CN117326818B - A concrete hydration temperature rise inhibitor and its preparation method and application - Google Patents

Abstract

The invention discloses a concrete hydration temperature rise inhibitor, a preparation method and application thereof, belonging to the technical field of concrete additives, and comprising a temperature control component, a coagulation regulating component, an early strength component, a plasticizing component and a compacting component in parts by mass; the temperature control component consists of an organic component and an inorganic component in a mass ratio of (1.5-2) to 1; the organic components comprise modified starch-based materials, alcohol compounds and ester compounds; the inorganic component is one or more of steel slag, phosphorous slag and zeolite powder; the coagulation regulating component is one or more of citric acid, tartaric acid, sodium citrate, boric acid and zinc sulfate; the concrete hydration temperature rise inhibitor provided by the invention has the characteristics of adjusting the setting time, reducing the early hydration heat release rate, not affecting the total heat release amount and not negatively affecting the early strength of concrete, and can effectively control the temperature rise of mass concrete such as subway stations, tunnel lining side walls, rock-fill dam panel concrete and the like, reduce the cracking risk and prolong the service life of the concrete.

Description

A concrete hydration temperature rise inhibitor and its preparation method and application

Technical field

The invention belongs to the technical field of concrete admixtures, and in particular relates to a concrete hydration temperature rise inhibitor and its preparation method and application.

Background technique

The heat of cement hydration is the main cause of early temperature changes in concrete. The thermal conductivity of concrete is very low. The heat released by the early hydration of concrete is concentrated inside the concrete and is not easily lost. Especially for large-volume concrete, during the heating stage, the internal temperature rises sharply in 1 to 2 days, and the temperature rise can be as high as 50°C or more; during cooling During the stage, the internal temperature of the concrete drops to the ambient temperature, and at the same time, under the action of external constraints, a large shrinkage stress is generated. When the shrinkage stress is greater than the tensile strength of the concrete, cracks will occur in the concrete, seriously affecting its safety and service life.

In order to improve the quality and performance of concrete structures, reducing the temperature rise of concrete hydration is the fundamental measure to control the occurrence of temperature cracks. Temperature control measures commonly used in current projects include: 1) using medium-heat and low-heat cement with small hydration heat; 2) using large amounts of fly ash, slag and other admixtures to replace some cement with large hydration heat. Cement; 3) Control the temperature of the mold when pouring concrete, by cooling the mixing water; 4) Before concrete pouring, embed water pipes on site and pass in cooling water to cool the concrete (the water pipe cooling method is not suitable for thin-walled concrete structure). The above traditional methods have shortcomings such as unsatisfactory cooling effect, time and effort, not conducive to continuous construction on site, and low cost performance.

At present, adding hydration temperature rise inhibitors to concrete is one of the simplest and most effective methods. However, the preparation process of commercially available hydration temperature rise inhibitors is complex, and most of them contain a lot of retarding components, which affects the setting time of concrete. , mechanical properties, etc., all have varying degrees of negative effects. For concrete projects constructed at high temperatures, the effect of reducing the peak temperature rise is often not obvious, which limits its application in cast-in-place structural concrete.

Therefore, there is an urgent need in this field to develop a concrete hydration heat inhibitor with excellent performance. Through hydration temperature rise control technology, the risk of cracking of concrete caused by temperature drop shrinkage can be reduced to achieve the purpose of resisting cracking.

Contents of the invention

The purpose of the present invention is to provide a concrete hydration temperature rise inhibitor and its preparation method and application to solve the above-mentioned problems existing in the prior art.

One of the solutions provided by this invention:

A concrete hydration temperature rise inhibitor, including the following raw materials in parts by mass: 45 to 60 parts of temperature control components, 2 to 5 parts of setting adjustment components, 15 to 25 parts of early strength components, and plasticizing components 3 to 8 parts and 10 to 20 parts of dense components; the temperature control component is composed of organic components and inorganic components with a mass ratio of (1.5~2):1; the organic components include modified starch-based materials , alcohol compounds and ester compounds; the inorganic component is one or more of steel slag, phosphorus slag and zeolite powder; the coagulating component is citric acid, tartaric acid, sodium citrate, boric acid and zinc sulfate One or more of them; the early strength component is one or more of nano hydrated calcium silicate and nano calcium carbonate.

