4-dihydroxybenzenesulfonic acid, 6-12 parts of 3-aminobenzenesulfonic acid and 4-6 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degradation starch solution, stirring and heating to 35-40 ℃, adding 5-8 parts of buffer solution to adjust the pH of the system to 6.3-6.5, simultaneously dropwise adding 5-10 parts of horseradish peroxidase solution with the mass fraction of 0.08-0.16% and 13-18 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1-1.5 hours, and continuing to perform heat preservation reaction for 3.5-5 hours after the dropwise adding is finished to obtain modified starch;
step four, preparing the modified starch concrete air entraining agent:
adding 11-14 parts of methyl allyl polyoxyethylene ether into the graft modified starch solution, heating to 70-80 ℃, dropwise adding 1.5-2.5 parts of 30% hydrogen peroxide for 30-50 minutes, and keeping the temperature to continue reacting for 2.5-3.5 hours after dropwise adding to obtain the modified starch concrete air entraining agent.
The starch is one or a mixture of corn starch, potato starch and cassava starch.
The enzyme activity of the high-temperature amylase is 20000u/mg, the applicable temperature range is 60-90 ℃, and the applicable pH range is 6.0-7.0.
The buffer solution is prepared by dissolving 6.7-7.1 parts of sodium dihydrogen phosphate and 7.3-7.6 parts of disodium hydrogen phosphate in 100-120 parts of deionized water, and the pH value is 6.5-7.0.
The enzyme activity of the horseradish peroxidase is 330 u/mg, and 0.05-0.08 part of horseradish peroxidase is dissolved in 50-60 parts of deionized water to prepare a horseradish peroxidase solution with the mass fraction of 0.08-0.16%.
Compared with the prior art, the invention has the beneficial effects that:
1) the degraded starch with proper molecular weight and glycosyl structure is obtained by sequentially carrying out enzyme degradation and oxidative degradation modification on natural high molecular material starch, enzyme catalysis graft modification and peroxide-initiated free radical graft polymerization modification are carried out on the degraded starch, functional groups with dispersing, foaming, foam stabilizing and lubricating functions are introduced, and the purpose of preparing the air entraining agent with good air entraining effect is achieved.
2) The invention selects natural high molecular material starch as a base material, selects enzyme degradation and enzyme catalysis graft modification, has environment-friendly, green and high-efficiency preparation process, and has low cost, good use effect and high cost performance of the obtained air entraining agent.
3) The prepared modified starch air entraining agent has good performance and strong practicability, the critical micelle concentration of the prepared modified starch air entraining agent is 0.085-0.127 mmol/L, the minimum value of the surface tension is 31.26-33.53 mN/m, the foam height reaches and is maintained at 131-139 mm within 30min, the volume content of introduced gas is 3.6-4.7% when the doping amount in concrete is 0.012-0.018%, and the diameter of bubbles is mainly 60-180 mu m. The air entraining agent prepared by the invention has good compatibility with a polycarboxylic acid water reducing agent and a naphthalene water reducing agent, is suitable for concrete with the grade of C15-C60, and is applied to the concrete with the fluidity increased by 15-20%, the compressive strength increased by 13-25%, the flexural strength increased by 15-25%, and the durability parameter increased by one grade.
4) The modified tannin extract air entraining agent has good compatibility with a water reducing agent, can be independently used for air entraining of concrete, has good practicability, can be used in a naphthalene water reducing agent and polycarboxylic acid water reducing agent system, and has small mixing amount and good air entraining effect.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention include, but are not limited to, the scope shown in the following examples.
The invention provides a preparation method of a modified starch concrete air entraining agent, which comprises the following steps of:
step one, enzymatically degrading starch, namely adding 20-25 parts of starch and 0.3-0.5 part of high-temperature amylase into 100-150 parts of deionized water, stirring and heating to 70-80 ℃ for degradation reaction for 1.5-2.5 hours to obtain the enzymatically degraded starch.
