What is the admixture in concrete?

Admixture: Concrete admixture is used to improve concrete performance, save water, and adjust the strength grade of concrete.

Natural or artificial powdered minerals are added to the concrete mixing process to improve the properties of the concrete. Admixtures can be divided into reactive admixtures and non-reactive admixtures. The active mineral admixture itself does not harden or hardens very slowly, but it can be hydrated with cement to form calcium oxide.

It reacts to generate hydration products with gelling ability, such as fly ash, granulated blast furnace slag powder, zeolite powder, silica fume, etc. In order to ensure the strength and slump of concrete.

Under the premise of requirements, the content of admixture and aggregate should be increased to reduce the amount of cement in unilateral concrete. Cement should be used as much as possible with low hydration heat and long setting time, and priority should be given to medium-heat Portland cement, low-heat slag Portland cement, dam cement, slag Portland cement, fly ash Portland cement, pozzolana Portland cement, etc. The non-reactive mineral admixture basically does not react with cement components, such as limestone and ground quartz sand.

and other materials. Commonly used coagulation admixtures include fly ash, granulated blast furnace slag, and pozzolacan. In particular, fly ash, ultra-fine granulated electric furnace slag, silica fume and other applications have good results. The active admixture is mixed with a superplasticizer.

In this case, it can increase the fluidity, cohesion, water retention and improve the pumpability of the concrete. And it can improve the strength and durability of hardened concrete. In engineering practice, the "double blending" technology is often adopted, that is, the superplasticizer is mixed with fly ash at the same time.

The ordinary, high-strength and high-performance concrete prepared in this way can save cement, improve the workability, strength and durability of concrete, and significantly reduce the volume of concrete.

Hydration heat can meet the construction technical requirements of different projects. <>

Admixtures used in concrete can be divided into two categories: reactive mineral admixtures and non-reactive mineral admixtures. Inactive mineral admixtures generally have no chemical interaction with cement components, or the chemical action is very small, such as finely ground quartz sand, limestone, hard slag and other materials. Although the active mineral admixture itself does not hydrate or the hydration rate is very slow, it can react with the Ca(OH)2 generated by cement hydration to form a cementitious material with hydraulic properties.

Such as granulated blast furnace slag, pozzolana materials, fly ash, silica fume, etc. The size of concrete water leakage is related to water consumption, water consumption is more, water leakage is large, in the selection of slag cement should try to choose the variety of water leakage, and should be mixed with water reducing agent in concrete to reduce water consumption. <>

Concrete admixture, adding a certain amount of admixture when preparing concrete, can improve the workability of fresh concrete, reduce the temperature rise inside the concrete, improve the strength in the later stage, and can optimize the internal structure of concrete, improve corrosion resistance, and the classification of admixtures: gelling admixtures such as hydraulic lime, etc.; pozzolana admixtures such as fly ash, etc.; Admixtures with gelling and pozzolana properties at the same time, such as high-calcium ash; Others, such as quartz sand, are chemically reactive materials. Improve the workability of concrete mixture, improve the mechanical properties and durability of concrete, save the amount of cement, reduce costs, adjust the setting and hardening speed of concrete, and improve the mesoscopic structure of concrete.

In order to improve the performance of concrete, save water, adjust the strength grade of concrete, and mix natural or artificial powdered minerals that can improve the performance of concrete when mixing concrete.

In addition to the above-mentioned four materials of cement, sand, stone and water, the composition materials of ordinary concrete can also add mineral mixed materials, that is, concrete admixtures.

According to the nature of the materials used, it can be divided into two types: reactive mixed materials and non-reactive mixed materials. The addition of mixed materials to cement can adjust the cement number and variety, increase cement output and reduce production costs; To a certain extent, improve some properties of cement to meet the special technical requirements of cement in construction projects; It can comprehensively utilize a large number of industrial waste residues, which is of great significance for environmental protection and energy saving.

