CN115536343B - Slump-retaining self-compaction high-strength concrete for high-temperature areas and preparation method thereof - Google Patents

Abstract

The application discloses slump-retaining self-compaction high-strength concrete for high-temperature areas and a preparation method thereof, wherein the concrete comprises the following components in mass: 320-380 parts of cement, 90-130 parts of mineral powder, 30-60 parts of micro silicon powder, 850-910 parts of machine-made sand, 800-1030 parts of crushed stone, 125-138 parts of water, 100-120 parts of filled auxiliary cementing material, 7-14 parts of HB-1 high-performance additive, wherein the HB-1 high-performance additive is a liquid composite polycarboxylate superplasticizer composed of a slump-retaining water-reducing component and a retarding component, and the slump-retaining water-reducing component comprises: the mass ratio of the retarder components is 94.9-98.1: 1.9-5.1, the structure and the performance of the admixture are optimized through adjusting the ingredients and the process of the admixture, so that the slump retaining capacity of the concrete is improved, the setting time is controllable, the cracking risk of the concrete is reduced, and the workability and the mechanical property of the concrete are improved.

Description

Slump-retaining self-compaction high-strength concrete for high-temperature areas and preparation method thereof

Technical Field

The application belongs to the field of building materials, and particularly relates to slump-retaining self-compaction high-strength concrete for high-temperature areas and a preparation method thereof.

Background

The Chinese operators are wide, different construction environments are often faced in the construction process due to different geographic positions, for example, construction is often faced in the hot climatic environment in the coastal areas of the south of China, and the actual temperature measurement at high temperature in summer can generally reach more than 35 ℃, which causes a plurality of inconveniences for high-strength concrete. Because the water gel of the high-strength concrete is smaller, water is easy to be dissipated in hot weather, so that the slump retaining performance of the concrete is insufficient, and the concrete is difficult to pour; secondly, the hydration reaction of the concrete at high temperature can be accelerated, and the high-strength concrete is easy to crack, so that the high-strength concrete with good slump retaining performance and good retarder effect needs to be designed.

Disclosure of Invention

The application provides slump-retaining self-compaction concrete for a high-temperature area and a preparation method thereof, and aims to solve the problems of poor slump-retaining performance, cracking of concrete caused by too high hydration speed and the like of high-strength concrete in a high-temperature environment.

The technical scheme provided by the application is as follows:

the slump retaining self-compaction high-strength concrete for the high-temperature area comprises the following components in mass: 320-380 parts of cement, 90-130 parts of mineral powder, 30-60 parts of micro silicon powder, 850-910 parts of machine-made sand, 800-1030 parts of crushed stone, 125-138 parts of water, 100-120 parts of filling type auxiliary cementing material and 7-14 parts of HB-1 high-performance additive.

The cement is P.O42.5 ordinary Portland cement. The mineral powder is S95-grade mineral powder, and the 28d activity is more than or equal to 97%. The activity of the silica fume 7d is more than or equal to 105, the water demand ratio is less than or equal to 118%, and the loss on ignition is less than or equal to 2.4%. The fineness modulus of the machine-made sand is 2.7-3.0, the MB value is less than or equal to 0.5, and less than or equal to 3.0 below 80 mu m. The continuous grading of the machine crushed stone is 4.75-26.5mm, the crushing value is less than or equal to 7.0%, and the needle-shaped content is less than or equal to 5%.

Furthermore, the filling type auxiliary material is stone powder with the maximum nominal particle diameter of below 80 mu m generated in the aggregate production process, and the MB value is less than or equal to 0.4.

Further, the HB-1 high-performance additive is a liquid composite polycarboxylate water reducer consisting of a slump-retaining water-reducing component and a retarder component, wherein the slump-retaining water-reducing component and the retarder component are mixed according to the mass ratio of 94.9-98.1: 1.9 to 5.1.

Further, the HB-1 high-performance additive comprises the following raw materials in parts by mass: 200-250 parts of acrylic acid, 25-30 parts of amine-terminated polyoxypropylene ether, 15-25 parts of isopentenol polyoxyethylene ether, 8-10 parts of concentrated sulfuric acid, 70-80 parts of toluene, 4-7 parts of ammonium persulfate, 5-8 parts of sodium bisulphite and 550-620 parts of deionized water.

