CN111793165B - A kind of seawater eroded fair-faced concrete admixture and preparation method thereof - Google Patents

Abstract

The invention discloses a seawater erosion resistant clear water concrete admixture, which comprises the following components in percentage by weight: 3-6 parts of unsaturated carboxylic acid, 3-6 parts of unsaturated carboxylic acid derivative, 0.3-0.7 part of unsaturated sulfonate, 1-4 parts of silane coupling agent, 0.2-0.6 part of initiator, 0.15-0.5 part of vitamin C and 85-95 parts of water. The invention directly prepares the seawater corrosion resistant concrete admixture by adopting a free radical polymerization method, improves the stability of the concrete admixture, provides the strength between hardened concrete aggregate slurry, reduces microcracks and further improves the durability of concrete. The additive does not contain nitrite, complex acid salt and the like, is chlorine-free, does not have heat source reaction at normal temperature, has mild reaction conditions, simple process, environmental protection and high efficiency, can greatly improve the durability of concrete serving in marine environment, and is suitable for popularization and application.

Description

A kind of seawater eroded fair-faced concrete admixture and preparation method thereof

technical field

The invention belongs to the technical field of building materials, and in particular relates to a seawater eroded fair-faced concrete admixture and a preparation method thereof.

Background technique

In recent years, with the continuous development of my country's economy, a large number of major basic projects are under construction or planning in my country's marine areas. However, the areas where these basic projects are located are difficult to transport, the gradation of concrete coarse and fine aggregates is poor, and the prepared high-fluidity clear water Concrete is prone to problems such as poor slurry stability: on the one hand, when the concrete is hardening, the water in the cement slurry will migrate to the hydrophilic aggregate, forming a water film layer on the surface of the aggregate, which will remain in the hardened concrete. On the other hand, the ocean climate is very windy, and the deformation caused by changes in environmental humidity and temperature is different, and there is stress at the interface between the aggregate and the cement paste, which is prone to micro-cracks. Based on the above problems, the interface of the obtained concrete is full of original micro-cracks before being subjected to the load; however, under the load, shear stress and tensile stress are further generated at the interface between the slurry and the aggregate, which leads to the expansion of the original micro-cracks. With the increase of stress, the cracks continue to grow and extend to the cement stone, which eventually leads to the fracture of the slurry, which causes the premature failure of the engineering structure, and the service life does not reach the designed service life, thereby causing huge economic losses.

In view of the above technical problems, in order to improve the durability of fair-faced concrete materials in marine engineering, the preparation of fair-faced concrete structures should first ensure that the concrete has good slurry stability and the compactness of hardened concrete, so as to resist the erosion and penetration of external harmful substances. Focus on the structural strength of the interface between the aggregate and the slurry inside the concrete.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a seawater eroded fair-faced concrete admixture for the deficiencies in the prior art, which can effectively improve the stability of the concrete mixture, improve the pore structure, and enhance the structural strength of the interface between the concrete aggregate and the slurry, In addition, the preparation method involved is environmentally friendly and has mild reaction conditions, and is suitable for popularization and application.

To achieve the above object, the technical scheme adopted in the present invention is:

An admixture for seawater eroded fair-faced concrete, each component and its parts by weight include: 3-6 parts of unsaturated carboxylic acid, 3-6 parts of unsaturated carboxylic acid derivatives, 0.3-0.7 parts of unsaturated sulfonic acid, 1-4 parts of silane coupling agent, 0.2-0.6 part of initiator, 0.15-0.5 part of vitamin C, and 85-95 parts of water.

In the above scheme, the unsaturated carboxylic acid is one or both of acrylic acid and methacrylic acid.

In the above scheme, the unsaturated carboxylic acid derivative is acrylamide.

In the above scheme, the unsaturated sulfonate is sodium methacrylate.

In the above scheme, the silane coupling agent is aminopropyltrimethoxysilane, diethylenetriaminomethyloxysilane, vinyltrimethyloxysilane, vinyl(2-methylethoxy)silane , one or more of γ-aminopropyltrimethoxysilane.

In the above scheme, the initiator is one or more of hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate.

The above-mentioned preparation method of seawater-resistant clear-water concrete admixture comprises the following steps:

1) Weigh each raw material by proportion, each raw material and its share by weight include: 3-6 parts of unsaturated carboxylic acid, 3-6 parts of unsaturated carboxylic acid derivatives, 0.3-0.7 part of unsaturated sulfonic acid, silane 1-4 parts of coupling agent, 0.2-0.6 part of initiator, 0.15-0.5 part of vitamin C, 85-95 parts of water;

2) Add the weighed unsaturated carboxylic acid derivative, silane coupling agent and water into the reaction kettle; then under stirring conditions, control the temperature at 10-40 ° C; add initiator, and under stirring conditions, dropwise Add the aqueous solution of unsaturated carboxylic acid, unsaturated sulfonate and vitamin C, and control the dripping within 2.5-3.5 hours; after dripping, stir and react at room temperature for 1-1.5 hours to obtain the anti-seawater erosion concrete admixture .