What it does:

1) Adjust the cement number, so that the high-grade cement can be equipped with low-strength grade concrete, so as to meet the requirements of the specification for the minimum amount of cement in the concrete, so as to save cement.

2) It is used to increase the ash content in concrete, adjust the ash bone ratio, and improve plasticity, so as to improve the workability of the concrete mixture.

3) Use the different characteristics of various admixtures to improve the performance of concrete after hardening. For example, improve the impermeability, frost resistance, corrosion resistance and durability of concrete.

In the process of cement production, the mineral materials added to the cement in order to improve the performance of the cement and adjust the cement grade are called cement mixed materials, referred to as cement mixed materials.

Function: 1 Mixing mixed materials in cement can adjust the cement label and variety, increase cement output and reduce production costs.

2. To a certain extent, improve some properties of cement and meet the special technical requirements of cement in construction projects 3. A large number of industrial waste residues can be comprehensively utilized, which is of great significance for environmental protection and energy saving.

The artificial or natural mineral materials incorporated in the grinding of cement are called mixed materials. The mixed material can improve the performance of cement, adjust the cement grade, increase the cement output, and reduce the cost.

Excerpted from "Civil Engineering Materials", China Building Materials Industry Press.

Summary. Proportion and use of raw materials. The mixture is more suitable for making large building materials such as concrete and bricks, while the concrete is more suitable for building walls, floors, pavements and other places, as well as some small structures.

Proportion and use of raw materials. The mixture is more suitable for making concrete scion, bricks and other Dachang building materials, while concrete is more suitable for building walls, grounds, pavements and other places, as well as some small durable structures.

Can you tell us more about that?

A mixture is a mixture of multiple raw materials, usually including cement, sand, stones, water, etc. The main role of the mixture is to make concrete, bricks, building walls and other materials. The mixture can be adjusted according to different uses and strength requirements, and the specific posture resistance and blending method of the raw materials can be adjusted to achieve the desired performance and quality.

Concrete is a building material made up of cement, sand, gravel, and water, similar to a mixture. The difference is that the sand and gravel of concrete are finer than those of the mixture, the amount of cement is less, and the amount of water is much less old-fashioned. The main function of concrete is to be used in building walls, grounds, pavements and other places, as well as to make some small structures, such as flower beds, flower stands, etc.

Overall, the main difference between a mixture and a concrete is the proportion and use of the raw material. The mixture is more suitable for making large building materials such as concrete and bricks, while concrete is more suitable for building walls, floors, pavements and other places, as well as some small structures.

Mixtures and concrete are two materials commonly used in construction projects, and they are very different, which are described in detail below. Mixture is a composite material made by mixing natural or artificial aggregates, mineral admixtures, cementitious materials and other substances in a certain proportion. Mixtures are often used in construction to make pavement, masonry, and so on.

Concrete is an artificial stone made of aggregate (generally fine aggregate and coarse aggregate), cementitious material (cement, gypsum, etc.) and an appropriate amount of water mixed in a certain proportion. Concrete is often used in construction to make floors, foundations, and more. The main difference between the two is that the mixture is a composite material that includes a variety of basic materials, while concrete is an artificial stone composed of aggregate and cementitious material, and its main components are cement, aggregate, and water.

Secondly, the performance requirements such as the toughness of the mixture and the dust of the impermeable bridge are relatively low, while the performance requirements of concrete are high, such as meeting the standards of construction strength, durability, shrinkage, shrinkage, etc. When a problem like this needs to be solved, we can take the following steps:1

Problem analysis: Analyze the cause of the problem, such as the material properties of the mixture and the concrete, which lead to the difference in the final performance. 3.

Solution: For different problems, you need to take corresponding solutions. For example, in terms of mixtures, it is possible to change the ratio of materials and use additives; In terms of concrete, methods such as material ratio and quality control can be changed.

To sum up, although mixtures and concrete are both commonly used materials in construction projects, there are great differences in the properties of materials and the use of sensitive acres. Based on the understanding of the nature of these differences, we can take appropriate measures to ensure proper use in construction works.