CN112430015A - Large-mixing-amount fly ash concrete and preparation method thereof - Google Patents

Abstract

The application relates to the technical field of building materials, and particularly discloses a high-volume fly ash concrete and a preparation method thereof, wherein the concrete is prepared from the following raw materials in parts by weight: 980-1120 parts of coarse aggregate, 750-810 parts of fine aggregate, 180-240 parts of cement, 140-180 parts of water, 120-180 parts of fly ash, 0.2-0.8 part of activator and 4.8-6.0 parts of water reducer, wherein the activator comprises the following components in parts by mass: 1 triisopropanolamine-grafted cellulose with sodium sulfate; the concrete preparation method specifically comprises the following steps: s1, mixing main materials; s2, adding fly ash; and S3, adding a water agent. The excitant in the concrete formula can be used for improving the defect of low strength of the high-volume fly ash concrete.

Description

Large-mixing-amount fly ash concrete and preparation method thereof

Technical Field

The application relates to the technical field of building materials, in particular to a high-volume fly ash concrete and a preparation method thereof.

Background

The fly ash is one of industrial waste residues with large current discharge capacity in China, has complete particle shape, smooth surface and compact texture, and has a morphological effect, namely the fly ash contains more than 70 percent of glass microspheres with small particle size. The micro-beads and detritus with small particle size in the fly ash are equivalent to unhydrated cement particles in the set cement, and the ultra-fine micro-beads are equivalent to active nano materials, so that the structural strength of concrete and products thereof can be obviously improved and enhanced, and the homogeneity and compactness are improved.

Chinese patent of CN1749201A discloses a fly ash permeable pavement concrete, which is characterized by comprising cement, fly ash, broken stone, a water reducing agent and water, wherein the weight percentages of the components are as follows: 13.0-15.0% of ordinary portland cement, 2.0-4.0% of fly ash, 4.0-5.0% of water, 76.0-79.0% of coarse aggregate and 0.5-1.0% of high-efficiency water reducing agent.

With respect to the related art in the above, the inventors consider that: the blending amount of the fly ash in the concrete is small, in order to further enhance the structural strength, the homogeneity and the compactness of the concrete, the inventor improves the blending amount of the fly ash in the concrete, uses the fly ash with large blending amount to replace part of cement, namely, the blending amount ratio of the fly ash and the cement is increased, but the hydration reaction of the fly ash is slower than that of the cement, and the early hydration reaction speed of the concrete is reduced by increasing the blending amount of the fly ash, so that the early strength of the concrete is reduced. Therefore, how to ensure the early strength of the concrete while improving the mechanical property of the concrete by increasing the mixing amount of the fly ash is a difficult problem to be solved urgently.

Disclosure of Invention

In order to improve the defect of low strength of the large-volume fly ash concrete, the application provides the large-volume fly ash concrete and a preparation method thereof.

In a first aspect, the application provides a high-volume fly ash concrete, which adopts the following technical scheme:

the high-volume fly ash concrete is prepared from the following raw materials in parts by weight: 980-1120 parts of coarse aggregate, 750-810 parts of fine aggregate, 180-240 parts of cement, 140-180 parts of water, 120-180 parts of fly ash, 0.2-0.8 part of activator and 4.8-6.0 parts of water reducer, wherein the activator comprises the following components in parts by mass: 1 triisopropanolamine graft cellulose with sodium sulfate.

By adopting the technical scheme, the sodium sulfate reacts with the active ingredients in the cement and the fly ash to generate a gelled substance, so that the early hydration efficiency of the cement is improved, the fly ash is activated, the hydration time of the fly ash is shortened, and the early strength of the concrete is improved; the sodium sulfate has a better excitation effect under an alkaline condition, the triisopropanolamine grafted cellulose contains a large amount of hydroxyl groups, and can provide an alkaline condition for hydration reaction, so that the improvement effect of the sodium sulfate on the hydration reaction rate of cement and fly ash is promoted, and the triisopropanolamine grafted cellulose generates complex ions which are easy to dissolve in water with calcium ions, iron ions and the like in the cement, aluminum ions, silicon dioxide and the like in the fly ash, so that the solubility of cement particles and the surface of fly ash particles is improved, the dissolution of tricalcium aluminate and the like is promoted, the generation of a cementing material is accelerated, and the early strength of concrete is promoted to be increased.

