阅读说明：本技术 一种清水混凝土专用外加剂及其制备方法 (Admixture special for fair-faced concrete and preparation method thereof ) 是由 邓妮 陈杰 方世昌 田应兵 于 2020-12-03 设计创作，主要内容包括：本发明公开了一种清水混凝土专用外加剂及其制备方法,所述外加剂包括以下组份的原材料组成：减水剂30%～35%、引气剂0.02%～0.05%、消泡剂0.04%～0.08%、缓凝剂1.8%～2.5%、阻锈剂1%～3%、防水增强剂2%～4%、减缩剂1%～2%和水55%～60%,本发明制备的清水混凝土专用减水剂,在分子结构设计上引入肉桂酰胺,降低了减水剂对无机盐的敏感性,保持其伸展构象,同时具有良好的早强效果,本发明的清水混凝土外加剂,原料易得,工艺简单,其中专用减水剂的制备操作简便安全,易规模生产化,可实现对清水混凝土外加剂成本的进一步控制。(The invention discloses a special admixture for fair-faced concrete and a preparation method thereof, wherein the admixture comprises the following raw materials: the water reducing agent is 30-35% of a water reducing agent, 0.02-0.05% of an air entraining agent, 0.04-0.08% of a defoaming agent, 1.8-2.5% of a retarder, 1-3% of a rust inhibitor, 2-4% of a waterproof reinforcing agent, 1-2% of a shrinkage reducing agent and 55-60% of water.)

1. The admixture special for the fair-faced concrete is characterized in that: the additive comprises the following raw materials: 30-35% of water reducing agent, 0.02-0.05% of air entraining agent, 0.04-0.08% of defoaming agent, 1.8-2.5% of retarder, 1-3% of rust inhibitor, 2-4% of waterproof reinforcing agent, 1-2% of shrinkage reducing agent and 55-60% of water.

2. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the water reducing agent is a polycarboxylate water reducing agent with the solid content of 45%, and the preparation method comprises the following steps:

1) putting the mixture of unsaturated polyoxyethylene ether and water into a reaction kettle, and uniformly stirring until no obvious blocks or sheets exist in the mixed solution; the unsaturated polyoxyethylene ether is one or two of isoamylol polyoxyethylene ether and modified isoamylol polyoxyethylene alcohol, and the number average molecular weight is 2400; the mass ratio of the unsaturated polyoxyethylene ether to the water is 0.75-0.91;

2) preparing A, B liquid;

solution A: acrylic acid, cinnamamide, a reducing agent 1 and water;

solution B: reducing agent 2+ chain transfer agent + water;

the mass of the acrylic acid is 7-8.5% of that of the unsaturated polyoxyethylene ether; the weight of the cinnamamide accounts for 1% -2% of that of the unsaturated polyoxyethylene ether; the reducing agent 1 is vc, the reducing agent 2 is sodium formaldehyde sulfoxylate, and the total consumption of the reducing agent is 3-6 per mill of the total mass of the polyether and the acrylic acid; the chain transfer agent is at least one of sodium mercaptopropionate and sodium thioglycolate, and the sodium mercaptopropionate and the sodium thioglycolate are respectively generated by neutralization reaction of sodium hydroxide before use;

adding a metal catalyst and an initiator into the bottom liquid of the kettle, stirring for 5-10 min, and then simultaneously dropwise adding A, B liquid; the dripping time of the solution A is 150-180 min, and the dripping time of the solution B is 150-180 min;

after the dropwise adding is finished, preserving heat for 1-1.5 h, then adding a sodium hydroxide solution, adjusting the pH value to 6-7, and supplementing water until the concentration is 45%;

wherein the metal catalyst is ferrous sulfate; the initiator is hydrogen peroxide or ammonium persulfate, and the total mass of the initiator is 5-8 per mill of the total mass of the polyether and the acrylic acid.

3. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the retarder is a mixture of sodium gluconate, white sugar and molasses, and the mass ratio of the sodium gluconate to the white sugar to the molasses is 3:1: 1.

4. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the defoaming agent is polyether organic silicon.

5. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the air entraining agent is at least 1 of maleated rosin, sodium dodecyl benzene sulfonate and triterpenoid.

6. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the rust inhibitor is composed of calcium nitrite and sodium hexametaphosphate.

7. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the waterproof agent is an alkaline silica sol solution with the mass fraction of 30%.

8. The admixture special for fair-faced concrete according to claim 1, which is characterized in that: the shrinkage reducing agent is at least 1 of polyethylene glycol 200-400, butanol and polyethylene glycol monomethyl ether acrylate.

9. The admixture special for fair-faced concrete and the preparation method thereof as claimed in claim 1, wherein the preparation method comprises the following steps: firstly weighing a water reducing agent, firstly adding water, then sequentially adding a retarder, a rust inhibitor, a defoaming agent, a shrinkage reducing agent and a waterproofing agent, uniformly stirring, and then adding an air entraining agent and water to obtain the chemical admixture for the fair-faced concrete.

Technical Field

The invention relates to the field of building materials, in particular to an admixture for fair-faced concrete.

Background

The fair-faced concrete is also called decorative concrete, different from the common concrete which needs to be further surface-decorated, the fair-faced concrete directly adopts the natural surface effect of cast-in-place concrete as a facing, thereby saving the use of chemical products such as paint, facing and the like; meanwhile, the clean water concrete structure is formed in one step, chiseling and repairing are not needed, plastering is not needed, and a large amount of construction waste is reduced. In recent years, with the enhancement of environmental awareness and the unique aesthetic appearance of strength, cleanness, material feeling and the like of the fair-faced concrete structure, the fair-faced concrete works are more and more popular with people, and are not only widely applied to large buildings such as large bridges, plants and airports, but also applied to certain industrial and civil buildings.

The performance requirement of the fair-faced concrete is higher than that of the common concrete, and the fair-faced concrete requires the concrete to have accurate appearance size and no obvious macroscopic defects on the surface. Therefore, the types and addition amounts of the additives are main factors directly influencing the performance of the fair-faced concrete besides the basic concrete components. The polycarboxylic acid high-performance water reducing agent is one of the most commonly used concrete admixtures at present because of the excellent properties of low mixing amount, high water reducing rate, strong molecular structure adjustability, environmental protection and the like, and is widely applied to various projects. However, the performance of the common polycarboxylic acid water reducing agent is more biased to the water reducing rate, and if the polycarboxylic acid water reducing agent is independently applied to fair-faced concrete, the finally obtained fair-faced concrete is easy to have the apparent quality problems of more surface bubbles, pitted surfaces, honeycombs, serious color difference and the like, so that when the polycarboxylic acid water reducing agent is applied to the fair-faced concrete, other additives are required to be compounded for use, and in addition, the performance characteristics of the water reducing agent are also required to be optimized and adjusted. For example, in patent "a low bleed air type fair-faced concrete admixture and preparation method thereof" with publication number CN 1097760621 a, dibutylene glycol maleate, higher aliphatic alcohol methacrylate, crosslinking monomer and EO/PO random copolymerized acrylate monomer are copolymerized to obtain a low bleed air type polycarboxylic acid water reducing agent, which reduces the air content of concrete to a certain extent, reduces the generation of bubbles, and improves the apparent quality of fair-faced concrete, but the water reducing and slump retaining performance of the low bleed air type water reducing agent is affected to a certain extent, and the water reducing agent has high cost, complex production process, and difficult control of the stability of the product. The bare concrete admixture provided in the patent with the publication number of CN108545988, namely the admixture special for bare concrete and the preparation method thereof, and the bare concrete and the application thereof, is simple and practical to prepare, but does not clearly indicate the main components of each additive component. Because each component has too many varieties of substances and great difference of action and effect, the technical effect expected in the patent is difficult to achieve by random matching and use without limitation, and at present, the research on the admixture specially used for the water-thinned concrete is lack of systematic research. Most patent documents are optimized and adjusted for performance in some aspect, but the working performance, apparent mass, durability, cost and the like are not comprehensively considered.

Disclosure of Invention

The invention aims to: aiming at the problems, the fair-faced concrete admixture has excellent comprehensive performance, simple preparation method, easy realization of large-scale production and industrial application and economic advantages.

