What are the effects of concrete anti-segregation agents on cement?

Contents of this article

• The best formula for concrete anti-segregation agent?

• Can adding anti-permeability agent to c30 concrete prevent cracking?

• What is cement stabilizer?

• What is the impact of flocculant in artificial sand on concrete?

• Can concrete cellulose powder be used as a roof?

• What are the effects on the performance of cement concrete after adding retarder?

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 to 90mm to the current slump of 180 to 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 in a large flow state. 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 machine-made 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.

Can adding anti-penetration agent to c30 concrete prevent cracking?

There is an inseparable dialectical relationship between concrete anti-cracking and anti-permeability, and actual projects cannot deviate from this relation. The establishment of the latest anti-cracking concept of concrete with high permeability and anti-cracking takes advantage of this relationship. After the concrete is poured and formed, the mixing water must not be lost, and perfect wet curing should be used to prevent water loss defects.

This is the only way to follow the laws of concrete development and link the crack resistance and seepage resistance of concrete.

If concrete is allowed to lose water in the early stage of hardening, it will resist cracking but not seepage, which deviates from the inseparable dialectical relationship between crack resistance and seepage resistance. It is the root cause of the common problems of cracking and seepage quality in concrete projects for a long time

What is cement stabilizer?

Cement stabilizers are also called tackifiers, plastic retaining agents, water retaining agents, etc. Adding thickeners to cement can increase the viscosity of the aqueous solution when the dosage is low.

By ��The free water in the cement slurry is restrained, so that the gaps between the cement particles are preserved, the friction between the particles is reduced, and the mixture is easily deformed. As the viscosity increases, the cohesion increases accordingly, so the segregation resistance of the cement is greatly improved.

What is the impact of flocculant in artificial sand on concrete?

Flocculants in artificial sand can cause solutes, colloids or suspended particles in aqueous solutions to produce flocculent precipitation, thereby purifying water quality. Therefore, currently sand and gravel production companies widely use flocculants to treat The sand washing water is purified, filtered and recycled again. However, sand and gravel production companies only consider that the discharge of sand and gravel washing water meets environmental protection requirements, but do not consider that the recycled sand and gravel washing water contains a large amount of flocculant, which will be brought into the machine-made sand and gravel, affecting the quality of concrete.

(1) Flocculant will affect the external pumping dosage and the workability of concrete. The greater the flocculant dosage, the more serious the impact will be on the pumping agent dosage and concrete workability.

(2) Low dosage of flocculant can improve the cohesion and strength of concrete.

(3) When the polyacrylamide content with an anionic molecular weight of 12 million is less than 0.02‰ of the sand content, it will not affect the pumping agent content and concrete workability, and the loss over time is normal after 3 hours. , it will also improve the workability of concrete; low dosage of flocculant can also improve the strength of concrete.

(4) When the dosage of polyacrylamide with an anionic molecular weight of 12 million is higher than 0.02‰, the dosage of pumping agent will increase with the increase of its dosage, and the concrete will be easy to The performance will decrease as its dosage increases.

(5) The addition of polyacrylamide with an anionic molecular weight of 8 million will affect the dosage of pumping agent and the workability of concrete.

Can concrete cellulose powder be used as a roof?

It is best not to, 1. The price-performance ratio is average, and the safety is not guaranteed

If you look at the fibers inside the fiber cement board, those made of asbestos fiber are also called asbestos cement boards. , this is not a very environmentally friendly material, it contains carcinogens and is unsafe. If it does not contain asbestos fibers and uses paper pulp, wood chips, or glass fiber, although it is more environmentally friendly, it is expensive and not very strong.

2. Space occupied area

Cement fiber board is also a kind of wall decoration material. When decorating the wall in a small house, it will take up part of the space, making it Residents feel that it is quite crowded, and the ceiling insulation and sound insulation functions are limited

What are the effects on the performance of cement concrete after adding a retarder?

1. Retarder is a commonly used admixture used to extend the setting time of concrete. In summer construction, adding an appropriate amount of retarder can make fresh concrete maintain better quality for a long time. Plasticity.

2. Retarder is a surfactant that only plays a physical adsorption and dispersion role in concrete, but does not directly participate in the cement hydration reaction to generate new substances. Therefore, it is suitable for use within a certain dosage range. It has no direct impact on the final strength of concrete, but because it delays the setting time of concrete, it affects the early strength of concrete to a certain extent. However, the later strength can generally catch up with or exceed that of concrete without retarder.

With the rapid development of commercial concrete today, retarder plays a very important role. As people's understanding of retarder continues to deepen, the application of retarder will become more and more extensive, especially when producing large-volume concrete that needs to reduce the instantaneous hydration heat of cement and delay the peak hydration of cement. Agents are indispensable.