Controlling the mass ratio of the triisopropanolamine grafted cellulose to the sodium sulfate to be (4-6): the addition amount of the sodium sulfate is small, because the sodium sulfate has an excellent excitation effect on the cement and the fly ash, but can react with hardened concrete to corrode the concrete, so that the durability and the construction performance of the concrete are influenced, the triisopropanolamine grafted cellulose has good corrosion resistance and water retention property, has the performance of making up the defect that the sodium sulfate corrodes the concrete, and the combination of the sodium sulfate and the triisopropanolamine grafted cellulose has the effects of improving the hydration rate of the cement and the fly ash and reducing the corrosion defect of the sodium sulfate.

Preferably, the high-volume fly ash concrete is prepared from the following raw materials in parts by weight: 1000-1100 parts of coarse aggregate, 760-790 parts of fine aggregate, 200-220 parts of cement, 150-170 parts of water, 135-165 parts of fly ash, 0.35-0.75 part of activator and 5.2-5.6 parts of water reducing agent, wherein the activator comprises the following components in parts by mass: 1 triisopropanolamine graft cellulose with sodium sulfate.

By adopting the technical scheme, the test data shows that when the raw materials are proportioned, the concrete has more excellent early strength performance and construction performance.

Preferably, the preparation method of the triisopropanolamine grafted cellulose comprises the following steps: 1) placing 100g of triisopropanolamine in a clean container A, adjusting the pH value to 5.5 by using 0.1mol/L glacial acetic acid, heating to 75 ℃, continuously and slowly dripping 70ml of epoxy chloropropane under the stirring state, and reacting for 2 hours to obtain an intermediate; 2) weighing 100ml of 40% cellulose solution, placing the cellulose solution in a clean container B, adjusting the pH value to 12 by using 30% sodium hydroxide solution, heating to 70 ℃, slowly dropwise adding the intermediate in the step 1), and reacting for 5 hours under a stirring state to obtain a triisopropanolamine grafted cellulose primary finished product; 3) and (3) purifying the primary finished product by ultrafiltration membranes with the molecular weights of 1000 and 10000 in sequence, washing the primary finished product by deionized water for 5 times, evaporating and concentrating, drying in vacuum, and grinding the primary finished product into powder to obtain the triisopropanolamine grafted cellulose.

By adopting the technical scheme, triisopropanolamine firstly generates an addition reaction with epichlorohydrin to generate an intermediate, and then generates a substitution reaction with cellulose in an alkaline environment, so that cellulose macromolecules are grafted to a molecular structure of triisopropanolamine.

Preferably, the triisopropanolamine-grafted cellulose is triisopropanolamine-grafted hydroxyethyl cellulose.

By adopting the technical scheme, the hydroxyethyl cellulose has larger molecular groups, and is grafted on a molecular ligand of triisopropanolamine to be beneficial to forming a steric hindrance effect, so that the dispersion stability of the cementing material in the concrete is improved, the agglomeration of the cementing material generated after the early hydration rate of the concrete is improved is avoided, and the reduction of the early strength of the concrete due to the agglomeration of the cementing material is avoided; the hydroxyethyl cellulose has a plurality of hydroxyl groups on the molecular structure, so that the hydroxyethyl cellulose has good water retention performance, and the occurrence of early segregation and bleeding of concrete is reduced.

Preferably, the triisopropanolamine-grafted cellulose is triisopropanolamine-grafted hydroxypropyl methylcellulose.

