阅读说明：本技术 增强型混凝土内养护高吸水微球材料及制备方法 (Enhanced concrete internal curing high water absorption microsphere material and preparation method thereof ) 是由 何锐 谈亚文 房建宏 陈华鑫 薛成 薛兆峰 段德峰 于 2019-09-23 设计创作，主要内容包括：本发明提供了一种增强型混凝土内养护高吸水微球材料及制备方法,包括以下原料制成：纳米二氧化硅、壳聚糖、戊二醛、阿拉伯胶、甲基丙烯酸、冰乙酸、异丙苯过氧化氢、氯化亚铁和乙醇钠。本发明通过改善水泥浆体与骨料的过渡区,修饰水泥基材料内部的微观结构,降低孔隙率,提高力学性能。其整个制备工艺流程也相对较为简单,不需要专业的技术人员操作指导,只需要按照本发明的叙述操作进行即可。本发明制备增强型混凝土内养护高吸水微球不论是对水泥混凝土的强度、耐久性以及使用寿命等方面都有明显的改善。(The invention provides an enhanced concrete internal curing high water absorption microsphere material and a preparation method thereof, wherein the enhanced concrete internal curing high water absorption microsphere material is prepared from the following raw materials: nano silicon dioxide, chitosan, glutaraldehyde, Arabic gum, methacrylic acid, glacial acetic acid, cumene hydroperoxide, ferrous chloride and sodium ethoxide. The invention modifies the microstructure in the cement-based material by improving the transition area of the cement paste and the aggregate, reduces the porosity and improves the mechanical property. The whole preparation process flow is relatively simple, does not need the operation guidance of professional technicians, and only needs to be operated according to the description of the invention. The reinforced concrete internal curing super absorbent microspheres prepared by the invention obviously improve the strength, durability, service life and other aspects of cement concrete.)

1. The reinforced concrete internal curing high-water-absorption microsphere material is characterized by being prepared from the following raw materials: nano silicon dioxide, chitosan, glutaraldehyde, Arabic gum, methacrylic acid, glacial acetic acid, cumene hydroperoxide, ferrous chloride and sodium ethoxide.

2. The reinforced concrete internal curing super absorbent microsphere material of claim 1, which is prepared from the following raw materials in parts by weight: 8 to 10 percent of nano silicon dioxide, 15 to 20 percent of chitosan, 25 to 30 percent of glutaraldehyde, 4 to 5 percent of Arabic gum, 25 to 30 percent of methacrylic acid, 3.3 to 5 percent of glacial acetic acid, 0.4 to 0.5 percent of cumene hydroperoxide, 0.1 to 0.2 percent of ferrous chloride and 5 to 8 percent of sodium ethoxide, wherein the sum of the weight parts of the raw materials is 100 percent.

3. The reinforced concrete inside-curing superabsorbent microsphere material of claim 1, wherein the nanosilica has an average particle size of 20 nm.

4. A method for preparing an enhanced concrete internal curing high water absorption microsphere material, which is characterized by adopting the formula of the enhanced concrete internal curing high water absorption microsphere material as claimed in any one of claims 1 to 3; the method specifically comprises the following steps:

step one, weighing the raw materials according to the weight of a formula;

dispersing the nano silicon dioxide in water, preparing nano silicon dioxide suspension with the mass concentration of 3%, and stirring;

step three, diluting the glacial acetic acid with water to obtain a glacial acetic acid dilute solution with the mass concentration of 1%;

step four, mixing chitosan and Arabic gum, adding the glacial acetic acid diluted solution with the mass concentration of 1% prepared in the step three, and stirring to form a diluted acid solution A of the chitosan and the Arabic gum;

adding methacrylic acid into water to prepare a dilute solution with the mass concentration of 15%, adding sodium ethoxide, cooling to room temperature, adding cumene hydroperoxide and ferrous chloride in the process of continuous stirring, and fully dissolving to prepare a mixture B;

step six, adding cyclopentane and Span 80 into a container, and stirring at constant temperature to form an oil phase C;

step seven, adding the nano-silica suspension prepared in the step two into the oil phase C, stirring at a constant temperature under the protection of inert gas, adding the dilute acid solution A and glutaraldehyde prepared in the step four in the continuous stirring process, and stirring at an increased speed to prepare a mixed solution D;

step eight, adding the mixture B prepared in the step five into the mixed liquid D prepared in the step seven for reaction to prepare a compound E;

and step nine, taking out the compound E prepared in the step eight, washing with a solvent, and volatilizing the solvent to prepare the enhanced concrete internal curing high water absorption microsphere material.