The concrete hydration temperature rise inhibitor provided by the invention contains a temperature control component that is a specific organic-inorganic composite material. The organic material contains a large number of hydroxyl groups and carboxyl groups, has a higher molecular weight, a larger number of functional groups and a larger Molecular coils are easy to complex Ca ²⁺ to reduce the free ion concentration, hinder the cement hydration process, and effectively reduce the hydration heat of concrete. Alcohol compounds and ester compounds in organic components can delay the initial hydration degree of cement and reduce the early hydration temperature rise. The hydration activity of steel slag, phosphorus slag and zeolite powder in inorganic materials is lower than that of Portland cement. Its porous structure can pre-absorb and encapsulate organic components and release them slowly in the alkaline environment of cement concrete without significantly extending the hydration induction period. , the organic and inorganic materials in the temperature control component work synergistically to achieve reasonable control of the hydration rate of concrete, which not only effectively controls the heat of hydration of concrete, but does not have a major impact on the setting time of concrete.

The setting-adjusting component is adsorbed on the surface of cement particles through small molecular compounds to form a wrapping layer, which reduces the cement hydration rate and thereby reduces the cement hydration heat during the acceleration period of the hydration reaction. Due to its low content, it has little effect on the setting time.

The early strength component reduces the cement hydration nucleation barrier through its nanocrystal nucleation effect and promotes the development of early strength of cement-based materials. During the cement hydration induction period, it can offset part of the effect of the temperature control component and the setting adjustment component on the setting time. It has an adverse effect on the maximum heat release rate during the cement hydration acceleration period and has a small impact on the total hydration heat. It can effectively improve the strength of concrete without significantly increasing the early hydration heat without affecting the later stage. The development of strength solves the problems of reduced early strength and prolonged setting time of concrete after the heat of hydration is reduced.

Preferably, the mass ratio of the modified starch, alcohol compounds and ester compounds is (4-6):(2-3):(1-2).

Preferably, the solubility of the modified starch-based material is 10% to 60%, and the modified starch-based material is one or more of white dextrin, yellow dextrin and cyclodextrin.

The alcohol compound is one or more of xylitol, mannitol, sorbitol and fructose; the ester compound is sorbitan monostearate, dextrin maleate and tricitrate. One or more ethyl esters.

The modified starch-based material is dextrin with a specific solubility. As the age of the concrete increases, hydration continues, the internal temperature of the concrete gradually increases, causing the solubility of dextrin to increase, and the effective dextrin concentration in the concrete pore liquid gradually increases. , the more obvious it is to reduce the hydration rate during the acceleration period, which is equivalent to the slow release of the dextrin component as the temperature increases. If the dextrin component is too soluble, it will have a higher dextrin concentration at an earlier age. At this time, the cement water If the dextrin component is in the induction period and the concrete has not yet set, the induction period will be extended, that is, the setting time will be significantly prolonged. If the solubility of the dextrin component is too small, the effective dextrin component content in the concrete will never be enough, and the effect of reducing the heat of hydration will be Not good.

More preferably, the plasticizing component is polycarboxylic acid high-performance water-reducing agent powder, with a water-reducing rate ≧28%; the dense component is ultrafine limestone powder, and the specific surface area of the ultrafine limestone powder is ≥550m ² /kg, 28d activity index ≥70%.

The plasticizing component can reduce the water consumption of concrete on the basis of ensuring the working performance of concrete, assist in reducing the early hydration heat, and compensate for the adverse effects of other components in the hydration temperature rise inhibitor on working performance.

The dense component optimizes the pore structure of concrete through the micro-aggregate filling effect, improves the compactness and toughness of concrete, thereby improving the crack resistance of concrete and further inhibiting the occurrence of temperature cracks.

The second solution provided by the present invention:

A method for preparing the above-mentioned concrete hydration temperature rise inhibitor, dry-mixing the weighed temperature control component, setting component, early strength component, plasticizing component and compacting component to obtain the above-mentioned concrete hydration temperature rise inhibitor. Concrete hydration temperature rise inhibitor.

The third solution provided by the present invention:

In the application of the above-mentioned concrete hydration temperature rise inhibitor in concrete preparation, the mixing amount of the concrete hydration temperature rise inhibitor is 0.3 to 1.0% of the amount of cementitious material.

Beneficial effects of the present invention:

The concrete hydration temperature rise inhibitor provided by the invention has the characteristics of regulating the setting time and reducing the early hydration heat release rate without affecting the total heat release and having no negative impact on the early strength of concrete. It can effectively control the lining of subway stations and tunnels. The temperature rise of large-volume concrete such as side walls and rockfill dam face concrete reduces the risk of cracking and extends its service life.