And step two, oxidizing and degrading starch, namely heating the enzyme-degraded starch solution to 90-95 ℃, adding 1.3-1.7 parts of ammonium persulfate, stirring and preserving heat for 3-4 hours to obtain the oxidized and degraded starch.
And step three, carrying out enzyme catalytic modification on the degraded starch, namely adding 5-11 parts of 2, 4-dihydroxybenzenesulfonic acid, 6-12 parts of 3-aminobenzenesulfonic acid and 4-6 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degraded starch solution, stirring and heating to 35-40 ℃, adding 5-8 parts of buffer solution to adjust the pH value of the system to 6.3-6.5, simultaneously dropwise adding 5-10 parts of horseradish peroxidase solution with the mass fraction of 0.08-0.16% and 13-18 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1-1.5 hours, and continuing to carry out heat preservation reaction for 3.5-5 hours after the dropwise adding is finished to obtain the modified starch.
And step four, preparing the modified starch concrete air entraining agent, namely adding 11-14 parts of methyl allyl polyoxyethylene ether into the grafted modified starch solution, heating to 70-80 ℃, dropwise adding 1.5-2.5 parts of 30% hydrogen peroxide for 30-50 minutes, preserving heat after dropwise adding, and continuing to react for 2.5-3.5 hours to obtain the modified starch concrete air entraining agent.
The starch is one of corn starch, potato starch and cassava starch or a mixture of the corn starch, the potato starch and the cassava starch in any proportion.
The enzyme activity of the high-temperature amylase is 20000u/mg, the applicable temperature range is 60-90 ℃, and the applicable pH range is 6.0-7.0.
The buffer solution is prepared by dissolving 6.7-7.1 parts of sodium dihydrogen phosphate and 7.3-7.6 parts of disodium hydrogen phosphate in 100-120 parts of deionized water, and the pH value is 6.5-7.0.
The enzyme activity of the horseradish peroxidase is 330 u/mg, and 0.05-0.08 part of horseradish peroxidase is dissolved in 50-60 parts of deionized water to prepare a horseradish peroxidase solution with the mass fraction of 0.08-0.16%.
The methyl allyl polyoxyethylene ether is a milky white or light yellow flaky solid in appearance, the hydroxyl value is 21-26 mgKOH/g, the water content is less than 1%, the acid value is less than 0.5mgKOH/g, the unsaturated double-bond value is more than 0.37mmol/g, the relative molecular weight is 2160-2640, and the pH value is 5-7.
The 2, 4-dihydroxy benzene sulfonic acid, the 3-aminobenzene sulfonic acid, the 1, 2-dibutyl naphthalene-6-sodium sulfonate and the ammonium persulfate are all industrial grade, and the content is more than 98 percent.
The relative molecular mass of the enzyme-degraded starch is 600-1500.
The relative molecular mass of the oxidative degradation starch is 300-900.
The conversion rate of the graft modified starch reaches 96-98%, and the grafting rate reaches 78-87%.
The critical micelle concentration of the modified starch air entraining agent is 0.085-0.127 mmol/L, the minimum value of the surface tension is 31.26-33.53 mN/m, the foam height reaches and is maintained at 131-139 mm within 30min, the volume content of introduced gas is 3.6-4.7% when the mixing amount in concrete is 0.012-0.018%, and the diameter of bubbles is mainly 60-180 mu m. The air entraining agent prepared by the invention has good compatibility with a polycarboxylic acid water reducing agent and a naphthalene water reducing agent, is suitable for concrete with the grade of C15-C60, and is applied to the concrete with the fluidity increased by 15-20%, the compressive strength increased by 13-25%, the flexural strength increased by 15-25%, and the durability parameter increased by one grade.
Example 1:
step one, enzymatically degrading starch, namely adding 20 parts of starch and 0.3 part of high-temperature amylase into 100 parts of deionized water according to the mass parts (the same below), stirring and heating to 70 ℃ for degradation reaction for 1.5 hours to obtain the enzymatically degraded starch.