5. The method for preparing the reinforced concrete internally cured high water absorption microsphere material as claimed in claim 4, wherein in the second step, the stirring is performed by magnetic stirring for 20 mm; in the fourth step, magnetic stirring is adopted for stirring, and the stirring time is 30 mm.

6. The method for preparing the reinforced concrete internally cured high water absorption microsphere material as claimed in claim 4, wherein in the sixth step, the constant temperature is a constant temperature water bath environment with a constant temperature of 30 ℃; the stirring is carried out for 20min at 200 r/min.

7. The method for preparing the reinforced concrete internal curing high water absorption microsphere material as claimed in claim 4, wherein in the sixth step, in the oil phase C, Span 80 accounts for 5-8% of the mass fraction of cyclopentane.

8. The method for preparing the reinforced concrete internally cured high water absorption microsphere material as claimed in claim 4, wherein in the seventh step, the inert gas protection is nitrogen gas introduction; the constant temperature is a constant temperature water bath environment of 40 ℃; the stirring is carried out for 10min at the speed of 200 r/min; the stirring at the speed of rising is carried out for 30min at the speed of 400 r/min.

9. The method for preparing the reinforced concrete internally cured high water absorption microsphere material as claimed in claim 4, wherein in the step eight, the temperature in the whole reaction process is controlled to be 40-45 ℃, and the reaction time is 6 h.

10. The method for preparing the reinforced concrete internally cured high water absorption microsphere material of claim 4, wherein in the ninth step, the solvent is absolute ethyl alcohol, and the washing is performed for 3-5 times.

Technical Field

The invention relates to the field of building materials, relates to a concrete internal curing material, and particularly relates to an enhanced concrete internal curing high-water-absorption microsphere material and a preparation method thereof.

Background

The concrete is widely applied to projects such as sea-crossing bridges, high-speed railways, high-rise buildings and the like by virtue of the advantages of excellent mechanical property, higher durability and the like and obvious economic, social and environmental benefits. However, with the rapid development of economy in China, new architectural styles put higher demands on concrete. The current buildings are required to be higher, larger and have long service life, which requires that the concrete has better durability and larger bearing capacity. Compared with common concrete, the high-performance concrete has many performance indexes higher than that of the common concrete, but the common high-performance concrete has the characteristics of low water-cement ratio, high-activity mineral admixture addition and the like, so that the early hydration is fast, and the internal relative humidity is fast to reduce. Meanwhile, due to the self-compact structure, external curing water is difficult to enter the interior of the concrete, and moisture required by later cement hydration cannot be supplemented, so that the phenomena of chemical shrinkage, self-drying and self-shrinkage of the cement-based composite material are serious, the early cracking sensitivity of concrete is greatly improved, and a huge obstacle is caused in engineering application.