Further, the preparation process of the slump retaining and water reducing component of the HB-1 high-performance additive comprises the following steps: weighing the components according to the mass ratio, putting amine-terminated polyoxypropylene ether, acrylic acid and 400-500 parts of deionized water into a three-neck flask, adding concentrated sulfuric acid as a catalyst, and toluene as a water-carrying agent, wherein the temperature is controlled at 100-120 ℃ and the reaction time is controlled at 8-10 hours to obtain an amidated unsaturated macromonomer; at the moment, the temperature is reduced to 30-50 ℃, isopentenol polyoxyethylene ether is added into a three-neck flask, ammonium persulfate is used as an oxidation initiator, and stirring and dissolving are carried out uniformly; dripping a mixed solution of a reducing initiator sodium bisulphite and 120-150 parts of deionized water into a flask at a constant speed for 1-2 h; and continuously stirring for 2 hours after the dripping is finished, and dripping NaOH solution after the reaction is finished to make the PH of the solution neutral, thus obtaining the slump retaining and water reducing component.

Further, the slump retaining and water reducing component has the following structure:

the water reducing effect of the structure mainly comprises the following two aspects: the main chain has carboxylic acid groups (-COOH) which lose one H during the stirring of the concrete ⁺ The double-electron layer is adsorbed on the surface of the cement particles, so that the double-electron layer is formed on the surface of the cement particles, and other cement particles are prevented from approaching; in addition, the structure has a large number of long branched chains, the long branched chains effectively exert the steric hindrance effect, and cement particles are efficiently dispersed to play a role in efficient water reduction. Meanwhile, as the structure is provided with a plurality of long-chain branches, a certain number of amide structures (-CON-) are arranged on the long-chain branches, the internal environment of the concrete gradually becomes alkaline along with the progress of hydration, carboxylic acid groups adsorbed on the surfaces of cement particles start to lose activity, amide groups in the branches react in the alkaline environment to generate new carboxylic acid groups, so that the main chain falls off, the branches are adsorbed on the surfaces of the cement particles, and at the moment, the space between cement particles cannot be further increased due to the fact that the branches are adsorbed on the surfaces of the cement particles, so that the slump retaining effect and the segregation preventing effect are achieved.

Further, the retarding component in the HB-1 high-performance additive is a mixture of N-acetamido glucose and sodium gluconate, and the mass ratio of the N-acetamido glucose to the sodium gluconate is (60-70): 30-40. N-acetamido glucose and sodium gluconate are glucose monomers with a plurality of anisotropic hydroxyl groups, when the cement hydration reaction just begins to proceed, the N-acetamido glucose and sodium gluconate can be adsorbed on the surface of cement particles to form a film so as to delay the progress of the cement hydration reaction, along with the hydrolysis of cement, the alkalinity of the internal environment of concrete is improved, the N-acetamido glucose is subjected to polycondensation reaction to generate chitosan, the chitosan is water-insoluble cellulose, along with the continuous progress of the N-acetamido glucose polycondensation reaction, the retarding effect of the concrete is weakened, and the sodium gluconate plays a role of buffering, so that the concrete is prevented from being quickly lost to cause the cracking due to the excessively fast setting speed of the concrete. Therefore, the purpose of adjusting the setting time of the concrete can be achieved by adjusting and controlling the N-acetylglucosamine and the sodium gluconate.

The preparation method of the concrete comprises the following steps:

step one: weighing cement, mineral powder, silica fume, machine-made sand, broken stone, water, filling auxiliary materials and additives according to the mass ratio of the components;

step two: adding the cement, mineral powder, micro silicon powder, machine-made sand, broken stone and filling auxiliary materials which are weighed according to the mass ratio of the components in the first step into a stirrer to stir for 30-60 s;

step three: and (3) adding the water and the additive which are weighed according to the mass ratio of the components in the first step into the mixture which is uniformly stirred in the second step, and continuously stirring for 120-180 s in a stirrer to obtain the slump retaining self-compaction high-strength concrete for high-temperature areas.