By adopting the technical scheme, the molecular group of the hydroxypropyl methyl cellulose has a plurality of hydroxyl groups, and the hydroxyl groups are favorable for providing an alkaline environment for the excitation of sodium sulfate and triisopropanolamine, so that the hydration reaction of cement and fly ash is promoted; the hydroxypropyl methyl cellulose also has good suspension stability, is beneficial to reducing the possibility of agglomeration of the generated cementing material, and improves the stability of the internal structure of the concrete, thereby ensuring the early strength stability and the construction performance of the concrete.

Preferably, the excitant also comprises N, N-dimethylethanolamine.

By adopting the technical scheme, the N, N-dimethylethanolamine has a good corrosion inhibition effect, has an effect of relieving corrosion of the sodium sulfate to concrete when being used together with the sodium sulfate, and has an effect of providing an alkaline environment for activating cement and fly ash by taking the N, N-dimethylethanolamine as an alcamine organic matter and containing hydroxyl on a molecular group, so that the excitation effect of the sodium sulfate and triisopropanolamine grafted cellulose is improved, and the early strength and the construction performance of the concrete are further improved.

Preferably, the coarse aggregate is continuous graded broken stone with the particle size of 15-25 mm and the crushing value of 5.5-8.1%.

By adopting the technical scheme, the test data shows that when the coarse aggregate adopts the continuous graded broken stone with the grain diameter of 15-25 mm and the crushing value of 5.5-8.1%, the early compressive strength of the concrete is higher, and the later-stage concrete is not easy to collapse.

Preferably, the fine aggregate is prepared from the following components in percentage by mass (3-4): 1, wherein the fineness modulus of the coarse sand is 4.5-5.5, and the fineness modulus of the fine sand is 0.5-1.5.

By adopting the technical scheme, when the fine aggregate is prepared by matching coarse sand with fineness modulus of 4.5-5.5 and fine sand with fineness modulus of 0.5-1.5, the fine sand can be filled into gaps of the coarse sand in the mixing process, so that the strength and stability of concrete are enhanced, and good gradation is formed between the fine aggregate and the coarse aggregate, which is beneficial to reducing the internal structure of the concrete and enabling the concrete structure to be more compact.

Preferably, the water reducing agent is a polycarboxylic acid water reducing agent.

By adopting the technical scheme, the polycarboxylic acid water reducing agent is adsorbed on the surfaces of concrete particles to enable the particles to show electrical property, and the particles repel each other due to the same charges, so that the concrete particles are dispersed to release excessive water among the particles to generate a water reducing effect; the polycarboxylic acid water reducing agent is low in price and easy to obtain, and the water reducing agent is selected as the water reducing agent of the application, so that the production cost is reduced.

In a second aspect, the application provides a preparation method of a large-volume fly ash concrete, which adopts the following technical scheme:

a preparation method of a large-volume fly ash concrete specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.

By adopting the technical scheme, 1/2 amount of water reducing agent is mixed in the fly ash, the fly ash has larger porosity, the water reducing agent can be filled in the pores of the fly ash, the rest of the water reducing agent is directly added into the system to firstly perform water reducing reaction, and then the water reducing agent filled in the fly ash performs water reducing reaction, so that the whole curing period of the concrete is ensured to have good water reducing performance, and the concrete is ensured to have good workability, fluidity and excellent strength performance.

In summary, the present application has the following beneficial effects:

1. because the excitant compounded by triisopropanolamine grafted cellulose and sodium sulfate is adopted, the triisopropanolamine grafted cellulose has the function of exciting the activation efficiency of the fly ash and the cement, also has the function of making up the defect that the concrete is not enough in durability due to the fact that the sodium sulfate erodes the concrete, and obtains the effect of obviously enhancing the early strength of the concrete.

2. According to the method for grafting cellulose by triisopropanolamine, which is preferably adopted in the application, because the substitution reaction is carried out under an alkaline condition, the prepared triisopropanolamine grafted cellulose has certain alkaline characteristics, so that a certain promotion effect is achieved on the excitation performance of sodium sulfate, and the activity excitation effect of the exciting agent on cement and fly ash is further improved.