Based on the structural characteristics of the modern concrete, the current general research considers that water is provided inside the concrete for later hydration, namely, the internal curing technology is the most feasible and effective method for solving the problem of early shrinkage and cracking of the high-strength concrete. International union of materials and structural research experiments RILEM in 2003 defines internal curing as "introducing water capable of acting as curing into concrete", and divides the curing materials into two categories — Lightweight Aggregate (LAW) and super absorbent resin (SAP). The SAP is used as a novel internal curing material, plays a role of a reservoir in the concrete by virtue of unique water absorption performance and water retention performance, can gradually release water to maintain the internal relative humidity of the cement-based composite material at a higher level along with the changes of the internal and external humidity difference, pressure difference, pH value and the like of SAP particles in the hydration process of cement, the hydration of the subsequent gelled material cannot be stopped due to water shortage, the cracking phenomenon of the early self-drying and shrinkage of the cement-based material can be effectively relieved and controlled, and the negative influence on other performances of the concrete is far lower than that of the former. Thus, SAPs have become the inner care materials that have been continuously studied and applied in recent years. However, because of the limited current technologies, the effect of the SAP incorporation on the concrete strength is highly controversial, and in addition, the incorporation of the SAP deteriorates the workability of the concrete and does not effectively control the water release rate during the hydration of the cement concrete.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an enhanced concrete internal curing super absorbent microsphere material and a preparation method thereof, and solve the technical problem that the strength of concrete is reduced due to the fact that the existing absorbent material guarantees the water absorption performance.

In order to solve the technical problems, the invention adopts the following technical scheme:

the reinforced concrete internal curing high-water-absorption microsphere material is characterized by being prepared from the following raw materials: nano silicon dioxide, chitosan, glutaraldehyde, Arabic gum, methacrylic acid, glacial acetic acid, cumene hydroperoxide, ferrous chloride and sodium ethoxide.

Specifically, the feed is prepared from the following raw materials in parts by weight: 8 to 10 percent of nano silicon dioxide, 15 to 20 percent of chitosan, 25 to 30 percent of glutaraldehyde, 4 to 5 percent of Arabic gum, 25 to 30 percent of methacrylic acid, 3.3 to 5 percent of glacial acetic acid, 0.4 to 0.5 percent of cumene hydroperoxide, 0.1 to 0.2 percent of ferrous chloride and 5 to 8 percent of sodium ethoxide, wherein the sum of the weight parts of the raw materials is 100 percent.

The invention also has the following technical characteristics:

the average particle size of the nano silicon dioxide is 20 nm.

The invention also discloses a preparation method of the reinforced concrete internal curing high water absorption microsphere material, which adopts the formula of the reinforced concrete internal curing high water absorption microsphere material.

The method specifically comprises the following steps:

step one, weighing the raw materials according to the weight of a formula;

dispersing the nano silicon dioxide in water, preparing nano silicon dioxide suspension with the mass concentration of 3%, and stirring;

step three, diluting the glacial acetic acid with water to obtain a glacial acetic acid dilute solution with the mass concentration of 1%;

step four, mixing chitosan and Arabic gum, adding the glacial acetic acid diluted solution with the mass concentration of 1% prepared in the step three, and stirring to form a diluted acid solution A of the chitosan and the Arabic gum;

adding methacrylic acid into water to prepare a dilute solution with the mass concentration of 15%, adding sodium ethoxide, cooling to room temperature, adding cumene hydroperoxide and ferrous chloride in the process of continuous stirring, and fully dissolving to prepare a mixture B;

step six, adding cyclopentane and Span 80 into a container, and stirring at constant temperature to form an oil phase C;

step seven, adding the nano-silica suspension prepared in the step two into the oil phase C, stirring at a constant temperature under the protection of inert gas, adding the dilute acid solution A and glutaraldehyde prepared in the step four in the continuous stirring process, and stirring at an increased speed to prepare a mixed solution D;

step eight, adding the mixture B prepared in the step five into the mixed liquid D prepared in the step seven for reaction to prepare a compound E;

and step nine, taking out the compound E prepared in the step eight, washing with a solvent, and volatilizing the solvent to prepare the enhanced concrete internal curing high water absorption microsphere material.

In the second step, magnetic stirring is adopted for stirring, and the stirring time is 20 mim.

In the fourth step, magnetic stirring is adopted for stirring, and the stirring time is 30 mm.

In the sixth step, the constant temperature is a constant temperature water bath environment with the constant temperature of 30 ℃; the stirring is carried out for 20min at 200 r/min.

In the sixth step, in the oil phase C, the Span 80 accounts for 5-8% of the mass fraction of cyclopentane.