In order to achieve the purpose, the invention provides the following technical scheme: the admixture special for the fair-faced concrete comprises the following raw materials: 30-35% of water reducing agent, 0.02-0.05% of air entraining agent, 0.04-0.08% of defoaming agent, 1.8-2.5% of retarder, 1-3% of rust inhibitor, 2-4% of waterproof reinforcing agent, 1-2% of shrinkage reducing agent and 55-60% of water.

Preferably, the water reducing agent is a polycarboxylic acid water reducing agent with the solid content of 45%, and the preparation method comprises the following steps:

1) putting the mixture of unsaturated polyoxyethylene ether and water into a reaction kettle, and uniformly stirring until no obvious blocks or sheets exist in the mixed solution; the unsaturated polyoxyethylene ether is one or two of isoamylol polyoxyethylene ether and modified isoamylol polyoxyethylene alcohol, and the number average molecular weight is 2400; the mass ratio of the unsaturated polyoxyethylene ether to the water is 0.75-0.91;

2) preparing A, B liquid;

solution A: acrylic acid, cinnamamide, a reducing agent 1 and water;

solution B: reducing agent 2+ chain transfer agent + water;

the mass of the acrylic acid is 7-8.5% of that of the unsaturated polyoxyethylene ether; the weight of the cinnamamide accounts for 1% -2% of that of the unsaturated polyoxyethylene ether; the reducing agent 1 is vc, the reducing agent 2 is sodium formaldehyde sulfoxylate, and the total consumption of the reducing agent is 3-6 per mill of the total mass of the polyether and the acrylic acid; the chain transfer agent is at least one of sodium mercaptopropionate and sodium thioglycolate, and the sodium mercaptopropionate and the sodium thioglycolate are respectively generated by neutralization reaction of sodium hydroxide before use;

adding a metal catalyst and an initiator into the bottom liquid of the kettle, stirring for 5-10 min, and then simultaneously dropwise adding A, B liquid; the dripping time of the solution A is 150-180 min, and the dripping time of the solution B is 150-180 min. And (3) preserving heat for 1-1.5 hours after the dropwise adding is finished, then adding a sodium hydroxide solution, adjusting the pH value to 6-7, and supplementing water until the concentration is 45%. Wherein the metal catalyst is ferrous sulfate; the initiator is hydrogen peroxide or ammonium persulfate, and the total mass of the initiator is 5-8 per mill of the total mass of the polyether and the acrylic acid.

Preferably, the retarder is a mixture of sodium gluconate, white sugar and molasses, and the mass ratio of the sodium gluconate to the white sugar to the molasses is 3:1: 1.

Preferably, the defoamer is a polyether silicone.

Preferably, the air entraining agent is at least 1 of maleated rosin, sodium dodecyl benzene sulfonate and triterpenoid.

Preferably, the rust inhibitor is composed of calcium nitrite and sodium hexametaphosphate.

Preferably, the waterproof agent is an alkaline silica sol solution with the mass fraction of 30%.

Preferably, the shrinkage reducing agent is at least 1 of polyethylene glycol 200-400, butanol and polyethylene glycol monomethyl ether acrylate.

Preferably, the special admixture for fair-faced concrete and the preparation method thereof comprise the following steps: firstly weighing a water reducing agent, firstly adding water, then sequentially adding a retarder, a rust inhibitor, a defoaming agent, a shrinkage reducing agent and a waterproofing agent, uniformly stirring, and then adding an air entraining agent and water to obtain the chemical admixture for the fair-faced concrete.

The invention has the technical effects and advantages that:

(1) according to the performance requirements of the fair-faced concrete, the slump-retaining type polycarboxylate water reducer is synthesized by adopting the prenyl polyoxyethylene ether as a macromonomer under a low-acid-ether ratio and double-reduction system, has moderate water reducing rate, excellent slump-retaining performance and low doping sensitivity, has good wrapping property and cohesiveness of concrete mixtures, is not easy to cause segregation and bleeding, not only ensures the working requirements of the fair-faced concrete on fluidity and slump retentivity, but also plays a role in improving the surface quality of the fair-faced concrete.