3. According to the method, hydroxyethyl cellulose and triisopropanolamine are grafted, and the hydroxyethyl cellulose is grafted on a molecular ligand of triisopropanolamine, so that a steric hindrance effect is favorably ensured, the dispersion stability of the cementing material in the concrete is improved, the agglomeration of the cementing material generated after the early hydration rate of the concrete is improved is avoided, and the effect of stable early strength of the concrete is obtained.

4. In the application, hydroxypropyl methyl cellulose and triisopropanolamine are grafted, and the molecular group of the hydroxypropyl methyl cellulose has a plurality of hydroxyl groups, so that the hydroxyl groups are favorable for providing an alkaline environment for excitation of sodium sulfate and triisopropanolamine, and the effect of promoting the hydration reaction of cement and fly ash is obtained.

5. The N, N-dimethylethanolamine has a good corrosion inhibition effect, is matched with sodium sulfate for use, and has an effect of relieving the corrosion of the sodium sulfate to concrete.

Detailed Description

The present application is further described in detail with reference to the following examples.

The water reducing agent in the formulation of the application is purchased from Xinyuan German Rings building materials Co.

Examples of preparation of raw materials

Preparation example 1

The preparation method of the triisopropanolamine grafted hydroxyethyl cellulose comprises the following steps: 1) placing 100g of triisopropanolamine in a clean container A, adjusting the pH value to 5.5 by using 0.1mol/L glacial acetic acid, heating to 75 ℃, continuously and slowly dripping 70ml of epoxy chloropropane under the stirring state, and reacting for 2 hours to obtain an intermediate; 2) weighing 100ml of hydroxyethyl cellulose solution with the mass concentration of 40 percent, placing the hydroxyethyl cellulose solution into a clean container B, adjusting the pH value to 12 by using 30 percent sodium hydroxide solution, heating to 70 ℃, slowly dropwise adding the intermediate in the step 1), and reacting for 5 hours under a stirring state to obtain a triisopropanolamine grafted hydroxyethyl cellulose primary finished product; 3) and (3) purifying the primary finished product by ultrafiltration membranes with the molecular weights of 1000 and 10000 in sequence, washing the primary finished product by deionized water for 5 times, evaporating and concentrating, drying in vacuum, and grinding the product into powder to obtain the triisopropanolamine grafted hydroxyethyl cellulose.

Preparation example 2

The preparation method of the triisopropanolamine-grafted hydroxypropyl methyl cellulose comprises the following steps: 1) placing 100g of triisopropanolamine in a clean container A, adjusting the pH value to 5.5 by using 0.1mol/L glacial acetic acid, heating to 75 ℃, continuously and slowly dripping 70ml of epoxy chloropropane under the stirring state, and reacting for 2 hours to obtain an intermediate; 2) weighing 100ml of hydroxypropyl methyl cellulose solution with the mass concentration of 40 percent, placing the hydroxypropyl methyl cellulose solution into a clean container B, adjusting the pH value to 12 by using 30 percent sodium hydroxide solution, heating to 70 ℃, slowly dropwise adding the intermediate in the step 1), and reacting for 5 hours under a stirring state to obtain a triisopropanolamine grafted hydroxypropyl methyl cellulose primary finished product; 3) and (3) purifying the primary finished product by ultrafiltration membranes with the molecular weights of 1000 and 10000 in sequence, washing the primary finished product by deionized water for 5 times, evaporating and concentrating, drying in vacuum, and grinding the primary finished product into powder to obtain the triisopropanolamine grafted hydroxypropyl methyl cellulose.