The beneficial effects of the application are as follows:

(1) The HB-1 high-performance additive prepared by the optimized formula and process has excellent 'supplementing effect', under the high-temperature condition, as moisture is continuously evaporated and the progress of hydration is accelerated, an amide structure in the additive continuously reacts to generate new carboxylic acid groups (-COOH) to be supplemented into slurry and re-adsorbed on the surfaces of cement particles, so that the slump retention time of concrete is prolonged, and the long-term maintenance of the workability of the concrete in the high-temperature environment is ensured;

(2) The N-acetylglucosamine and the sodium gluconate are mixed to form a retarding component, the N-acetylglucosamine can effectively reduce the surface tension of water, so that water molecules are easier to release from the agglomeration state of powder, the condensation time is controlled through polycondensation reaction, the sodium gluconate can effectively inhibit the early hydration of cement without influencing the final hydration of the cement, namely only the condensation time of the concrete is slowed down without influencing the final strength of the concrete, and the two components are mixed to cooperatively play a role.

The structure and the performance of the admixture are optimized through adjusting the ingredients and the process of the admixture, so that the slump retaining capacity of the concrete is improved, the setting time is controllable, the cracking risk of the concrete is reduced, the workability and the mechanical property of the concrete are improved, and the slump retaining self-compacting concrete for high-temperature areas is finally obtained.

Detailed Description

The technical solution of the present application is further illustrated by the following detailed description, which is given by way of illustration and not limitation.

The slump retaining and water reducing components in the HB-1 high-performance additive are weighed according to the parts by mass: 200-250 parts of acrylic acid, 25-30 parts of amine-terminated polyoxypropylene ether, 15-25 parts of isopentenol polyoxyethylene ether, 8-10 parts of concentrated sulfuric acid, 70-80 parts of toluene, 4-7 parts of ammonium persulfate, 5-8 parts of sodium bisulphite and 550-620 parts of deionized water. Placing amine-terminated polyoxypropylene ether, acrylic acid and 400-500 parts of deionized water into a three-neck flask, adding concentrated sulfuric acid as a catalyst, toluene as a water-carrying agent, controlling the temperature at 100-120 ℃ and the reaction time at 8-10 h to obtain an amidated unsaturated macromer; at the moment, the temperature is reduced to 30-50 ℃, isopentenol polyoxyethylene ether is added into a three-neck flask, ammonium persulfate is used as an oxidation initiator, and stirring and dissolving are carried out uniformly; dripping a mixed solution of a reducing initiator sodium bisulphite and 120-150 parts of deionized water into a flask at a constant speed for 1-2 h; and continuously stirring for 2 hours after the dripping is finished, and dripping NaOH solution after the reaction is finished to make the PH of the solution neutral, thus obtaining the slump retaining and water reducing component of the HB-1 high-performance additive.

In the mass ratio of the components of the embodiment, the cement is 360 parts, the water is 132 parts, the mineral powder is 100 parts, the silica fume is 50 parts, the machine-made sand is 905 parts, the filling auxiliary material is 100 parts, the broken stone is 960 parts, and the additive is 7-14 parts. Comparative example 1A conventional additive, which is CSP-9 retarder type additive of Guangdong red wall New Material Co., ltd, was used except that the additive was used in the same manner as in the examples. Wherein the retarding component is measured according to the weight percent of the cementing material. Adding the weighed cement, mineral powder, micro silicon powder, machine-made sand, broken stone and filling auxiliary materials into a stirrer, and stirring for 30-60 s to obtain a mixture; adding water and an additive into the uniformly stirred mixture, and continuously stirring for 120-180 s in a stirrer to obtain the slump retaining self-compacting high-strength concrete for high-temperature areas. The formulation of the additive of the examples is shown in the following table:

table 1 self-compacting concrete formulation with high slump loss resistance

The concrete obtained in comparative example 1 and examples 1 to 5 were tested for slump expansion, barrel pouring time, slump expansion with time, setting time, 7d strength and 28d strength, etc., wherein in order to simulate construction conditions in a high temperature region, a 2-hour slump expansion test was performed after placing the concrete in an incubator at 40 ℃ for 2 hours, and the results are shown in the following table:

table 2 concrete properties

As is apparent from the above table, in the cases of the comparative example 1 and the example 1, the concrete using HB-1 admixture in the example 1 has much better working performance than the conventional admixture under the condition that other components and processes are identical except the admixture, the fluidity of the concrete is further improved by utilizing the specific structure of the HB-1 admixture, the slump loss after being placed for 2 hours in the environment of 40 ℃ is only 10mm, the slump expansion is still kept at 600mm, and the self-compaction standard is still reached; and through comparative examples 1, 2 and 4, as the mixing amount of HB-1 additive increases, the expansion degree and the emptying time of the pouring barrel of the concrete are improved to a certain extent, and example 4 shows that the expansion degree and the pouring time of 2h of the concrete are not greatly changed and the segregation rate is 11% under the condition of being excessively mixed with 100% compared with comparative example 1, which indicates that the concrete has no bleeding and segregation phenomena caused by the excessive mixing of the additive, and further indicates that HB-1 and the concrete have good compatibility.

Examples 1, 3 and 5 show that the setting time of concrete is prolonged with the increase of the setting component by changing the amount of the setting component in the HB-1 admixture under the same admixture dosage, respectively, and the increment of the setting time and the ratio of the setting component show positive correlation, which indicates that the setting time of concrete can be accurately adjusted within a certain range by controlling the ratio of the setting component in the admixture. Meanwhile, because the HB-1 high-performance additive has the improving effect on workability, the probability of appearance quality problems in the concrete forming process is reduced, and the concrete forming process also has a certain improving effect on compressive strength.

The slump retaining and water reducing components of the HB-1 high performance additive in the above example comprise, by mass, 230 parts of acrylic acid, 26 parts of amine-terminated polyoxypropylene ether, 17 parts of isopentenyl alcohol polyoxyethylene ether, 8 parts of concentrated sulfuric acid, 75 parts of toluene, 6 parts of ammonium persulfate, 5 parts of sodium bisulphite and 560 parts of deionized water. Concrete was prepared by designing the slump retaining and water reducing components as shown in the following tables, examples 6 and 7, except for the slump retaining and water reducing components, the components were the same as in example 1.

TABLE 3 slump loss resistant composition comparative test

TABLE 4 slump loss control Water-reducing composition comparative test results

As can be seen from comparative examples 1, 6 and 7, the slump-retaining and water-reducing components of the HB-1 high-performance admixture prepared in the ranges taken by the respective raw materials can greatly improve the workability and slump-retaining performance of concrete as compared with comparative example 1. Therefore, the actual efficacy of the slump-retaining and water-reducing components can be ensured by adjusting the components in the range according to the price of each raw material and the actual processing condition.

In the above examples HB-1 retarder composition was N-acetylglucosamine: sodium gluconate is 67: the concrete was formulated with varying proportions of the retarder components as designed below, with the exception of the retarder components, examples 8 and 9, and comparative examples 2 and 3, which were identical to example 1.

Table 5 comparative test of retarder composition

Group of	Retarding component/mill	N-acetylglucosamine	Gluconic acid sodium salt
				Example 1	5	67	33
Example 8	5	70	30
				Example 9	5	60	40
Comparative example 2	5	100	0
				Comparative example 3	5	0	100

Table 6 concrete test results

As can be seen from comparative examples 1, 2 and 3, the retarder effect was reduced by using only N-acetylglucosamine as retarder component, and the initial setting time and final setting time interval were short, indicating that the cement hydration reaction was accelerated instead after the retarder effect of N-acetylglucosamine disappeared, and the strength of the concrete was reduced. The simple use of sodium gluconate as a retarder ensures the normal increase of the later strength of concrete, but greatly prolongs the setting time, which is unfavorable for the control of the setting time. As can be seen from comparative examples 1, 8 and 9, the controllability of setting time can be greatly increased by compounding the two, and at the same time, the strength of the concrete is not adversely affected, and the composition is prepared from N-acetylglucosamine: 60 to 70 percent of sodium gluconate: 30-40, and has better synergistic effect when the N-acetylglucosamine: sodium gluconate is 67:33, the best effect is achieved.