The present invention researches and designs the composition and proportion of key components of the concrete hydration temperature rise inhibitor. Through the synergistic effect of each component, it can effectively reduce the peak value of cement hydration heat release rate and reduce the early hydration heat without It affects the total amount of hydration heat release, improves the compactness and crack resistance of concrete, and at the same time does not cause obvious retardation and early strength reduction of concrete, effectively inhibits concrete temperature cracks, and all indicators meet JC/T 2608-2021 " "Concrete Hydration Temperature Rise Inhibitor" standard requirements.

The raw materials of the concrete hydration temperature rise inhibitor provided by the invention are all powders, and the raw materials come from a wide range of sources. The production can be realized through conventional dry mixing. The production process is simple and easy, low cost, suitable for industrial production, and has a simple preparation process. , efficient, green and economical, it will not have any adverse effects on the setting time, mechanical properties and durability of concrete. It is especially suitable for large-volume concrete, ultra-long structural concrete and thin-walled concrete that have temperature control and crack resistance requirements and high-temperature construction in summer. Structural concrete meets the construction temperature control requirements of various types of large-volume concrete and effectively reduces the risk of cracking.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range and any other stated value or value intermediate within a stated range is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents relate. In the event of conflict with any incorporated document, the contents of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to the skilled person from the description of the invention. The specification and examples are intended to be illustrative only.

The terms "includes", "includes", "has", "contains", etc. used in this article are all open terms, meaning including but not limited to.

"Parts" in the embodiments of the present invention are all "parts by mass" unless otherwise specified.

The raw materials in the examples of the present invention were all purchased.

Table 1

Example 1 A method for preparing a concrete hydration temperature rise inhibitor

Weigh 45 parts of the temperature control component, 5 parts of the setting component, 25 parts of the early strength component, 5 parts of the plasticizing component and 20 parts of the compacting component. The temperature control component is composed of organic components and inorganic components in a mass ratio of 1.5:1. The organic component is composed of white dextrin (solubility: 30%), xylitol and sorbitan monostearate in a mass ratio of 1.5:1. 4:2:1 composition, the inorganic component is steel slag; the setting component is citric acid, the early strength component is nanometer hydrated calcium silicate (median particle size is 100nm); the plasticizing component is polycarboxylic acid high Performance water-reducing agent powder; the dense component is ultra-fine limestone powder with a specific surface area of ^550m2 /kg and a 28d activity index of 70%; add the above components to the mixer, dry mix and stir evenly to obtain concrete hydration Temperature rise inhibitor.

Embodiment 2 A method for preparing a concrete hydration temperature rise inhibitor

Weigh 50 parts of the temperature control component, 4 parts of the setting component, 20 parts of the early strength component, 6 parts of the plasticizing component and 20 parts of the compacting component. The temperature control component consists of organic components and inorganic components according to The mass ratio is 1.5:1. The organic components are composed of yellow dextrin (solubility is 60%), mannitol and dextrin maleate in a mass ratio of 6:3:1. The inorganic components are phosphorus slag; the coagulation control group Divided into tartaric acid, the early-strength component is nanometer calcium carbonate powder (median particle size is 150nm); the plasticizing component is polycarboxylic high-performance water-reducing agent powder; the dense component has a specific surface area of 550m ² /kg , ultrafine limestone powder with a 28d activity index of 70%; add the above components to the mixer, dry mix and stir evenly to obtain the concrete hydration temperature rise inhibitor.

Embodiment 3 A method for preparing a concrete hydration temperature rise inhibitor

Weigh 55 parts of the temperature control component, 3 parts of the setting component, 18 parts of the early strength component, 7 parts of the plasticizing component and 17 parts of the compacting component. The temperature control component consists of organic components and inorganic components according to The mass ratio is 2:1. The organic component is composed of modified starch-based materials (mixed with white dextrin and cyclodextrin with equal mass, solubility is 60%), sorbitol and triethyl citrate in a mass ratio of 4:3 : 2 components, the inorganic component is zeolite powder; the coagulating component is sodium citrate, the early strength component is nanometer hydrated calcium silicate powder (median particle size is 100nm); the plasticizing component is polycarboxylic acid High-performance water-reducing agent powder; the dense component is ultra-fine limestone powder with a specific surface area of ^570m2 /kg and a 28d activity index of 75%; add the above components to the mixer, dry mix and stir evenly to obtain concrete water Temperature rise inhibitor.

