What is the pozzolanic effect in cement

Hello landlord, let's start with volcanic ash.

Speaking of the pozzolana mixture in the cement. In some pozzolana mixtures, a certain amount of active silica is present.

Active ingredients such as activated alumina. The so-called volcanic ash reaction refers to the combination of these active components with calcium hydroxide.

reaction to generate hydrated calcium silicate, hydrated calcium aluminate or hydrated calcium sulfoaluminate and other reaction products, among which, calcium hydroxide can be mixed with lime, or calcium hydroxide released when cement is hydrated.

In the process of hydration of pozzolana cement, the pozzolana reaction is the active component in the pozzolane mixture with the cement clinker.

Reaction of calcium hydroxide released during hydration. Therefore, the hydration process of pozzolana cement is a secondary reaction process. This is followed by the hydration of the cement clinker, which releases calcium hydroxide, followed by the pozzolanic ash reaction.

These two reactions are alternate and conditioned and conditioned each other, rather than simply isolated.

However, the reaction time of volcanic ash is relatively long, if the environment is too dry, when the concrete is shown to be short of water, the volcanic ash can not fully react, which directly causes the concrete strength to increase slowly, and even leads to insufficient strength in serious cases.

The "active effect" of fly ash is also called "volcanic ash effect" because fly ash is an artificial volcanic ash material.

Because the chemical components in fly ash contain a large amount of active SiO2 and Al2O3, it reacts chemically with alkaline substances such as Ca(OH)2 in a humid environment to generate cementitious substances such as calcium silicate hydrate and calcium aluminate hydrate, which can play a role in enhancing fly ash products and concrete, block the capillary structure in concrete, and improve the corrosion resistance of concrete.

The volcanic ash effect, which refers to the social impact of a large volcanic eruption caused by volcanic ash on the environment, is also described as the "butterfly effect". Because volcanic ash first causes the suspension of air transportation, it affects the operation of part of the economy; Large amounts of volcanic ash can also lead to changes in the climate and environment, which in turn will affect people's lives, and so on.

The Icelandic volcano, which paralyzed Europe's air traffic, is still erupting in full force and accompanied by thunder and lightning. Since the eruption on April 14, 2010, volcanic smoke and dust have gradually covered parts of Europe, paralyzing air traffic in large areas. The impact of this incident has spread from the European region to all corners of the world, and the scope of the incident has also spread to all aspects of social production and life, such as politics, economy, science and technology.

The volcanic ash effect (i.e., the active effect) of fly ash

Silicate vitreous bodies such as SiO2 and A L2O3 in fly ash react with cement and lime to produce alkaline activator Ca(OH)2 after mixing water to generate hydrated calcium silicate and other gels, which play a reinforcing role in mortar. The active effect of fly ash refers to the chemical effect produced by the active ingredient of fly ash. If fly ash is used as a gelling component, this effect is naturally the most important fundamental effect.

The products of fly ash hydration reaction are cross-connected on the surface of fly ash glass beads, which plays an important role in promoting the strength growth of mortar or concrete, especially the growth of tensile strength.

Common concrete inclusions, slag, etc., all have this effect.

Summary. Kiss, pozzolana cement refers to natural or artificial mineral materials containing activated silicon oxide and activated alumina, which are mixed with lime and water after grinding into fine powder, which can not only harden in the air, but also continue to harden in water, which is called pozzolana mixed material, which has the dual properties of glass phase and microcrystalline phase. Originally, volcanic ash refers to the vitreous material formed by the magma ejected from the ground by volcanic eruptions, which is cold due to low ground temperature and low pressure, and later it was found that after mixing the "volcanic ash" ejected during volcanic eruptions, lime can not only harden in air, but also harden in water, obtaining hydraulic properties similar to ordinary cement.

This shows that the pozzolana mixed material is an active mixed material, which can be used as a mixed material of Portland cement to make pozzolana Portland cement and fly ash Portland cement.

Kiss, pozzolana cement chauffeur refers to natural or artificial mineral materials containing activated silicon oxide and activated alumina, which are mixed with lime and water after grinding into fine powder, which can not only harden in the air, but also continue to harden in water, which is called pozzolana mixed material, which has the dual properties of glass phase and microcrystalline phase. Originally, volcanic ash refers to the vitreous material formed by the magma ejected from the ground by volcanic eruptions, which is cold due to the low temperature and low pressure of the ground, but later it was found that after mixing the "volcanic ash" ejected during volcanic eruptions, it can not only harden in the air, but also harden in water, obtaining hydraulic properties similar to ordinary cement. This shows that the pozzolana mixed material is an active mixed material, which can be used as a mixed material of Portland cement to make pozzolana Portland cement and fly ash silicate mud.

So much. The extra-clear denier of porosyl Portland cement is: strong water resistance, low heat of hydration, fast growth of strength in the later stage, resistance to sulfate corrosion, and good uniformity.

Its lack of silver is that it has low strength in the early days, and when it is low humidity, the strength grows very slowly. Answer: Therefore, it is not suitable for construction below 8.

Frost resistance and abrasion resistance are poor, and attention should be paid to strengthening the sprinkling cover and maintenance when using.

Kiss, typing also takes time.

Volcanic ash is a clean and environmentally friendly material, and crushing and adding volcanic ash to the mixture not only makes the process more environmentally friendly, but also makes the resulting structure stronger. Reducing the Congming volcanic ash particles to a size of about 6 micro-denier Zheng nuclear meters greatly increases its strength by creating more surface area for water and cement to bond together. Therefore, pozzolana cement has better performance and higher application value than volcanic molded ash cement.