(2) According to the special water reducing agent for the fair-faced concrete, the cinnamamide is introduced in the molecular structure design, so that the sensitivity of the water reducing agent to inorganic salt is reduced, the stretching conformation of the water reducing agent is kept, and meanwhile, the water reducing agent has a good early strength effect.

(3) Besides conventional sodium gluconate and white sugar, the retarder in the clear water concrete admixture is also added with a less-used retarder, namely molasses, and the three substances are matched and used according to a proper proportion, so that the requirement of the clear water concrete on the setting time is met, the flexibility of the concrete is increased, and the apparent quality of the concrete is further improved by clear water.

(4) The bare concrete admixture is compounded with multiple components on the basis of preparing the special polycarboxylic acid water reducing agent, and the additive components play a synergistic effect, so that the high requirement of bare concrete on the admixture is met, and the bare concrete admixture plays roles in protecting the bare concrete and improving the durability and safety of the bare concrete.

(5) The fair-faced concrete admixture has the advantages of easily obtained raw materials and simple process, wherein the preparation operation of the special water reducing agent is simple, convenient and safe, the scale production is easy, and the cost of the fair-faced concrete admixture can be further controlled.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The preparation method of the admixture special for the fair-faced concrete comprises the following steps:

1) special polycarboxylic acid water reducing agent for synthesis

Firstly, adding 300 parts of unsaturated polyoxyethylene ether and 220 parts of water into a reaction kettle, and uniformly stirring until no obvious blocks or sheets exist in the mixed solution; preparing solution A (22 parts of acrylic acid, 3g of cinnamamide, 22 parts of water and 0.2 part of VC) and solution B (1.3 parts of sodium formaldehyde sulfoxylate, 1.6 parts of sodium mercaptopropionate and 45 parts of water); then sequentially adding 2.5 parts of hydrogen peroxide and 1.4 parts of ferrous sulfate solution (1%) into the reaction kettle; and simultaneously dripping A, B solution at normal temperature, wherein the A solution is dripped at constant speed for 180min, and the B solution is dripped at constant speed for 180 min. And (3) preserving heat for 1h after the dropwise addition is finished, adding a sodium hydroxide solution, adjusting the pH value to 6-7, and supplementing water until the concentration is 45%.

Pouring 300g of the synthesized water reducing agent and 400g of water into a beaker, adding 22g of retarder and 20g of rust inhibitor, stirring until the water reducing agent and the rust inhibitor are dissolved, continuing to add 0.6g of defoaming agent, 30g of waterproofing agent and 15g of shrinkage reducing agent, stirring for 3-5 min, then adding 0.3g of air entraining agent and 220g of water, and continuing to stir uniformly to obtain the admixture special for the fair-faced concrete.

Example 2

The preparation method of the admixture special for the fair-faced concrete comprises the following steps:

1) special polycarboxylic acid water reducing agent for synthesis

Putting 320 parts of unsaturated polyoxyethylene ether and 230 parts of water into a reaction kettle, and uniformly stirring until no obvious blocks or sheets exist in the mixed solution; preparing solution A (23 parts of acrylic acid, 4g of cinnamamide, 24 parts of water and 0.2 part of VC) and solution B (1.4 parts of sodium formaldehyde sulfoxylate, 1.7 parts of sodium mercaptopropionate and 46 parts of water); then sequentially adding 2.5 parts of hydrogen peroxide and 1.4 parts of ferrous sulfate solution (1%) into the reaction kettle; and simultaneously dripping A, B solution at normal temperature, wherein the A solution is dripped at constant speed for 160min, and the B solution is dripped at constant speed for 160 min. And (3) preserving heat for 1.2 hours after the dropwise addition is finished, adding a sodium hydroxide solution, adjusting the pH value to 6-7, and supplementing water until the concentration is 45%.

And pouring 310g of the synthesized water reducing agent and 405g of water into a beaker, adding 23g of retarder and 21g of rust inhibitor, stirring until the water reducing agent and the rust inhibitor are dissolved, continuing to add 0.7g of defoaming agent, 32g of waterproofing agent and 16g of shrinkage reducing agent, stirring for 3-5 min, then adding 0.4g of air entraining agent and 225g of water, and continuing to stir uniformly to obtain the admixture special for the fair-faced concrete.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.