Embodiment 4 A method for preparing a concrete hydration temperature rise inhibitor

Weigh 60 parts of the temperature control component, 2 parts of the setting component, 20 parts of the early strength component, 8 parts of the plasticizing component and 10 parts of the compacting component. The temperature control component consists of organic components and inorganic components according to The mass ratio is 2:1, the organic component is composed of white dextrin (solubility is 45%), fructose and triethyl citrate according to the mass ratio of 5:2:1, the inorganic component is zeolite powder; the coagulating component It is zinc sulfate, the early-strength component is nanometer calcium carbonate powder (median particle size is 150nm); the plasticizing component is polycarboxylic high-performance water-reducing agent powder; the dense component has a specific surface area of 580m ² /kg , ultrafine limestone powder with a 28d activity index of 78%; add the above components to the mixer, dry mix and stir evenly to obtain the concrete hydration temperature rise inhibitor.

Comparative example 1

Same as Example 1, the only difference is that no inorganic component is added to the temperature control component.

Comparative example 2

Same as Example 1, the only difference is that the added amount of the coagulation regulating component is 6 parts.

Comparative example 3

Same as Example 1, the only difference is that no early strength component is added.

Comparative example 4

The same as Example 1, the only difference is that the mass ratio of organic components and inorganic components is 1:1.

Comparative example 5

Same as Example 1, except that the organic component is composed of white dextrin (solubility is 90%), xylitol and sorbitan monostearate in a mass ratio of 4:2:1.

Test Methods

The recommended dosage of the concrete hydration temperature rise inhibitor provided by the present invention in mortar and concrete is 0.3% to 1.0% of the total amount of cementitious materials. The performance index requirements of JC/T 2068-2021 for inspected pastes and mortars mixed with concrete hydration temperature rise inhibitors are shown in Table 2.

Table 2 Performance requirements for inspected clean mortar mixed with concrete hydration temperature rise inhibitor

Test example 1

According to the test method of JC/T 2608-2021 "Concrete Hydration Temperature Rise Inhibitor", the hydration temperature rise inhibitors of Examples 1 to 4 and Comparative Examples 1 to 4 were respectively mixed into the mortar and concrete, and the mortar was tested. Heat of hydration reduction rate, setting time and compressive strength of concrete. The benchmark mix ratio of mortar is shown in Table 3. The cement is benchmark cement P.I42.5, the sand is standard sand, and the water is tap water. The benchmark mix ratio of concrete is shown in Table 4. The cement used in the test is benchmark cement P.I42.5, the fine aggregate is river sand with a fineness modulus of 2.5; the coarse aggregate is 5-20mm continuously graded gravel, and the water is Tap water, the actual amount of water used is the amount of water required when the initial slump of concrete is controlled at (80±10) mm. The test example without adding hydration temperature rise inhibitor was used as the blank group. The dosage of hydration temperature rise inhibitor in both mortar and concrete is 1.0% of the cementitious material dosage. The test results are shown in Table 5.

Table 3 Mortar basic mix ratio (kg/m ³ )

cement sand water 450 1350 180

Table 4 Basic mix ratio of concrete (kg/m ³ )

cement sand stone water 330 705 1140 215

Table 5 Hydration Temperature Rise Inhibitor Performance

It can be seen from the data in Table 5 that the performance of the concrete hydration temperature rise inhibitor provided by the present invention is excellent. In each embodiment, at a lower dosage, using benchmark cement testing, all performance indicators meet and far exceed JC/T2608. -2021 "Concrete Hydration Temperature Rise Inhibitor" standard requirements. The early stage hydration heat of each example is significantly lower than that of the blank group (base sample). At the same dosage of 1.0%, the 24h hydration heat reduction rate exceeds 40%, the 7d hydration heat reduction rate is less than 5%, and the setting time changes little. , the maximum final setting time difference is 1.5h, and the 3-day strength is slightly lower than the benchmark, but it reaches more than 90% of the benchmark. With the extension of age, the 7-28-day strength does not shrink, or even improves, 7-day and The 28-day compressive strength ratio is greater than 100%, and the project quality is fully guaranteed. It is especially suitable for large-volume concrete projects that need to reduce the risk of cracking and are constructed in summer. The temperature control component of Comparative Example 1 does not contain inorganic components, the 24h hydration heat reduction rate is less than 30%, and the 7d hydration heat reduction rate exceeds 15%, which does not meet the standard requirements. The coagulation-adjusting component of Comparative Example 2 is composed of 6 parts. The hydration heat reduction rate at 7 days exceeds 15%, the coagulation time is significantly prolonged, the 3-day strength is significantly reduced, and the 2-8 day compressive strength is also reduced. Comparative Example 3 does not contain early strength components. Although the hydration heat reduction effect is good and the setting time is slightly prolonged, the early strength, especially the 3-day compressive strength, is significantly lower than that of the blank group, which is not conducive to construction progress and safety. In Comparative Example 4, the proportion of inorganic components in the temperature control component is too large. It cannot pre-adsorb enough organic components and cannot continue to produce a sustained release effect, resulting in a poor effect of inhibiting hydration temperature rise, and excessive inorganic components. Too much will adversely affect early strength. In Comparative Example 5, the organic component in the temperature control component contains a dextrin component with too high solubility. The setting time is significantly prolonged and the early strength is significantly reduced. This is mainly because when the internal temperature of the concrete is lower at an earlier age, the solubility The higher dextrin has been basically completely dissolved. Even if the inorganic components in the temperature control component will adsorb a certain amount of organic components, the concrete will still have a higher dextrin concentration. At this time, the cement hydration is in the induction period and the concrete is still Without condensation, higher concentration of dextrin will be adsorbed on cement particles, prolonging the hydration induction period, that is, significantly prolonging the setting time, and at the same time delaying the hydration rate of cement minerals, resulting in a reduction in early strength. Therefore, the use of the concrete hydration temperature rise inhibitor provided by the present invention can effectively reduce the cement hydration heat, but has no significant impact on the early strength and setting time of concrete.

