Concrete anti-segregation agent manufacturer-concrete segregation problems and treatment methods

Contents of this article

• The best formula for concrete anti-segregation agent?

• How to use anti-penetration agent?

• Concrete initial setting time and anti-freezing measures?

• Can urinary alkali dissolving agent wash stainless steel?

• After the concrete produced is poured into the company, frost will appear? I don’t know how to adjust the mix ratio to solve this problem! Please tell me?

• Concrete segregation problems and treatment methods?

What is the best formula for concrete anti-segregation agent?

Concrete, as the largest building material, has developed rapidly. In recent years, high-strength and high-performance concrete has been widely used in engineering. The fluidity of concrete has developed from the previous 70~90mm to the current slump of 180~230mm. Some projects also use self-compacting concrete, and the pumping height is getting higher and higher. However, the fluidity and cohesion of concrete are often incompatible, that is, it is difficult for concrete to maintain high cohesion properties under large flow conditions. In this way, concrete that pursues high fluidity is prone to bleeding and segregation. Moreover, with the gradual depletion of river sand resources and mineral resources in my country, the gradation and fineness of river sand fluctuate greatly, ordinary manufactured sand with poor particle size is used on a large scale, the water retention of cement fluctuates, and high water reduction but The more sensitive polycarboxylic acid-type water-reducing admixtures are constantly being promoted, and the quality control of ready-mixed concrete is facing increasingly severe challenges. The existing concrete anti-segregation agents have a strong flocculation effect, which will cause the concrete to settle quickly and the concrete to lose its flow properties instantly, which is detrimental to the workability of concrete. For this reason, we propose an anti-segregation agent for concrete and its preparation method.

Technical implementation elements:

The purpose of the present invention is to provide an anti-segregation agent for concrete and a preparation method thereof to solve the existing concrete anti-segregation problems proposed in the above background technology. The strong flocculation effect of the agent will cause the concrete to settle quickly, causing the concrete to lose its flow properties instantly, which is detrimental to the workability of the concrete.

In order to achieve the above object, the present invention provides the following technical solution: an anti-segregation agent for concrete, the composition of the anti-segregation agent for concrete is as follows:

Fly ash 5- 15 parts, mineral powder 5-15 parts, steel fiber 1-2 parts, polyethylene glycol 1-2 parts, polyhydroxy acid water reducing agent 20-30 parts, tackifier 0.8-1.2 parts, coagulant 0.5- 0.9 parts, 200-300 parts of deionized water, several parts of liquid alkali, 5-10 parts of silicone monomer, 3-5 parts of oxidizing agent, and 1-3 parts of reducing agent.

Preferably, the organosilicon monomer is propyltrichlorosilane or vinyltrichlorosilane or fluorosilicone monomer or a mixture of the three.

Preferably, the coagulant is powdered sodium sulfate.

Preferably, the tackifier is PAM, and the PAM is moistened with methanol or ethanol, deionized water is added for stirring, and the mixture is heated to 55 degrees Celsius during stirring to prepare a solution with a concentration of 4%.

Preferably, the oxidizing agent is one or a mixture of hydrogen peroxide, ammonium persulfate, and potassium persulfate.

Preferably, the reducing agent is ammonium persulfate-anhydrous sodium bisulfite or ammonium persulfate-sodium hypophosphite.

Preferably, the alkali solution is sodium hydroxide.

Preferably, the preparation method of the concrete anti-segregation agent includes the following steps:

S1: Mixing: combine silicone monomer, deionized water, polyhydroxyacid water-reducing agent and polyethylene glycol are added into the reaction kettle for mixing;

S2: Oxidation: Stir until the mixture in step S1 is evenly mixed, and add oxidant for oxidation;

S3: Reduction: Add fly ash, mineral powder and steel fiber to the oxidized mixture in step S2, and then add the reducing agent;

S4: Neutralization: Add a tackifier to the reduced mixture in step S3 and coagulant, stir continuously until the mixture is uniform, and then add liquid caustic soda to adjust the pH so that the pH is between 7-9, and then the anti-segregation agent for concrete can be obtained.

Compared with the existing technology, the beneficial effects of the present invention are: the invention adds fly ash, mineral powder and steel fiber to the anti-segregation agent, which can not only improve the compressive strength of concrete, but also It can also effectively improve the working performance and stratification of concrete, improve the segregation resistance of concrete, and reduce the expansion and slump of concrete. PAM is used as a tackifier because PAM has more -NH2. The tackifier has good hydrophilicity, making the concrete hydrophilic, water-retaining, thickening, resistance-reducing and viscosity-increasing. Adding calcium sulfate as a setting accelerator can promote concrete water splashing, accelerate hardening, and promote condensation. The invention has wide sources of raw materials, low cost, green and environmental protection, and simple operation.

How to use anti-penetration agent?

Impermeability agent can replace water when mixing concrete or mortar. During the reaction with the concrete or mortar layer, the atoms of its main component, the polymer compound, are connected into a linear network with longer branches. Anti-penetration agents generally have a three-dimensional structure distributed in random directions, densely distributed in the polymer structure of the concrete or mortar layer, and completely block the capillary channels of the concrete or mortar, making the cement and cement mortar hydrophobic and improving the anti-permeability ability of the concrete.

Concrete initial setting time and anti-freezing measures?

