阅读说明：本技术 一种混凝土减水剂及其制备方法 (Concrete water reducing agent and preparation method thereof ) 是由 尚志文 于 2020-12-26 设计创作，主要内容包括：本发明涉及一种混凝土减水剂,包括以下重量份组分,淀粉30-50份、丙烯酰胺100-150份、丙烯酸50-80份、异戊烯基聚氧乙烯醚(TPEG-2400)180-220份、30％过氧化氢30-40份、抗坏血酸3-6份、疏基乙醇0.1-0.2份。通过淀粉酶解、糊化,原料混合、酸碱度调节、浓缩等步骤制备成混凝土减水剂。本发明中的混凝土减水剂具有保水性、和易性、扩展性及抗压性好的特点。(The invention relates to a concrete water reducing agent which comprises, by weight, 30-50 parts of starch, 150 parts of 100-one acrylamide, 50-80 parts of acrylic acid, 220 parts of 180-one isopentenyl polyoxyethylene ether (TPEG-2400), 30-40 parts of 30% hydrogen peroxide, 3-6 parts of ascorbic acid and 0.1-0.2 part of mercaptoethanol. The concrete water reducer is prepared by the steps of starch enzymolysis, gelatinization, raw material mixing, pH value adjustment, concentration and the like. The concrete water reducing agent has the characteristics of good water retention, workability, expansibility and pressure resistance.)

1. The concrete water reducing agent is characterized by being prepared from the following raw materials in parts by weight:

30-50 parts of starch, 100-150 parts of acrylamide, 50-80 parts of acrylic acid, 220 parts of isopentenyl polyoxyethylene ether (TPEG-2400) 180-one, 30-40 parts of 30% hydrogen peroxide, 3-6 parts of ascorbic acid and 0.1-0.2 part of mercaptoethanol.

2. The concrete water reducing agent according to claim 1, which is prepared from the following raw materials in parts by weight:

35-42 parts of starch, 140 parts of acrylamide, 55-70 parts of acrylic acid, 205 parts of isopentenyl polyoxyethylene ether (TPEG-2400) 190-ion, 32-37 parts of 30% hydrogen peroxide, 3-5 parts of ascorbic acid and 0.12-0.16 part of mercaptoethanol.

3. The concrete water reducing agent according to claim 1, which is prepared from the following raw materials in parts by weight:

38 parts of starch, 130 parts of acrylamide, 67 parts of acrylic acid, 195 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 35 parts of 30% hydrogen peroxide, 4 parts of ascorbic acid and 0.15 part of mercaptoethanol.

4. The concrete water reducer of claim 1, wherein the starch is corn starch or potato starch.

5. The method for preparing the concrete water reducing agent of any one of claims 1 to 3, which is characterized by comprising the following steps:

s1, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s2, gelatinizing starch, keeping the gelatinized starch for 1-2 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky starch solution;

s3, mixing the raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, performing copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1-2h, continuously stirring in the dropwise adding process, and after dropwise adding is completed, performing heat preservation reaction for 1-1.5h at the temperature of 50-70 ℃;

s5, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S6, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

6. The preparation method of the concrete water reducer according to claim 5, wherein the alpha-amylase is alpha-1, 4-glucohydrolase, and the enzyme activity is 2000U/mL.

7. The preparation method of the concrete water reducer according to claim 5, wherein in the step S1, the enzymolysis reaction temperature is 65 ℃ and the reaction time is 40 min.

8. The preparation method of the concrete water reducer according to claim 5, wherein in the step S2, the starch gelatinization time is 1.5 h.

9. The preparation method of the concrete water reducer according to claim 5, wherein in the step S4, the heat preservation temperature is 60 ℃ and the heat preservation time is 1.2 h.

Technical Field

The invention relates to the field of concrete admixtures, in particular to a concrete water reducing agent and a preparation method thereof.