And step two, oxidizing and degrading starch, namely heating the enzyme-degraded starch solution to 90 ℃, adding 1.3 parts of ammonium persulfate, stirring and preserving heat for 3 hours to obtain the oxidized and degraded starch.
And step three, enzyme-catalyzed modification of the degraded starch, namely adding 5 parts of 2, 4-dihydroxybenzenesulfonic acid, 6 parts of 3-aminobenzenesulfonic acid and 4 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degraded starch solution, stirring and heating to 35 ℃, adding 5 parts of buffer solution to adjust the pH value of the system to 6.3, simultaneously dropwise adding 5 parts of horseradish peroxidase solution with the mass fraction of 0.08% and 13 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1 hour, and continuing to perform heat preservation reaction for 3.5 hours after the dropwise adding is finished to obtain the modified starch.
And step four, preparing the modified starch concrete air entraining agent, namely adding 11 parts of methyl allyl polyoxyethylene ether into the grafted modified starch solution, heating to 70 ℃, dropwise adding 1.5 parts of 30% hydrogen peroxide for 30 minutes, keeping the temperature after dropwise adding, and continuously reacting for 2.5 hours to obtain the modified starch concrete air entraining agent.
The critical micelle concentration of the modified starch air entraining agent is 0.085mmol/L, the minimum value of the surface tension is 31.26mN/m, the foam height reaches and is maintained at 131mm within 30min, the introduced gas volume content is 3.6% when the doping amount in C30 concrete is 0.012%, and the bubble diameter is mainly 60 mu m. The air entraining agent prepared by the invention has good compatibility with the polycarboxylic acid water reducing agent and the naphthalene water reducing agent, the fluidity of the applied concrete is increased by 15%, the compressive strength is increased by 13%, the flexural strength is increased by 15%, and the durability parameter is improved by one grade.
Example 2:
step one, enzymatically degrading starch, namely adding 25 parts of starch and 0.5 part of high-temperature amylase into 150 parts of deionized water according to the mass parts (the same below), stirring and heating to 80 ℃ for degradation reaction for 2.5 hours to obtain the enzymatically degraded starch.
And step two, oxidizing and degrading starch, namely heating the enzyme-degraded starch solution to 95 ℃, adding 1.7 parts of ammonium persulfate, stirring and preserving heat for 4 hours to obtain the oxidized and degraded starch.
And step three, enzyme-catalyzed modification of the degraded starch, namely adding 11 parts of 2, 4-dihydroxybenzenesulfonic acid, 12 parts of 3-aminobenzenesulfonic acid and 6 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degraded starch solution, stirring and heating to 40 ℃, adding 8 parts of buffer solution to adjust the pH value of the system to 6.5, simultaneously dropwise adding 10 parts of horseradish peroxidase solution with the mass fraction of 0.16% and 18 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1.5 hours, and continuing the heat preservation reaction for 5 hours after the dropwise adding is finished to obtain the modified starch.
And step four, preparing the modified starch concrete air entraining agent, namely adding 14 parts of methyl allyl polyoxyethylene ether into the grafted modified starch solution, heating to 80 ℃, dropwise adding 2.5 parts of hydrogen peroxide with the mass fraction of 30%, wherein the dropwise adding time is 50 minutes, and after dropwise adding, keeping the temperature and continuing to react for 3.5 hours to obtain the modified starch concrete air entraining agent.
The critical micelle concentration of the modified starch air entraining agent is 0.127mmol/L, the minimum value of the surface tension is 33.53mN/m, the foam height reaches and is maintained at 139mm within 30min, the volume content of introduced gas is 4.7 percent when the modified starch air entraining agent is mixed in C60 concrete at 0.018 percent, and the diameter of bubbles is mainly 180 mu m. The air entraining agent prepared by the invention has good compatibility with the polycarboxylic acid water reducing agent and the naphthalene water reducing agent, the fluidity of the applied concrete is increased by 20 percent, the compressive strength is increased by 25 percent, the flexural strength is increased by 25 percent, and the durability parameter is improved by one grade.