The initial setting time of concrete in winter is generally 8 to 12 hours, and the final setting time is 12 to 16 hours. If the temperature is below zero in winter (more than a week after pouring), just do a good job of concrete insulation. If concrete is poured in a negative temperature environment (temperature below minus 5°C), the main thing to pay attention to is the early stage.After mixing, place it in a cool place and let it dry naturally to see if the surface is frosted. Before plastering, a cost analysis of the plastering materials should be conducted to control the content of soluble salts, especially the content of K+ and Na+, and limit the use of soluble salt additives. This is key to preventing blooming. Try to use cement with low alkali metal oxide content and aggregates that do not contain soluble salts. Try not to use admixtures with high alkali metal oxide content. For concrete with high requirements for surface decoration, the Na2SO4 dosage should be less than 1% of the cement weight. If it is under unfavorable conditions that are prone to whitening and frosting, and in concrete with high decorative requirements on the surface, it is better not to add Na2SO4. When preparing concrete, add an appropriate amount of active siliceous admixtures, such as fly ash, silica fume, etc. Because they all contain a certain amount of SiO2, they can reduce the free alkali content in concrete. 2.2 Inhibition of chemical reactions Ca(OH)2 is one of the soluble substances that form frost, which can be achieved by incorporating admixtures or active materials, such as stearate, acrylate and other organic admixtures, first-class natural diatoms Soil, granulated slag, ultra-fine fly ash, silica fume, lithium carbonate, ammonium carbonate and adsorbent aggregates stabilize Ca(OH)2 with its chemical compounds or are adsorbed by the aggregates and no longer migrate to the building. surface, thereby achieving the purpose of preventing frost. In addition, when the concrete is curing, the drying speed can be slowed down so that the CO2 in the air has enough opportunities to enter the interior of the concrete from the tiny gaps and react with the dissolved Ca(OH)2 to form CaCO3, which remains in the concrete. inside the concrete to prevent frost. 2.3 Improve the impermeability of the base material When preparing concrete or mortar, the use of water reducing agents can reduce the mixing water consumption, thereby reducing the porosity of the concrete or mortar, improving the pore structure, and improving the impermeability performance. It can be said that as long as it can enhance the compactness of concrete or mortar and reduce cracking, admixtures containing less alkali metal oxides can be used, such as waterproofing agents, expansion agents, early strength agents, etc. The concrete or mortar should be vibrated and compacted, and the surface should be strengthened and plastered. It is best to plaster the surface again before initial setting to close the micro-cracks caused by water evaporation on the surface, dense the cement slurry floating layer, improve the surface impermeability, and strengthen maintenance. Spray a layer of waterproofing agent on the surface of concrete or mortar to seal the pores on the surface of concrete or mortar. 2.4 Hydrophobic treatment on the surface of the base layer Cement composite materials such as concrete, mortar and Portland concrete blocks are all hydrophilic materials. After the surface of the concrete or mortar is treated with a silicone hydrophobic agent, water cannot penetrate into the base material and can prevent Pan frost. Silicone hydrophobic agent is colorless and transparent, suitable for waterproofing treatment of cement colloid decorative boards, colored concrete (or mortar) and building surfaces with higher requirements. 3. Treatment after frost Since frost is diffusive, once frost is found on the surface of a building, measures should be taken as soon as possible. Otherwise, the frost area will continue to expand, increasing the degree of damage, and increasing the difficulty and cost of maintenance. The hoarfrost composed of water-soluble alkali metal salts (such as Na2SO4, K2SO4, K2CO3, Na2CO3, etc.) can be directly washed away with water. The white frost formed by the precipitation of CaCO3 cannot be washed away immediately with water. Small areas can be removed with fine sandpaper. For large areas of frost, sandblasting can be used. Use a sandblasting machine to spray dry fine sand on the frosted surface. It is best to remove it after treatment. Use silicone to treat the surface to be hydrophobic. This method can be used on plain walls or colored concrete (or mortar) surfaces. If water washing or sandblasting cannot remove the frost, pickling can be used. Building materials that are prone to frost are alkaline, and pickling will corrode the surface of the building, so this method should not be used unless absolutely necessary. The concentration of the acid should be as low as possible, generally oxalic acid or 1:1 dilute hydrochloric acid is used. Before cleaning, first wet the surface of the building to make its surface pores saturated with water (to prevent acid from entering the pores, causing blooming in the form of soluble salts, or penetrating into the interior to accelerate the corrosion of steel bars), and then clean with dilute acid. After removing the white frost, immediately rinse the surface thoroughly with clean water to prevent acid from remaining in the surface pores. After treatment, use silicone to treat the surface to be hydrophobic. For parts of the building surface that are severely frosted, which has caused loose structures, reduced strength, and surface peeling, it is not appropriate to use water washing, sandblasting or pickling methods, and physical methods should be used to eradicate them. That is, the non-dense frosted areas are dug out, densely filled with cement mortar with a low water-cement ratio and low alkali content, and the surface is smoothed to cut off the channels for water erosion, and finally the waterproof coating is applied.

Concrete segregation problems and treatment methods?

The main cause of concrete segregation problem is that it is stopped for too long without stirring, or the water-cement ratio is too high. Treatment method Generally speaking, the first phenomenon requires timely stirring and slump test. Normal construction can only begin after the slump test is suitable. If the water-cement ratio is too large, it is necessary to adjust the water consumption in time. It is best to have a tool or meter to measure the water volume.

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