Background

The concrete water reducing agent is a concrete admixture which can reduce the water consumption for mixing under the condition of keeping the slump constant of concrete, and is one of the most widely applied concrete admixtures. The polycarboxylate superplasticizer plays an important role in the building industry, and has the advantages of high water reducing rate, good slump retaining performance, environmental protection and the like. However, with the gradual shortage of concrete gravel raw materials, concrete faces the dilemma of variable materials and unstable performance, bleeding phenomenon easily occurs by adding the existing polycarboxylic acid water reducing agent, a water permeable channel is easily formed in the concrete, the compactness of the concrete is affected, and the strength and the durability of the concrete are reduced. When the concrete mixture is composed of particles with different densities and sizes, the condition of insufficient cohesive force and easy delamination can occur due to different settlement of materials of all components, so that the defects of ' honeycombs ', pitted surfaces ' and the like are generated after the concrete is hardened, and the strength and the durability of the concrete are influenced.

Disclosure of Invention

The concrete water reducing agent produced by the method can form crystals and gel in concrete, improves the water retention performance of the concrete, ensures the water amount required by the hydration of the concrete, avoids the bleeding phenomenon of the concrete, can improve the cohesive force among components in the concrete, avoids the phenomena of layering, segregation and the like, and improves the strength and durability of the concrete.

The technical scheme for solving the technical problems is as follows:

a concrete water reducing agent comprises the following components in parts by weight:

30-50 parts of starch, 100-150 parts of acrylamide, 50-80 parts of acrylic acid, 220 parts of isopentenyl polyoxyethylene ether (TPEG-2400) 180-one, 30-40 parts of 30% hydrogen peroxide, 3-6 parts of ascorbic acid and 0.1-0.2 part of mercaptoethanol.

Preferably, the composition comprises the following components in parts by weight:

35-42 parts of starch, 140 parts of acrylamide, 55-70 parts of acrylic acid, 205 parts of isopentenyl polyoxyethylene ether (TPEG-2400) 190-ion, 32-37 parts of 30% hydrogen peroxide, 3-5 parts of ascorbic acid and 0.12-0.16 part of mercaptoethanol.

Preferably, the composition comprises the following components in parts by weight:

38 parts of starch, 130 parts of acrylamide, 67 parts of acrylic acid, 195 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 35 parts of 30% hydrogen peroxide, 4 parts of ascorbic acid and 0.15 part of mercaptoethanol.

Preferably, the starch is corn starch or potato starch.

A preparation method of a concrete water reducing agent comprises the following steps:

s1, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s2, gelatinizing starch, keeping the gelatinized starch for 1-2 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky starch solution;

s3, premixing raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, performing copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1-2h, continuously stirring in the dropwise adding process, and after dropwise adding is completed, performing heat preservation reaction for 1-1.5h at the temperature of 50-70 ℃;

s5, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S6, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

Preferably, the alpha-amylase is alpha-1, 4-glucohydrolase, and the enzyme activity is 2000U/mL.

Preferably, in the step S1, the enzymolysis reaction temperature is 65 ℃ and the reaction time is 40 min.

Preferably, in the step S2, the starch gelatinization time is 1.5 h.

Preferably, in the step S4, the holding temperature is 60 ℃ and the holding time is 1.2 h.

The invention has the beneficial effects that: after the starch is subjected to enzymolysis, amylose can be cut off, so that a high polymer is subjected to enzymolysis to form a plurality of short-chain starches, the molecular number is obviously increased while the cohesiveness of the starch is ensured, then the modified short-chain starches and acrylamide, acrylic acid and isopentenyl polyoxyethylene ether (TPEG-2400) are subjected to free radical copolymerization through a hydrogen peroxide-ascorbic acid redox system to form more copolymerization compounds, the free radicals of the short-chain starches have good cohesiveness, crystals and gel can be formed with water in concrete, the water is ensured to be reserved in the concrete, the copolymerization compounds have strong viscosity, the flowing property of the concrete is reduced, the layering and segregation phenomena of various components are avoided, and the water-retaining property, the strength and the durability of the water reducing agent are improved.

Detailed Description

The present invention will be better understood from the following examples. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.