Test example 2

The American TA Company's TAM AIR isothermal calorimeter was used to measure the cement hydration heat release rate. The test temperature was 20°C. The test specimen was clean slurry, the water-cement ratio was 0.4, and the cement was the benchmark cement P.I42.5. The peak reduction rate of the heat release rate is used as a performance index to evaluate the hydration temperature rise inhibitor of the present invention. Under the same conditions, the greater the peak reduction rate of the heat release rate, the better the performance of the hydration temperature rise inhibitor in regulating the hydration temperature rise. Test The results are shown in Table 6.

Table 6 Isothermal calorimeter test data

It can be seen from Table 6 that when the dosage is 0.3% to 1.0%, the peak heat release rate reduction rate of the concrete hydration temperature rise inhibitor of the present invention exceeds 50%, and when the dosage is 1.0%, it is as high as more than 65%. , while the peak heat release rate reduction rate of a commercially available hydration temperature rise inhibitor (Wuhan Sanyuan Special Building Materials Co., Ltd., model: HHC-T) at a dosage of 1.0% is only 54.3%, proving that the concrete water content provided by the present invention The chemical temperature rise inhibitor has a good effect in regulating the hydration heat release rate at a lower dosage, and is particularly suitable for popularization and application.

The above-described embodiments only describe the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. All deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (7)

1. A concrete hydration temperature rise inhibitor, characterized in that it includes the following raw materials in parts by mass: 45 to 60 parts of temperature control components, 2 to 5 parts of setting adjustment components, and 15 to 25 parts of early strength components. parts, 3 to 8 parts of plasticizing component and 10 to 20 parts of compacting component; The temperature control component is composed of organic components and inorganic components with a mass ratio of (1.5~2):1; The organic components include modified starch-based materials, alcohol compounds and ester compounds; The inorganic component is one or more of steel slag, phosphorus slag and zeolite powder; The coagulation-adjusting component is one or more of citric acid, tartaric acid, sodium citrate, boric acid and zinc sulfate; The early strength component is one or more of nanohydrated calcium silicate and nanocalcium carbonate. 2. A concrete hydration temperature rise inhibitor according to claim 1, characterized in that the mass ratio of the modified starch-based material, alcohol compounds and ester compounds is (4-6): (2 ~3):(1~2). 3. A concrete hydration temperature rise inhibitor according to claim 1, characterized in that the solubility of the modified starch-based material is 10-60%. 4. A concrete hydration temperature rise inhibitor according to claim 1, characterized in that the plasticizing component is a polycarboxylic acid high-performance water-reducing agent, and the dense component is ultra-fine limestone powder. 5. A concrete hydration temperature rise inhibitor according to claim 4, characterized in that the ultrafine limestone powder has a specific surface area ≥ 550 m 2 /kg and a 28d activity index ≥ 70%. 6. A method for preparing a concrete hydration temperature rise inhibitor according to any one of claims 1 to 5, characterized in that the weighed temperature control component, set adjustment component, early strength component, plastic The hydration component and the compacting component are dry-mixed and stirred evenly to obtain the concrete hydration temperature rise inhibitor. 7. Application of the concrete hydration temperature rise inhibitor according to any one of claims 1 to 5 in concrete preparation, characterized in that the blending amount of the concrete hydration temperature rise inhibitor is cementitious material 0.3~1.0% of the dosage.