In conclusion, the slump retaining self-compaction high-strength concrete for the high-temperature area provided by the application improves the slump retaining capacity of the concrete, the maximum slump loss is only 10mm when the concrete is placed in an environment of 40 ℃, meanwhile, the setting time is controllable, the retarding components can be adjusted according to the requirements of different projects, the cracking risk of the concrete is reduced, and the workability and the mechanical property of the concrete are improved.

The foregoing is a further detailed description of the application in connection with the preferred embodiments, and it is not intended that the application be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the application, and these should be considered to be within the scope of the application.

Claims (2)

1. The slump retaining self-compaction high-strength concrete for the high-temperature area is characterized by comprising the following components in mass: 320-380 parts of cement, 90-130 parts of mineral powder, 30-60 parts of micro silicon powder, 850-910 parts of machine-made sand, 800-1030 parts of crushed stone, 125-138 parts of water, 100-120 parts of filled auxiliary cementing material and 7-14 parts of HB-1 high-performance additive; the filling type auxiliary cementing material is stone powder with the maximum nominal particle diameter of below 80 mu m generated in the aggregate production process, and the MB value is less than or equal to 0.4;

the HB-1 high-performance additive is a liquid composite polycarboxylate water reducer consisting of a slump-retaining water-reducing component and a retarding component, wherein the slump-retaining water-reducing component comprises: the mass ratio of the retarding components is as follows: 94.9-98.1: 1.9-5.1; the HB-1 high-performance additive comprises the following raw materials in parts by mass: 200-250 parts of acrylic acid, 25-30 parts of amine-terminated polyoxypropylene ether, 15-25 parts of isopentenyl alcohol polyoxyethylene ether, 8-10 parts of concentrated sulfuric acid, 70-80 parts of toluene, 4-7 parts of ammonium persulfate, 5-8 parts of sodium bisulfate and 550-620 parts of deionized water;

the preparation process of the slump-retaining water-reducing component of the HB-1 high-performance additive comprises the following steps: weighing the components according to the mass ratio, putting amine-terminated polyoxypropylene ether, acrylic acid and 400-500 parts of deionized water into a three-neck flask, adding concentrated sulfuric acid as a catalyst, and toluene as a water-carrying agent, wherein the temperature is controlled at 100-120 ℃ and the reaction time is controlled at 8-10 hours to obtain an amidated unsaturated macromer; at the moment, the temperature is reduced to 30-50 ℃, isopentenol polyoxyethylene ether is added into a three-neck flask, ammonium persulfate is used as an oxidation initiator, and stirring and dissolving are uniform; dropwise adding a mixed solution of a reductive initiator sodium bisulphite and 120-150 parts of deionized water into a flask at a constant speed for 1-2 hours; continuously stirring for 2 hours after the dripping is finished, and dripping NaOH solution after the reaction is finished to make the PH of the solution neutral, thus obtaining the slump retaining and water reducing component;

the retarding component in the HB-1 high-performance additive is a mixture of N-acetylglucosamine and sodium gluconate, and the mass ratio of the N-acetylglucosamine to the sodium gluconate is 67:33.

2. a method of preparing concrete according to claim 1, comprising the steps of:

step one: weighing cement, mineral powder, silica fume, machine-made sand, broken stone, water, filling type auxiliary materials and HB-1 high-performance additives according to the mass ratio of each component;

step two: adding the cement, mineral powder, micro silicon powder, machine-made sand, broken stone and filling auxiliary materials which are weighed according to the mass ratio of the components in the first step into a stirrer to stir for 30-60 s;

step three: and (3) adding the water weighed according to the mass ratio of the components in the first step and the HB-1 high-performance additive into the uniformly stirred mixture in the second step, and continuously stirring for 120-180 s in a stirrer to obtain the slump retaining self-compaction high-strength concrete for the high-temperature area.