Preparation example 3

The preparation method of the triisopropanolamine grafted hydroxymethyl cellulose comprises the following steps: 1) placing 100g of triisopropanolamine in a clean container A, adjusting the pH value to 5.5 by using 0.1mol/L glacial acetic acid, heating to 75 ℃, continuously and slowly dripping 70ml of epoxy chloropropane under the stirring state, and reacting for 2 hours to obtain an intermediate; 2) weighing 100ml of hydroxymethyl cellulose solution with the mass concentration of 40 percent, placing the hydroxymethyl cellulose solution into a clean container B, adjusting the pH value to 12 by using 30 percent sodium hydroxide solution, heating to 70 ℃, slowly dropwise adding the intermediate in the step 1), and reacting for 5 hours under a stirring state to obtain a triisopropanolamine grafted hydroxymethyl cellulose primary finished product; 3) and (3) purifying the primary finished product by ultrafiltration membranes with the molecular weights of 1000 and 10000 in sequence, washing the primary finished product by deionized water for 5 times, evaporating and concentrating, drying in vacuum, and grinding the primary finished product into powder to obtain the triisopropanolamine grafted hydroxymethyl cellulose.

Examples

Example 1

The high-dosage fly ash concrete comprises the following components in percentage by weight as shown in Table 1:

TABLE 1-examples 1-5 content of concrete component

Wherein the coarse aggregate is continuous graded broken stone with the grain diameter of 15mm and the crushing value of 5.5 percent;

the fine aggregate is prepared from the following components in percentage by mass: 1 and a mixture of coarse sand with fineness modulus of 4.5 and fine sand with fineness modulus of 0.5; the excitant is mixed with the following components in a mass ratio of 4: 1, triisopropanolamine-grafted hydroxyethyl cellulose and sodium sulfate, wherein the triisopropanolamine-grafted hydroxyethyl cellulose is prepared by preparation example 1;

the water reducing agent is a polycarboxylic acid water reducing agent;

the preparation method of the large-volume fly ash concrete specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.

Example 2

The components of the high-volume fly ash concrete are shown in the table 1;

wherein the coarse aggregate is continuous graded broken stone with the particle size of 17.5mm and the crushing value of 6.1 percent;

the fine aggregate is 3.25: 1 and a mixture of coarse sand with fineness modulus of 4.75 and fine sand with fineness modulus of 0.75; the exciting agent is mixed with the following components in a mass ratio of 4.5: 1, triisopropanolamine-grafted hydroxyethyl cellulose and sodium sulfate, wherein the triisopropanolamine-grafted hydroxyethyl cellulose is prepared by preparation example 1;

the water reducing agent is a polycarboxylic acid water reducing agent;

the preparation method of the large-volume fly ash concrete specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.

Example 3

The components of the high-volume fly ash concrete are shown in the table 1;

wherein the coarse aggregate is continuous graded broken stone with the particle size of 20mm and the crushing value of 6.8 percent;

the fine aggregate is prepared from the following components in percentage by mass of 3.5: 1 coarse sand with fineness modulus of 5 and fine sand with fineness modulus of 1;

the excitant is 5: 1, triisopropanolamine-grafted hydroxyethyl cellulose and sodium sulfate, wherein the triisopropanolamine-grafted hydroxyethyl cellulose is prepared by preparation example 1;

the water reducing agent is a polycarboxylic acid water reducing agent;

the preparation method of the large-volume fly ash concrete specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.

Example 4

The components of the high-volume fly ash concrete are shown in the table 1;

wherein the coarse aggregate is continuous graded broken stone with the particle size of 22.5mm and the crushing value of 7.4 percent;

the fine aggregate is prepared from the following components in percentage by mass of 3.75: 1 coarse sand with fineness modulus of 5.25 and fine sand with fineness modulus of 1.25; the exciting agent is prepared from the following components in a mass ratio of 5.5: 1, triisopropanolamine-grafted hydroxyethyl cellulose and sodium sulfate, wherein the triisopropanolamine-grafted hydroxyethyl cellulose is prepared by preparation example 1;

the water reducing agent is a polycarboxylic acid water reducing agent;

the preparation method of the large-volume fly ash concrete specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.