Example 3:
step one, enzymatically degrading starch, namely adding 22 parts of starch and 0.4 part of high-temperature amylase into 120 parts of deionized water according to the mass parts (the same below), stirring and heating to 73 ℃ for degradation reaction for 1.8 hours to obtain the enzymatically degraded starch.
And step two, oxidizing and degrading starch, namely heating the enzyme-degraded starch solution to 92 ℃, adding 1.5 parts of ammonium persulfate, stirring and preserving heat for 3.2 hours to obtain the oxidized and degraded starch.
And step three, enzyme-catalyzed modification of the degraded starch, namely adding 7 parts of 2, 4-dihydroxybenzenesulfonic acid, 8 parts of 3-aminobenzenesulfonic acid and 5 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degraded starch solution, stirring and heating to 37 ℃, adding 6 parts of buffer solution to adjust the pH value of the system to 6.4, simultaneously dropwise adding 7 parts of horseradish peroxidase solution with the mass fraction of 0.10% and 15 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1.2 hours, and continuing the heat preservation reaction for 3.8 hours after the dropwise adding is finished to obtain the modified starch.
And step four, preparing the modified starch concrete air entraining agent, namely adding 12 parts of methyl allyl polyoxyethylene ether into the grafted modified starch solution, heating to 72 ℃, dropwise adding 2.0 parts of 30% hydrogen peroxide for 4.0 minutes, keeping the temperature after dropwise adding, and continuing to react for 3.0 hours to obtain the modified starch concrete air entraining agent.
The critical micelle concentration of the modified starch air entraining agent is 0.095mmol/L, the minimum value of the surface tension is 31.87mN/m, the foam height reaches and is maintained at 136mm within 30min, the introduced gas volume content is 4.1 percent when the amount of the modified starch air entraining agent is 0.016 percent in C40 concrete, and the bubble diameter is mainly 80 mu m. The air entraining agent prepared by the invention has good compatibility with the polycarboxylic acid water reducing agent and the naphthalene water reducing agent, the fluidity of the applied concrete is increased by 17%, the compressive strength is increased by 18%, the flexural strength is increased by 17%, and the durability parameter is improved by one grade.
Example 4:
step one, enzymatically degrading starch, namely adding 23 parts of starch and 0.4 part of high-temperature amylase into 130 parts of deionized water according to the mass parts (the same below), stirring and heating to 75 ℃ for degradation reaction for 2.2 hours to obtain the enzymatically degraded starch.
And step two, oxidizing and degrading starch, namely heating the enzyme-degraded starch solution to 94 ℃, adding 1.6 parts of ammonium persulfate, stirring and preserving heat for 3.5 hours to obtain the oxidized and degraded starch.
And step three, enzyme-catalyzed modification of the degraded starch, namely adding 9 parts of 2, 4-dihydroxybenzenesulfonic acid, 8 parts of 3-aminobenzenesulfonic acid and 5 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degraded starch solution, stirring and heating to 38 ℃, adding 6 parts of buffer solution to adjust the pH value of the system to 6.45, simultaneously dropwise adding 8 parts of horseradish peroxidase solution with the mass fraction of 0.2% and 16 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1.3 hours, and continuing the heat preservation reaction for 4.2 hours after the dropwise adding is finished to obtain the modified starch.
And step four, preparing the modified starch concrete air entraining agent, namely adding 13 parts of methyl allyl polyoxyethylene ether into the grafted modified starch solution, heating to 75 ℃, dropwise adding 2.0 parts of 30% hydrogen peroxide for 40 minutes, preserving heat and continuously reacting for 3.0 hours after dropwise adding is finished, thus obtaining the modified starch concrete air entraining agent.
