What cement water heating is high, how much does the various cement hydration heat standards make

Portland cement has a high heat of hydration.

The heat emitted by the interaction of cement and water is called the heat of hydration and is expressed in joules (j g). The hydration reaction of cement is an exothermic reaction. As the hydration process progresses, the continuous release of heat is called hydrothermalization.

The size of the heat released by water heating and the speed of heat release are mainly related to the cement label.

Mineral composition is related to fineness.

The main factors influencing the heat of hydration are:

There are many factors that affect the heat of hydration of cement, including cement clinker.

Mineral composition, water-cement ratio.

Curing temperature, cement fineness, mixed material content and quality, etc., but mainly determined by the composition and content of clinker minerals. Among the main minerals of cement, the largest amount of heat released by complete hydration is C3A, followed by C3S, and then C4AF. Therefore, reducing the C3A content is beneficial to limit the heat of hydration of cement.

The high grade cement mineral composition is higher, the mineral purity is good, so the heat of hydration is high, and the greater the fineness, the larger the reaction area, so the water heating is high, sometimes the temperature also has a certain effect, the higher the temperature, the more intense the reaction.

For general construction and small-volume projects, the hydration heat of cement can be ignored, and the hydration hardening of cement can even be accelerated!

However, for large-volume projects, such as dams, bridges, etc., the heat of hydration cannot be released in time, and the more it accumulates, it will cause devastating consequences such as expansion and cracking! So there are special dam cement, low hydration heat cement! Some use other cooling methods!

Summary. For ordinary cement, the heat of hydration in 3 days is about 230Jg, but for medium-heat and low-heat cement, it is lower than 230Jg, and even less than 200J days of conventional cement The heat of hydration is more than 300Jg.

For ordinary cement, the hydration heat of 3 days is about 230 J g, but for medium heat and low heat cement, it is lower than 230 J g, and the hydration heat of Changbi trillion cement is more than 300 J g for 200 J days.

Medium and low heat should be lower than this. In addition, the calorific value of hydration is calculated based on the ratio of the heat of hydration of each mineral in the clinker mineral.

The so-called heat of hydration is the virtual heat released after the combination of water, and this thermal effect is not only caused by hydration, but also sometimes because of a chemical reaction with other media, resulting in a phenomenon. And this phenomenon will bring advantages to the concrete used in winter construction, because it can increase its strength enough.

When the heat of hydration is large and concentrated discharged, for large-volume concrete, the internal temperature of the concrete will rise more due to the accumulation of heat, while the surface temperature is less affected by the environment, and the thermal stress caused by the temperature difference between the inside and outside will lead to the cracking of the concrete. In concrete constructed in the summer, thermal expansion occurs, and cracks occur when cooled. The advantages of hydration heat: when the hydration heat is large, it is beneficial to the concrete of winter construction, and under the insulation measures, the concrete is kept at a certain temperature, so that the frost heave will not be damaged, and the hydration and hardening of cement can be accelerated.

In addition, due to the high internal temperature, it can also promote the early hydration of concrete mixed with mineral admixtures and improve the early strength. For some of the above situations, the influence of heat of hydration should be considered when selecting cement for the preparation of concrete. Additional Information:

The heat emitted by the interaction of cement and water is called the heat of hydration and is expressed in joules (j g). Generally speaking, the hydration process of cement can be divided into three stages from the perspective of heat evolution rate: the first stage can be called the dormnant period, at the initial moment, the cement particles and water contact and react, the exothermic rate is very fast, but due to the presence of gypsum, a layer of passivation mold will be formed on the surface of the cement particles, so that the exothermic rate is reduced, and the second stage can be called the phase-boundary reaction stage, The third stage can be called the diffusion control stage, the thickness of the cement hydration products accumulated on the surface of the cement particles gradually thickens, the hydration heat release rate of cement gradually decreases, and the reaction at this time is controlled by diffusion.

How to evaluate the pros and cons of cement hydration heat? 1. The heat of hydration refers to the heat released by the interaction between cement and water, which is expressed in joules (know j g). 2. Hydration heat For general buildings and small-volume projects, the hydration heat of the cement can be ignored, and the hydration and hardening of cement can even be accelerated!

However, for large-volume projects, such as dams, bridges, etc., the heat of hydration cannot be released in time, and the accumulation will cause devastating consequences such as capacity expansion and cracking. How to reduce the heat of cement hydration? 1. Increase the amount of fly ash, thereby reducing the amount of cement, 2. Reduce the amount of water, thereby reducing the amount of cementitious materials.