Example 5

The components of the high-volume fly ash concrete are shown in the table 1;

wherein the coarse aggregate is continuous graded broken stone with the particle size of 25mm and the crushing value of 8.1 percent;

the fine aggregate is prepared from the following components in percentage by mass: 1 coarse sand with fineness modulus of 5.5 and fine sand with fineness modulus of 1.5;

the excitant is prepared from the following components in percentage by mass: 1, triisopropanolamine-grafted hydroxyethyl cellulose and sodium sulfate, wherein the triisopropanolamine-grafted hydroxyethyl cellulose is prepared by preparation example 1;

the water reducing agent is a polycarboxylic acid water reducing agent;

the preparation method of the large-volume fly ash concrete specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.

Example 6, this example differs from example 3 in that:

the excitant is 5: 1, triisopropanolamine-grafted hydroxypropyl methylcellulose and sodium sulfate, wherein the triisopropanolamine-grafted hydroxypropyl methylcellulose is prepared by preparation example 2;

example 7, this example differs from example 3 in that:

the excitant is 5: 1 with sodium sulfate, wherein the triisopropanolamine-grafted hydroxymethylcellulose was prepared by preparation example 3;

example 8, this example differs from example 3 in that:

the exciting agent also comprises N, N-dimethylethanolamine, and the mass ratio of triisopropanolamine grafted hydroxyethyl cellulose, sodium sulfate and N, N-dimethylethanolamine is 5: 1: 2.

example 9, this example differs from example 3 in that:

the mass ratio of triisopropanolamine grafted hydroxyethyl cellulose to sodium sulfate in the exciting agent is 4: 1.

example 10, this example differs from example 3 in that:

the mass ratio of triisopropanolamine grafted hydroxyethyl cellulose to sodium sulfate in the exciting agent is 6: 1.

comparative example

Comparative example 1, this comparative example differs from example 3 in that:

no activator is added.

Comparative example 2, this comparative example differs from example 3 in that:

the activator is only triisopropanolamine grafted hydroxyethyl cellulose.

Comparative example 3, this comparative example differs from example 3 in that:

the activator is only triisopropanolamine grafted hydroxypropyl methyl cellulose.

Comparative example 4, which differs from example 3 in that:

the only activator is triisopropanolamine.

Comparative example 5, this comparative example differs from example 3 in that:

the activator is sodium sulfate only.

Comparative example 6, this example differs from example 3 in that:

the mass ratio of triisopropanolamine grafted hydroxyethyl cellulose to sodium sulfate in the exciting agent is 3: 1.

comparative example 7, this example differs from example 3 in that:

the mass ratio of triisopropanolamine grafted hydroxyethyl cellulose to sodium sulfate in the exciting agent is 7: 1.

comparative example 8, which differs from example 3 in that:

in the process of preparing the large-volume fly ash concrete, the water reducing agent is completely dispersed into the mixture of S1 and is uniformly stirred.

Performance test

1. And (3) detecting the compressive strength:

the compressive strength of the concrete mixed in the examples 1-18 and the comparative examples 1-6 is determined by referring to the standard GB/T50081-2002 of common concrete mechanical property test method. Immediately covering the surface of a cubic concrete compressive strength test piece with a waterproof film after the test piece is formed, and removing the mold within 24 hours after mold maintenance is carried out in an environment with the temperature of 20 +/-5 ℃ until final setting is achieved. Immediately placing the mold into a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than 95 percent for curing after removing the mold, and respectively measuring the compressive strength tests of 3d, 7d, 28d and 60 d. The results of the measurements are reported in table 2.