The principle of the present invention is:

In the high molecular polymer prepared in the present invention, the amide group is combined with water to form a hydrogen bond, which increases the viscosity of the solution, reduces the migration rate of water to the aggregate, and the silicon-oxygen bond in the molecular structure can interact with calcium ions in the cement particles. The formation of strong chemical bonds increases the bridging effect between cement particles, increases the movement resistance of aggregates and water molecules, and can be evenly wrapped by cement particles around the aggregates, and at the same time, the hydrophobic groups such as alkoxy groups in the molecular structure are reduced. The surface tension of the solution is reduced, and the water molecules required for the wetting of the cement particles and the aggregates are reduced, so that the water molecules between the aggregates and the cement particles are reduced, and the strength between the hardened concrete aggregate and the slurry increases, and microcracks occur. reduce.

Compared with the prior art, the beneficial effects of the present invention are:

1) the present invention directly prepares a kind of anti-seawater erosion fair-faced concrete admixture product by the method of free radical polymerization, without chlorine, without nitrite, chromate etc., on the basis of effectively guaranteeing or further improving concrete strength, It can greatly improve the durability of concrete in the marine environment;

2) The reaction conditions involved in the present invention are mild, and the reaction at room temperature without a heat source is adopted, the process is simple, environmentally friendly and efficient, and is suitable for popularization and application.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1

A kind of anti-seawater erosion fair-faced concrete admixture, the preparation method of which comprises the following steps:

5 parts by weight of acrylamide, 2 parts by weight of aminopropyltrimethoxysilane and 70 parts by weight of deionized water were added to the reaction kettle; then under stirring conditions and a temperature of 35 ° C, 0.3 parts by weight of ammonium persulfate was once Join in the reactor, then drip the aqueous solution (containing 15 weight parts of deionized water) containing 5 weight parts of acrylic acid, 0.6 weight parts of sodium methacrylate sulfonate, 0.3 weight parts of vitamin C, and control it to finish dripping in 3 hours; After finishing, stirring and reacting at room temperature for 1 hour, the anti-seawater erosion concrete admixture (K1) is obtained.

Example 2

A kind of anti-seawater erosion fair-faced concrete admixture, the preparation method of which comprises the following steps:

4 parts by weight of acrylamide, 3 parts by weight of diethylenetriaminomethyloxysilane and 75 parts by weight of deionized water were added to the reaction kettle; Sodium was added to the reactor at one time, and then an aqueous solution (containing 10 parts by weight of deionized water) containing 5.5 parts by weight of acrylic acid, 0.7 parts by weight of sodium methacrylate sulfonate, and 0.25 parts by weight of vitamin C was added dropwise, and it was controlled to drip in 3.5 hours. Finished; after dripping, stirring and reacting at room temperature for 1 hour, the anti-seawater erosion concrete admixture (K2) was obtained.

Example 3

A kind of anti-seawater erosion fair-faced concrete admixture, the preparation method of which comprises the following steps:

6 parts by weight of acrylamide, 3 parts by weight of vinyltrimethyloxysilane and 72 parts by weight of deionized water were added to the reactor; then under stirring conditions and a temperature of 40 ° C, 0.4 parts by weight of potassium persulfate was once Join in the reaction kettle, then drip the aqueous solution (containing 14 parts by weight deionized water) containing 4 parts by weight of acrylic acid, 0.6 parts by weight of sodium methacrylic acid sulfonate, 0.3 parts by weight of vitamin C, and control it to drip in 3 hours; drip; After finishing, stirring and reacting at room temperature for 1.5 hours, the anti-seawater erosion concrete admixture (K3) is obtained.

Example 4

A kind of anti-seawater erosion fair-faced concrete admixture, the preparation method of which comprises the following steps:

3.5 parts by weight of acrylamide, 2 parts by weight of γ-aminopropyltrimethoxysilane and 77 parts by weight of deionized water were added to the reactor; then under stirring conditions and a temperature of 35°C, 0.35 parts by weight of ammonium persulfate was added. Add it to the reactor at one time, and then dropwise add the aqueous solution (containing 13 parts by weight of deionized water) containing 6 parts by weight of acrylic acid, 0.65 parts by weight of sodium methacrylic acid sulfonate, and 0.35 parts by weight of vitamin C, and control it to drip in 3.5 hours. ; After dripping, stirring and reacting at room temperature for 1.5 hours, the anti-seawater erosion concrete admixture (K4) is obtained.

Example 5

A kind of anti-seawater erosion fair-faced concrete admixture, the preparation method of which comprises the following steps:

5 parts by weight of acrylamide, 3 parts by weight of methylaminopropyltrimethoxysilane and 79 parts by weight of deionized water were added to the reactor; then under stirring conditions and a temperature of 25°C, 0.4 parts by weight of sodium persulfate was added. Add it to the reactor at one time, and then dropwise add the aqueous solution (containing 8 parts by weight deionized water) containing 4.5 parts by weight of acrylic acid, 0.6 parts by weight of sodium methacrylic acid sulfonate, and 0.3 parts by weight of vitamin C, and control it to drip in 3 hours. ; After dripping, stirring and reacting at room temperature for 1.5 hours, the anti-seawater erosion concrete admixture (K5) is obtained.