Pozzolana cement is a commonly used building material, which has certain advantages, such as high strength, good compressive performance, strong durability, etc. However, it also has some drawbacks, and here are some of the drawbacks that may have a good time:

1.The color of the concrete is dark and unsightly. Pozzolana cement is darker in color and not as light as regular cement, which may affect the appearance of the building.

2.The hardening time is longer. Compared to ordinary cement, pozzolana cement takes longer to harden and takes longer to reach design strength.

4.**Higher. Compared with ordinary cement, the ** of the cement of the collapse of the volcanic ash is higher, which may increase the construction cost.

In general, although pozzolana cement has some disadvantages, it is still a useful building material in some special construction occasions.

Pozzolana cement is a kind of cement product with volcanic rock, mineral ash slag and other main raw materials, which has certain advantages over ordinary cement, but also has the following disadvantages:

1.**Higher: Because the production raw materials and manufacturing process costs of pozzolanic cement are higher than those of Kainaxiao, it is also higher than that of ordinary cement.

2.Uneven quality: The quality of pozzolana cement is uneven, and factors such as not strictly controlling the temperature during the production process may affect the quality of the product.

3.Durability is not enough: Compared with ordinary cement, the compressive strength and crack resistance of pozzolana cement are slightly inferior, especially in humid and high salinity environments, and it is easy to crack and weather.

4.Difficult to produce: The raw material acquisition and manufacturing process of pozzolana cement is relatively complex, and the production is difficult, so it is difficult to increase the output significantly, and it may be difficult to meet the needs of large-scale projects.

There are three main disadvantages of pozzolana cement:

First of all, the strength and compressive performance of pozzolana cement are worse than that of ordinary cement, and it cannot withstand too much limb force.

Secondly, the durability of pozzolana cement is poor, and it is easy to be eroded by rain and water, so it cannot be used for a long time.

Finally, the price of pozzolane cement is high and cannot meet the needs of most consumers.

There are three main disadvantages of pozzolana cement:

1. High firing cost: Since the melting point of pozzolane cement is higher than that of ordinary cement, the firing cost is higher;

2. Low hardness: pozzolan cement has a low melting point because of its special low melting point, so the hardness is also low, and it is easy to be affected by environmental temperature changes;

3. Poor durability: The objects made of pozzolana cement have poor durability and are easily affected by changes in the external environment, and the compressive resistance is not strong enough for lead.

You are asking "what are the characteristics of slag cement, pozzolana cement and fly ash cement?" ”。Their characteristics are as follows:

1. Slag cement: Slag cement is made of slag, limestone and silica, etc. It has the advantage of high silicate content and high compressive strength.

2. Arcanic cement: The old cement of the fire limb is made of volcanic ash and limestone. It has the advantage of high early strength and good resistance to sulfate attack.

3. Fly ash cement: Fly ash cement is made of fly ash and limestone produced in coal mines, thermal power generation and other industries. Its advantages are high strength and low starvation contraction.

Summary. The difference in the type of mixed material, and thus the performance is slightly different, such as:

Slag cement generally has a small heat of hydration, is used for large-volume projects, is not prone to concrete expansion and cracking, and its sulfate resistance is slightly better.

The properties of fly ash cement are close to those of slag cement.

The maximum of ordinary cement mixture is not more than 20%, and the minimum mark is that, so more sand and gravel can be added when used;

The mixture of slag cement and fly ash cement must be higher than 20%, and the minimum mark is, so the use of sand and gravel is usually less than that of ordinary cement.

It can be said that ordinary cement is better used for important projects (except for dams, nautical mile projects, etc.), while slag cement and fly ash cement are generally used for ordinary construction, anti-sulfur and other projects. Of course, for those with high sulfur resistance, sulfate-resistant cement must be used, and for dams, it is best to use medium- or low-heat cement.

What are the differences in the reaction of coal gangue mixture volcanic ash under different cement contents.

For example, slag cement generally has a small heat of hydration, which is used for large-volume projects, and is not prone to concrete expansion and cracking, and its sulfate resistance is slightly better. The properties of fly ash cement are close to those of slag cement.

The maximum of ordinary cement mixture is not more than 20%, and the minimum mark is that, so more sand and gravel can be added when used; The mixture of slag cement and fly ash cement must be higher than 20%, and the minimum mark is, so the use of sand and gravel is usually less than that of ordinary cement. It can be said that ordinary cement is better used for important projects (except for dams, nautical mile projects, etc.), while slag cement and fly ash cement are generally used for ordinary construction and construction, and projects requiring leather rackets such as sulfur resistance for Rankaixian. Of course, for those with high sulfur resistance, sulfate-resistant cement must be used, and for dams, it is best to use medium- or low-heat cement.

Why is there a great difference in the morphology of the volcanic ash reaction of the coal gangue mixture under different cement contents.

Yours is not what I'm asking about [eating whales].

The content of the ingredients varies.

I also know that the cement content is different, so I asked why the different cements lead to differences in the morphology of SEM.

In general SEM, the sample needs to be observed under high vacuum conditions, and when observing under low vacuum or humid conditions, variable pressure or environment or such as SEM, orange mass attack and low or high temperature observation of round brother requires special instruments.

Sidestep the question. Still haven't explained.

It is not the same as the degree of SEM reaction.

Hope it helps, dear

Summary. Good evening, kiss <>

than the heart] <>

Is it true or wrong that volcanic ash is a good building material.

Good evening, kiss <>

than the heart] <>

Is it right or wrong that volcanic ash is a good building material"Dear, volcanic ash is a good building material.

The original hail is a powdery substance that is accompanied by magma erupting on the surface of the earth, which has the characteristics of seepage and looseness, which is not suitable for building materials.

Volcanic ash is like dust, and it can't be used as a building material, but it can be used as soil for planting.

In general, volcanic eruptions are surrounded by volcanic ash, which is very important for the development of the plantation industry.