3. Add mineral powder to further reduce the amount of cement. 4. Use low-heat cement (3D, 7D cement with low hydration heat). 5. Reduce the temperature of concrete (less than 25 degrees or lower).

Summary. Hello, there are "medium and low heat Portland cement", slag cement, fly ash cement, composite cement, etc., which need to be determined by hydration heat test.

Generally, in order to reduce the heat of hydration of concrete, we will make a fuss about the ratio, add more fly ash, and extend the acceptance age such as 60d.

What are the cements with low heat of hydration.

This question is up to me, it takes a little time to type, so please be patient.

Hello, there are "good medium and low heat Portland cement", slag cement, fly ash cement bending, composite cement, etc., which need to be determined by hydration heat test. Generally, if the concrete wants to reduce the number of hydration heat burial traces, it will make a fuss from the ratio, add more fly ash, and extend the acceptance age such as 60d.

The heat of hydration is greatest in ordinary Portland cement. Ordinary Portland cement is a hydraulic cementitious material made of Portland cement clinker, 5%-20% mixed material and an appropriate amount of gypsum grinding. It has the characteristics of high strength, high heat of hydration, good frost resistance, dry shrinkage, good wear resistance, good carbonization resistance, poor corrosion resistance, and no high temperature resistance.

In Portland cement, the content of tricalcium aluminate (C3A) in cement contributes the most to the heat of hydration.

Nonsense, Portland cement has the largest heat of hydration.

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Hello dear! We will be happy to answer your answer: the use of fast-hardening (R-type) cement or Portland cement with a high content of tricalcium silicate (C3S) and tricalcium aluminate (C3A) has a high calorific value and a fast exothermic rate.

Inorganic salts that can promote coagulation and improve the early strength of cement can accelerate the hydration rate of cement, and at the same time accelerate the hydration and exothermic rate, such as sodium sulfate, sodium nitrite, calcium nitrite, aluminum sulfate, chloride salt, etc. It must be noted that chloride salts should not be used in reinforced concrete, as chlorine can cause rust in steel bars; The amount of sodium and potassium salt should not be large, otherwise it may lead to alkali-aggregate reaction expansion; Calcium oxide (quicklime) should not be used, otherwise it may lead to poor cement stability.

What materials can improve the heat of hydration of cement accelerates.

Hello dear! We will be happy to answer your answer: the use of fast-hardening (R-type) cement or Portland cement with a high content of tricalcium silicate (C3S) and tricalcium aluminate (C3A) has a high calorific value and a fast exothermic rate.

Inorganic salts that can promote coagulation and improve the early strength of cement can accelerate the hydration rate of cement, and at the same time accelerate the rate of heat release of water, such as sodium sulfate, sodium nitrite, calcium nitrite, aluminum sulfate, chloride salt, etc. It must be noted that chloride salts should not be used in reinforced concrete, as chlorine can cause rust in steel bars; The amount of sodium and potassium salt should not be large, otherwise it can lead to alkali-aggregate reaction expansion; Calcium oxide (quicklime) should not be used, otherwise it may lead to poor cement stability.

These materials are mediocre, and there are no better materials.

Normally, this material is used.

The alkalinity will be worse, but it will reduce the strength of the cement.

Hello, I am glad to answer for you: high hard water in cement slurry can speed up the heat of cement hydration, can promote coagulation, improve the early strength of the cement can speed up the hydration of cement, and at the same time speed up the hydration and heat release rate, such as sodium sulfate, sodium nitrite, calcium nitrite cracking mold, aluminum sulfate, chloride salt, and so on. It must be noted that:

Chloride salts should not be used in reinforced concrete, as chlorine can cause corrosion of steel bars; The amount of sodium and potassium salt should not be large, otherwise it may lead to alkali-aggregate reaction expansion; Calcium oxide (quicklime) should not be used, otherwise it may lead to poor cement stability.

Dear, I am glad to answer for you: the difference between high-heat cement and low-heat cement A: The difference between high-heat cement and low-heat cement is as follows:

There is a difference between high-heat cement and low-heat cement, and the biggest difference is that low-heat cement will turn into liquid at 1700 degrees. The concept of simple and high-heat cement, as the name suggests, is cement that can withstand high temperatures. It has a lot of variety:

High alumina cement, aluminate salt series high-temperature resistant cement, N-type ultra-early strength aluminate cement, pure calcium aluminate cement, phosphate series high-temperature resistant cementitious materials. Of course, the production process of high-temperature resistant cement is also relatively complex.