Example 1

The embodiment provides a preparation method of a concrete water reducing agent, which comprises the following steps:

s1, preparing raw materials, namely preparing the required raw materials according to the following weight parts: 35 parts of corn starch, 105 parts of acrylamide, 55 parts of acrylic acid, 190 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 40 parts of 30% hydrogen peroxide, 6 parts of ascorbic acid and 0.2 part of mercaptoethanol.

S2, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s3, gelatinizing starch, keeping the gelatinized starch for 1 hour at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky white starch solution;

s3, mixing the raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, performing copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1h, continuously stirring in the dropwise adding process, and after dropwise adding is completed, performing heat preservation reaction for 1h at 50 ℃;

s5, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S6, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

The alpha-amylase is alpha-1, 4-glucohydrolase, and the enzyme activity is 2000U/mL.

Example 2

The embodiment provides a preparation method of a concrete water reducing agent, which comprises the following steps:

s1, preparing raw materials, namely preparing the required raw materials according to the following weight parts: 50 parts of potato starch, 145 parts of acrylamide, 75 parts of acrylic acid, 210 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 30 parts of 30% hydrogen peroxide, 3 parts of ascorbic acid and 0.1 part of mercaptoethanol.

S2, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s3, gelatinizing starch, keeping the gelatinized starch for 2 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky white starch solution;

s4, premixing raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, carrying out copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 2h, continuously stirring in the dropwise adding process, and after dropwise adding is finished, carrying out heat preservation reaction for 1.5h at 70 ℃;

s5, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S6, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

The alpha-amylase is alpha-1, 4-glucohydrolase, and the enzyme activity is 2000U/mL.

Example 3

The embodiment provides a preparation method of a concrete water reducing agent, which comprises the following steps:

s1, preparing raw materials, namely preparing the required raw materials according to the following weight parts: 42 parts of corn starch, 140 parts of acrylamide, 70 parts of acrylic acid, 195 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 37 parts of 30% hydrogen peroxide, 5 parts of ascorbic acid and 0.12 part of mercaptoethanol.

S2, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s3, gelatinizing starch, keeping the gelatinized starch for 2 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky white starch solution;

s4, premixing raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, performing copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1-2h, continuously stirring in the dropwise adding process, and after dropwise adding is completed, performing heat preservation reaction for 1.5h at the temperature of 60 ℃;

s5, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S6, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

The alpha-amylase is alpha-1, 4-glucohydrolase.

Example 4

The embodiment provides a preparation method of a concrete water reducing agent, which comprises the following steps:

s1, preparing raw materials, namely preparing the required raw materials according to the following weight parts: 38 parts of corn starch, 130 parts of acrylamide, 67 parts of acrylic acid, 195 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 35 parts of 30% hydrogen peroxide, 4 parts of ascorbic acid and 0.15 part of mercaptoethanol.

S2, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s3, gelatinizing starch, keeping the gelatinized starch for 1.5 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky starch solution;

s4, premixing raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, carrying out copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1.5h, continuously stirring in the dropwise adding process, and after the dropwise adding is finished, carrying out heat preservation reaction for 1.2h at the temperature of 60 ℃;

s5, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S6, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

The alpha-amylase is alpha-1, 4-glucohydrolase, and the enzyme activity is 2000U/mL.

Comparative example 1

The comparative example provides a preparation method of a concrete water reducing agent, which comprises the following steps:

s1, preparing raw materials, namely preparing the required raw materials according to the following weight parts: 38 parts of corn starch, 130 parts of acrylamide, 67 parts of acrylic acid, 195 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 35 parts of 30% hydrogen peroxide, 4 parts of ascorbic acid and 0.15 part of mercaptoethanol.