The critical micelle concentration of the modified starch air entraining agent is 0.105mmol/L, the minimum value of the surface tension is 32.51mN/m, the foam height reaches and is maintained at 135mm within 30min, the volume content of introduced gas is 4.2 percent when the amount of the modified starch air entraining agent is 0.015 percent in C50 concrete, and the diameter of bubbles is mainly 120 mu m. The air entraining agent prepared by the invention has good compatibility with the polycarboxylic acid water reducing agent and the naphthalene water reducing agent, the fluidity of the applied concrete is increased by 18 percent, the compressive strength is increased by 21 percent, the flexural strength is increased by 18 percent, and the durability parameter is improved by one grade.
Example 5:
step one, enzymatically degrading starch, namely adding 24 parts of starch and 0.4 part of high-temperature amylase into 140 parts of deionized water according to the mass parts (the same below), stirring and heating to 78 ℃ for degradation reaction for 2.2 hours to obtain the enzymatically degraded starch.
And step two, oxidizing and degrading starch, namely heating the enzyme-degraded starch solution to 94 ℃, adding 1.6 parts of ammonium persulfate, stirring and preserving heat for 3.8 hours to obtain the oxidized and degraded starch.
And step three, enzyme-catalyzed modification of the degraded starch, namely adding 9 parts of 2, 4-dihydroxybenzenesulfonic acid, 10 parts of 3-aminobenzenesulfonic acid and 5 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degraded starch solution, stirring and heating to 38 ℃, adding 7 parts of buffer solution to adjust the pH value of the system to 6.4, simultaneously dropwise adding 8 parts of horseradish peroxidase solution with the mass fraction of 0.14% and 17 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1.4 hours, and continuing the heat preservation reaction for 4.5 hours after the dropwise adding is finished to obtain the modified starch.
And step four, preparing the modified starch concrete air entraining agent, namely adding 13 parts of methyl allyl polyoxyethylene ether into the grafted modified starch solution, heating to 78 ℃, dropwise adding 2.3 parts of hydrogen peroxide with the mass fraction of 30%, wherein the dropwise adding time is 45 minutes, and after dropwise adding, keeping the temperature and continuing to react for 3.3 hours to obtain the modified starch concrete air entraining agent.
The critical micelle concentration of the modified starch air entraining agent is 0.115mmol/L, the minimum value of the surface tension is 333.05mN/m, the foam height reaches and is maintained at 138mm within 30min, the volume content of introduced gas is 4.3 percent when the content of the introduced gas in C45 concrete is 0.017 percent, and the diameter of bubbles is mainly 120 mu m. The air entraining agent prepared by the invention has good compatibility with the polycarboxylic acid water reducing agent and the naphthalene water reducing agent, the fluidity of the applied concrete is increased by 19%, the compressive strength is increased by 23%, the flexural strength is increased by 19%, and the durability parameter is improved by one grade.
In the above embodiments, embodiment 2 is the most preferred embodiment.
Claims (7)
1. A preparation method of the modified starch concrete air entraining agent is characterized by comprising the following steps:
firstly, the natural high molecular material starch is sequentially subjected to enzyme degradation and oxidative degradation modification, and then the natural high molecular material starch is sequentially subjected to enzyme catalysis graft modification and peroxide initiated free radical graft polymerization modification to prepare the modified starch concrete air entraining agent.