2. And (3) detecting the impermeability:

the permeability of the sample is detected according to GB/T50080-2002, a direct current electric quantity method is adopted for detection, the sample is put in vacuum to be saturated with water, the sample is electrified for 6 hours after being sealed, the current is recorded every 30 minutes, and the total electric quantity within 6 hours is recorded. The total electric quantity is more than 4000, the permeability is high, and the impermeability of concrete is poor; the total electric quantity is 2000-4000, the permeability is moderate, and the impermeability of the concrete is good; the total electric quantity is less than 2000, the permeability is low, and the impermeability of the concrete is excellent. The results of the measurements are reported in table 2.

TABLE 2 test data

By combining examples 1-5 and comparative example 1 and table 2, it can be seen that the early strength of the concrete is significantly improved by adding the activator to the concrete system compared with the early strength without adding the activator, which indicates that the activator has an obvious beneficial effect on improving the early strength of the concrete.

Combining example 3 and examples 6-7 with table 2, it can be seen that the complex excitation effect of the graft prepared by grafting triisopropanolamine with hydroxypropyl methylcellulose or hydroxyethyl cellulose is significantly better than the complex excitation effect of the graft prepared by grafting triisopropanolamine with hydroxymethyl cellulose and sodium sulfate, which indicates that the complex excitation effect of triisopropanolamine-grafted hydroxyethyl cellulose or triisopropanolamine-grafted hydroxypropyl methylcellulose and sodium sulfate is excellent.

By combining the example 3 and the example 8 and combining the table 2, it can be seen that the addition of N, N-dimethylethanolamine has a certain synergistic effect on the activation effect of the original activator, and the early strength, the later strength and the impermeability of the concrete are improved to a certain extent.

When the addition amount of sodium sulfate is too small, the early strength of the concrete is reduced, as can be seen by combining examples 3, 9 to 10 and comparative examples 6 to 7 with table 2, because the compounding effect of sodium sulfate and triisopropanolamine-grafted hydroxyethyl cellulose is not significant, and the activation effect of sodium sulfate is not sufficiently exerted; when the addition amount of the sodium sulfate is too much, the later strength of the concrete is reduced, because the concrete receives the corrosion effect of the sodium sulfate in the later period, and therefore, the control of the compounding ratio of the triisopropanolamine grafted hydroxyethyl cellulose and the sodium sulfate plays an important role in improving the early strength of the concrete and ensuring the later strength of the concrete.

By combining example 3 and comparative examples 2 to 3 and table 2, it can be seen that triisopropanolamine-grafted hydroxyethyl cellulose or triisopropanolamine-grafted hydroxypropyl methyl cellulose is not used in combination with sodium sulfate, and although a certain activation effect is achieved, the effect is not obvious in combination with sodium sulfate.

Combining example 3 and comparative example 4 with table 2, it can be seen that the early strength and impermeability of the concrete are reduced without performing hydroxyethyl cellulose grafting treatment on triisopropanolamine, which indicates that triisopropanolamine-grafted hydroxyethyl cellulose has an accelerating effect on improving the early strength and impermeability of the concrete.

By combining the example 3, the comparative example 1 and the comparative example 5 and combining the table 2, it can be seen that when the excitant is only sodium sulfate, the early strength of the concrete is improved, but the improvement effect is not significant, which indicates that the improvement effect of the combination of the triisopropanolamine grafted hydroxyethyl cellulose and the sodium sulfate on the early strength of the concrete is most obvious; and the use of sodium sulfate alone as an activator leads to a decrease in the later strength of concrete, because sodium sulfate has the disadvantage of corroding concrete, which reduces its durability.

It can be seen by combining example 3 and comparative example 8 and table 2 that the strength, impermeability and workability of the concrete are all reduced when the water reducing agent is added into the system, because part of the water reducing agent is mixed with the fly ash and then filled into the pores of the fly ash, and the time difference exists between the water reducing reaction of the water reducing agent and the water reducing agent directly added into the system, so that the good water reducing performance of the concrete in the whole curing period can be effectively ensured, and the strength, impermeability and workability of the concrete are all improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (10)

1. The high-volume fly ash concrete is characterized in that: the feed is prepared from the following raw materials in parts by weight: 980-1120 parts of coarse aggregate, 750-810 parts of fine aggregate, 180-240 parts of cement, 140-180 parts of water, 120-180 parts of fly ash, 0.2-0.8 part of activator and 4.8-6.0 parts of water reducer, wherein the activator comprises the following components in parts by mass: 1 triisopropanolamine graft cellulose with sodium sulfate.