The seawater-erosion-resistant fair-faced concrete admixtures obtained in Examples 1-5 of the present invention were applied to concrete, and combined with two commercially available seawater-erosion-resistant concrete admixtures (Nantong Ruirui Waterproof New Technology Development Co., Ltd. FLW-99 organosilicon waterproofing agent). A is compared with the UC-420 polyether polymer concrete viscosity modifier B) produced by Wuhan Youcheng Technology Co., Ltd. The mixing ratio of the concrete is shown in Table 1, and then referring to GB/T50080-2016 "Ordinary Concrete Mixtures" Performance Test Method Standard", JGJ/T283-2012 "Technical Specification for Self-compacting Concrete Application" and GB/T50082-2009 "Standard for Long-term Performance and Durability Test of Ordinary Concrete" and other standards, the strength of the obtained concrete, chloride ion diffusion coefficient 100mm*100mm*100mm concrete specimens that have been cured for 28 days are used to cut 100mm*100mm*20mm sheet samples, and use a mill For the polished samples, a digital microhardness tester was used to test the microhardness of the interface transition zone. Finally, the average value of 10 groups of data was taken as the microhardness value of the sample; the specific test results are shown in Table 2.

Table 1 Concrete mix ratio

Table 2 Concrete performance test results

The above results show that the application of the anti-seawater erosion-resistant fair-faced concrete admixture obtained by the present invention to concrete can effectively improve the slurry stability of the concrete mixture, improve the hardness of the interface transition zone, reduce the diffusion performance of chloride ions, and improve the corrosion resistance of concrete. and the reaction conditions involved in the present invention are mild, the process is simple, environmentally friendly and efficient, and is suitable for a large-scale industrial production method.

The above-mentioned embodiments are only for the purpose of clearly illustrating the examples, and are not intended to limit the implementation. For those of ordinary skill in the art, other different forms of changes or changes can also be made on the basis of the above description, and it is not necessary and impossible to list all the implementations here, so the obvious changes or changes implied It still falls within the protection scope of the present invention.

Claims (5)

1. A seawater erosion clear-water concrete admixture, each component and its parts by weight include: 3-6 parts of unsaturated carboxylic acids, 3-6 parts of unsaturated carboxylic acid derivatives, 0.3-0.7 parts of unsaturated sulfonic acids parts, 1-4 parts of silane coupling agent, 0.2-0.6 parts of initiator, 0.15-0.5 parts of vitamin C, 85-95 parts of water; The unsaturated carboxylic acid is one or both of acrylic acid and methacrylic acid; The unsaturated carboxylic acid derivative is acrylamide; Its preparation method comprises the following steps: 1) Weigh each raw material by proportion, each raw material and its share by weight include: 3-6 parts of unsaturated carboxylic acid, 3-6 parts of unsaturated carboxylic acid derivatives, 0.3-0.7 part of unsaturated sulfonic acid, silane 1-4 parts of coupling agent, 0.2-0.6 part of initiator, 0.15-0.5 part of vitamin C, 85-95 parts of water; 2) Add the weighed unsaturated carboxylic acid derivative, silane coupling agent and water into the reaction kettle; then under stirring conditions, control the temperature at 10-40 ° C; add initiator, and under stirring conditions, dropwise Add the aqueous solution containing unsaturated carboxylic acid, unsaturated sulfonate and vitamin C, and control the dripping within 2.5 to 3.5 hours; after dripping, stir and react at room temperature for 1 to 1.5 hours, that is, the anti-seawater erosion fair-faced concrete is obtained. agent. 2. The described seawater erosion concrete admixture according to claim 1, is characterized in that, described unsaturated sulfonate is sodium methacrylate. 3. the described seawater erosion concrete admixture according to claim 1, is characterized in that, described silane coupling agent is aminopropyltrimethoxysilane, diethylenetriaminomethyloxysilane, vinyl One or more of trimethyloxysilane, vinyl(2-methylethoxy)silane and γ-aminopropyltrimethoxysilane. 4. the described seawater erosion concrete admixture according to claim 1, is characterized in that, described initiator is one or more in hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate. 5. the preparation method of the anti-seawater erosion concrete admixture described in any one of claim 1～4, is characterized in that, comprises the steps: 1) Weigh each raw material by proportion, each raw material and its share by weight include: 3-6 parts of unsaturated carboxylic acid, 3-6 parts of unsaturated carboxylic acid derivatives, 0.3-0.7 part of unsaturated sulfonic acid, silane 1-4 parts of coupling agent, 0.2-0.6 part of initiator, 0.15-0.5 part of vitamin C, 85-95 parts of water; 2) Add the weighed unsaturated carboxylic acid derivative, silane coupling agent and water into the reaction kettle; then under stirring conditions, control the temperature at 10-40 ° C; add initiator, and under stirring conditions, dropwise Add the aqueous solution containing unsaturated carboxylic acid, unsaturated sulfonate and vitamin C, and control the dripping within 2.5 to 3.5 hours; after dripping, stir and react at room temperature for 1 to 1.5 hours, that is, the anti-seawater erosion fair-faced concrete is obtained. agent.