S2, gelatinizing starch, keeping the gelatinized starch for 1.5 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky starch solution;

s3, premixing raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s4, carrying out copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1.5h, continuously stirring in the dropwise adding process, and after the dropwise adding is finished, carrying out heat preservation reaction for 1.2h at the temperature of 60 ℃;

s4, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S5, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

Comparative example 2

The comparative example provides a preparation method of a concrete water reducing agent, which comprises the following steps:

s1, preparing raw materials, namely preparing the required raw materials according to the following weight parts: 25 parts of corn starch, 90 parts of acrylamide, 85 parts of acrylic acid, 230 parts of isopentenyl polyoxyethylene ether (TPEG-2400), 20 parts of 30% hydrogen peroxide, 6 parts of ascorbic acid and 0.2 part of mercaptoethanol.

S2, performing enzymolysis on starch, dissolving the starch in purified water, stirring and mixing uniformly to prepare a starch solution with the mass ratio of 10%, dissolving 5 mu L of medium-temperature alpha-amylase in 50mL of water, mixing uniformly, taking out 2 mu L of amylase solution, adding into 200mL of the starch solution, performing enzymolysis for 30-60min at the temperature of 60-70 ℃, and heating to 95 ℃ to inactivate the amylase;

s3, gelatinizing starch, keeping the gelatinized starch for 1.5 hours at the temperature of 95 ℃, and gelatinizing the starch to obtain a uniform milky starch solution;

s4, premixing raw materials, adding isopentenyl polyoxyethylene ether (TPEG-2400) and 30% hydrogen peroxide into a starch solution, adding a proper amount of water, uniformly stirring to obtain a solution A, uniformly mixing acrylamide and acrylic acid to obtain a raw material B, and uniformly mixing mercaptoethanol and ascorbic acid to obtain a raw material C;

s5, performing copolymerization reaction, namely slowly dropwise adding the raw material B and the raw material C into the solution A for 1.5h, continuously stirring in the dropwise adding process, and after the dropwise adding is finished, performing heat preservation reaction for 1.2h at the temperature of 50-70 ℃;

s6, adjusting pH, namely adding a 40% sodium hydroxide solution into the solution prepared in the step S4, and adjusting the pH of the solution to 6-7;

and S7, concentrating the solution, evaporating excessive water through concentration, and controlling the final solid content of the solution to be 20% to obtain the concrete water reducer.

The alpha-amylase is alpha-1, 4-glucohydrolase, and the enzyme activity is 2000U/mL.

And (3) performance testing:

the concrete water reducing agents prepared by the methods of examples 1 to 4 and comparative examples 1 to 2 were tested for their effects by concrete tests. The cement is conch brand P. C32.5R, the fly ash is class II fly ash, the sand is medium sand with fineness modulus of 2.7, and the coarse aggregate is 5-20 mm continuous graded broken stone. The concrete mixing proportion is as follows: cement 260kg/m³110kg/m of fly ash³770kg/m of sand³1080kg/m of crushed stone³160kg/m of water³. All the water reducing agent is mixed with cement in advance when in use based on the cement quality. The mixing amount of the concrete water reducing agent is 5 percent (mass ratio) of the cement amount, the concrete water reducing agent is added according to the cement amount, the indexes of fluidity, initial slump, expansion degree, workability, compressive strength and the like of cement paste are measured, the performance of the concrete is measured, and the measurement results are as follows:

TABLE 1 measurement results (mm) of concrete fluidity

Item	Example 1	Example 2	Example 3	Example 4	Comparative example 1	Comparative example 2
							Degree of fluidity	205.4	198.5	196.7	189.8	218.3	220.5

As can be seen from Table 1, the addition of the water-reducing agents of examples 1 to 4 can reduce the fluidity of concrete, and the reduction of fluidity is advantageous for improving the water retention of concrete, so that the water-reducing agents of examples 1 to 4 can improve the water retention.

TABLE 2 concrete Property measurement results

As can be seen from Table 2, by comparing the performances, the water reducing agents of examples 1 to 4 are added into concrete, so that the performances are improved, and the workability is better than that of the comparative example.

Through comprehensive analysis, the water reducing agents of the embodiments 1 to 4 can improve the water retention property and the workability, the comprehensive performance of the concrete is greatly improved compared with that of a comparative example, and the performance of the embodiment 4 is improved more obviously.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.