2. The high-volume fly ash concrete as claimed in claim 1, wherein: the feed is prepared from the following raw materials in parts by weight: 1000-1100 parts of coarse aggregate, 760-790 parts of fine aggregate, 200-220 parts of cement, 150-170 parts of water, 135-165 parts of fly ash, 0.35-0.75 part of activator and 5.2-5.6 parts of water reducing agent, wherein the activator comprises the following components in parts by mass: 1 triisopropanolamine graft cellulose with sodium sulfate.

3. The high-volume fly ash concrete as claimed in claim 2, wherein: the preparation method of the triisopropanolamine grafted cellulose comprises the following steps: 1) placing 100g of triisopropanolamine in a clean container A, adjusting the pH value to 5.5 by using 0.1mol/L glacial acetic acid, heating to 75 ℃, continuously and slowly dripping 70ml of epoxy chloropropane under the stirring state, and reacting for 2 hours to obtain an intermediate; 2) weighing 100ml of 40% cellulose solution, placing the cellulose solution in a clean container B, adjusting the pH value to 12 by using 30% sodium hydroxide solution, heating to 70 ℃, slowly dropwise adding the intermediate in the step 1), and reacting for 5 hours under a stirring state to obtain a triisopropanolamine grafted cellulose primary finished product; 3) and (3) purifying the primary finished product by ultrafiltration membranes with the molecular weights of 1000 and 10000 in sequence, washing the primary finished product by deionized water for 5 times, evaporating and concentrating, drying in vacuum, and grinding the primary finished product into powder to obtain the triisopropanolamine grafted cellulose.

4. The heavily-doped fly ash concrete as claimed in claim 3, wherein: the triisopropanolamine-grafted cellulose is triisopropanolamine-grafted hydroxyethyl cellulose.

5. The heavily-doped fly ash concrete as claimed in claim 3, wherein: the triisopropanolamine-grafted cellulose is triisopropanolamine-grafted hydroxypropyl methyl cellulose.

6. The high-volume fly ash concrete as claimed in claim 1, wherein: the exciting agent also comprises N, N-dimethylethanolamine.

7. The high-volume fly ash concrete as claimed in claim 1, wherein: the coarse aggregate is continuous graded broken stone with the particle size of 15-25 mm and the crushing value of 5.5-8.1%.

8. The high-volume fly ash concrete as claimed in claim 1, wherein: the fine aggregate is prepared from the following components in percentage by mass (3-4): 1, wherein the fineness modulus of the coarse sand is 4.5-5.5, and the fineness modulus of the fine sand is 0.5-1.5.

9. The high-volume fly ash concrete as claimed in claim 1, wherein: the water reducing agent is a polycarboxylic acid water reducing agent.

10. The preparation method of the high-volume fly ash concrete as claimed in any one of claims 1 to 9, which is characterized by comprising the following steps: the preparation method specifically comprises the following preparation steps:

s1, main material mixing: weighing coarse aggregate, fine aggregate, cement, water, fly ash, an excitant and a water reducing agent according to the balance weight, and putting the coarse aggregate, the fine aggregate and the cement into a stirrer to be uniformly mixed to prepare a mixture;

s2, adding fly ash: 1/2 parts of water reducing agent is added into the fly ash, the mixture is added into the mixture of S1 and stirred uniformly after the water reducing agent is dispersed uniformly, and a dry powder mixture is prepared;

s3, adding a water agent: and adding the rest water reducing agent into the dry powder mixture, uniformly mixing, dispersing the activator into water, adding the aqueous solution into the mixture, and uniformly mixing to obtain a concrete finished product.