In the seventh step, the inert gas is protected by introducing nitrogen; the constant temperature is a constant temperature water bath environment of 40 ℃; the stirring is carried out for 10min at the speed of 200 r/min; the stirring at the speed of rising is carried out for 30min at the speed of 400 r/min.

In the eighth step, the temperature in the whole reaction process is controlled to be 40-45 ℃, and the reaction time is 6 hours.

In the ninth step, the solvent is absolute ethyl alcohol, and washing is carried out for 3-5 times.

Compared with the prior art, the invention has the following technical effects:

the nano silicon dioxide component in the reinforced concrete internal curing super absorbent microsphere provided by the invention is in a quasi-particle structure with a spherical, flocculent and reticular microstructure, so that a skeleton of the concrete internal curing super absorbent microsphere can be provided, the nano silicon dioxide has volcanic ash activity and is subjected to chemical reaction with Calcium Hydroxide (CH) to generate additional hydrated calcium silicate (C-S-H), and the C-S-H is a main component for enhancing the strength and density of cement-based hardened slurry. Silica particles reduce Ca (OH) in the slurry due to their pozzolanic activity₂The content and the grain size of the compound (B), and the crystal nucleus effect promote C₃S and C₂S generates C-S-H gel, and the filling effect enables the C-S-H gel to be used as nano filler to be filled in gaps among the C-S-H gel. Therefore, the pozzolanic activity, the crystal nucleus effect and the filling effect of the nano silicon dioxide can promote the early hydration of cement, improve the transition region of cement paste and aggregate, modify the microstructure in the cement-based material, reduce the porosity and improve the mechanical property.

The chitosan molecule in the reinforced concrete internal curing super absorbent microsphere provided by the invention is a natural polymer, and the structure has active amino groups and high chemical activity. The structure contains a large number of hydrophilic groups, the swelling can be realized to a certain degree in the solution with high water content, a network framework can be provided for the graft polymerization reaction of organic monomers in the synthesis process of the concrete internal curing high water absorption microsphere, the polymerization degree of the polymerization reaction is improved, and the liquid absorption rate of the internal curing high water absorption microsphere is increased. Glutaraldehyde can react with glutaraldehyde for cross-linking, which occurs mainly between molecules and also within molecules. The crosslinked product has stable properties and is generally not easy to dissolve. In addition, the chitosan has good emulsibility, film forming property and balling property, and can effectively improve the synthetic effect of the concrete internal curing high water absorption microspheres.

(III) organic monomer methacrylic acid in the reinforced concrete internal curing high water absorption microsphere provided by the invention is continuously grafted and polymerized, and nano silicon dioxide is continuously filled and wrapped, so that the liquid absorption rate of the internal curing material can be obviously improved. In addition, the excellent liquid absorption and liquid storage effects can more effectively adjust the humidity distribution in the concrete to a certain extent, ensure the water demand of the concrete in the hydration process and promote the secondary hydration of cement and mineral admixtures. The hydration degree of the cement-based material can be effectively improved for the second time, and the internal pores of the concrete are optimized. Therefore, the reinforced concrete internal curing super absorbent microspheres prepared by the method greatly contribute to the strength, durability, service life and the like of cement concrete.

(IV) the whole preparation process flow of the invention is relatively simple, does not need the operation guidance of professional technicians, and only needs to be carried out according to the description of the invention.

Drawings

FIG. 1 is an SEM image of the reinforced concrete internal curing super absorbent microsphere material of the invention.

The present invention will be explained in further detail with reference to examples.

Detailed Description

In this application, it should be noted that:

span 80, i.e., sorbitan monooleate.

The average particle diameter of the nano silicon dioxide is 20nm, the silicon dioxide content is more than or equal to 99 percent, and the specific surface area is 150-200 m²(iv) per gram, pH 4-7.

The chitosan is food grade, and the deacetylation degree is 80-90%.

The following embodiments of the present invention are provided, and it should be noted that the present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention are within the protection scope of the present invention.