2. The method for preparing the modified starch concrete air entraining agent according to the claim 1 is characterized in that:
the method sequentially comprises the following steps of:
step one, degrading starch by enzyme:
adding 20-25 parts of starch and 0.3-0.5 part of high-temperature amylase into 100-150 parts of deionized water, stirring and heating to 70-80 ℃ for degradation reaction for 1.5-2.5 hours to obtain enzymatically degraded starch;
step two, oxidizing and degrading starch:
heating the enzyme-degraded starch solution to 90-95 ℃, adding 1.3-1.7 parts of ammonium persulfate, stirring and preserving heat for 3-4 hours to obtain oxidized degraded starch;
step three, enzyme catalysis modification for degrading starch:
adding 5-11 parts of 2, 4-dihydroxybenzenesulfonic acid, 6-12 parts of 3-aminobenzenesulfonic acid and 4-6 parts of 1, 2-dibutylnaphthalene-6-sodium sulfonate into the oxidative degradation starch solution, stirring and heating to 35-40 ℃, adding 5-8 parts of buffer solution to adjust the pH of the system to 6.3-6.5, simultaneously dropwise adding 5-10 parts of horseradish peroxidase solution with the mass fraction of 0.08-0.16% and 13-18 parts of hydrogen peroxide solution with the mass fraction of 30%, controlling the dropwise adding time to be 1-1.5 hours, and continuing to perform heat preservation reaction for 3.5-5 hours after the dropwise adding is finished to obtain modified starch;
step four, preparing the modified starch concrete air entraining agent:
adding 11-14 parts of methyl allyl polyoxyethylene ether into the graft modified starch solution, heating to 70-80 ℃, dropwise adding 1.5-2.5 parts of 30% hydrogen peroxide for 30-50 minutes, and keeping the temperature to continue reacting for 2.5-3.5 hours after dropwise adding to obtain the modified starch concrete air entraining agent.
3. The method for preparing the modified starch concrete air entraining agent according to the claim 1 or 2, characterized in that:
the starch is one or a mixture of corn starch, potato starch and cassava starch.
4. The method for preparing the modified starch concrete air entraining agent according to claim 3, characterized in that:
the enzyme activity of the high-temperature amylase is 20000u/mg, the applicable temperature range is 60-90 ℃, and the applicable pH range is 6.0-7.0.
5. The method for preparing the modified starch concrete air entraining agent according to claim 4, which is characterized in that:
the buffer solution is prepared by dissolving 6.7-7.1 parts of sodium dihydrogen phosphate and 7.3-7.6 parts of disodium hydrogen phosphate in 100-120 parts of deionized water, and the pH value is 6.5-7.0.
6. The method for preparing the modified starch concrete air entraining agent according to the claim 5 is characterized in that:
the enzyme activity of the horseradish peroxidase is 330 u/mg, and 0.05-0.08 part of horseradish peroxidase is dissolved in 50-60 parts of deionized water to prepare a horseradish peroxidase solution with the mass fraction of 0.08-0.16%.
7. A modified starch concrete air entraining agent obtained by the production method as claimed in claims 1 to 6.
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| CN101519453A (en) * | 2009-04-08 | 2009-09-02 | 孙彦峰 | Method for preparing water reducing agent of concrete |
| US20100139523A1 (en) * | 2005-09-09 | 2010-06-10 | Staker & Parson Companies | Concrete mixtures having stabilized foam admixture |
| CN107698686A (en) * | 2017-09-22 | 2018-02-16 | 安徽省阜南绿原化工有限公司 | A kind of preparation method of maleic anhydride esterification starch gas tracting subtractive agent |
| CN109279809A (en) * | 2018-09-30 | 2019-01-29 | 贵州凯襄新材料有限公司 | A kind of modified air entraining agent and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100139523A1 (en) * | 2005-09-09 | 2010-06-10 | Staker & Parson Companies | Concrete mixtures having stabilized foam admixture |
| CN101519453A (en) * | 2009-04-08 | 2009-09-02 | 孙彦峰 | Method for preparing water reducing agent of concrete |
| CN107698686A (en) * | 2017-09-22 | 2018-02-16 | 安徽省阜南绿原化工有限公司 | A kind of preparation method of maleic anhydride esterification starch gas tracting subtractive agent |
| CN109279809A (en) * | 2018-09-30 | 2019-01-29 | 贵州凯襄新材料有限公司 | A kind of modified air entraining agent and preparation method thereof |
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