Name: cement hydration heat and strength gain
Uploaded: 2024-09-12T16:16:35.000Z
Duration: 1 min 29 s
Channel: JoVE

La réaction du ciment avec l’eau pour produire des produits d’hydratation libère de la chaleur, connue sous le nom de chaleur d’hydratation.
Initialement, la génération de chaleur est rapide en raison de l’hydratation des aluminates et des silicates dans le ciment. Une chute soudaine s’ensuit lorsque les produits d’hydratation enrobent les silicates, puis une augmentation progressive à mesure que les silicates restants réagissent après la dissolution du revêtement, suivie d’une diminution et d’une stabilisation éventuelle à mesure que l’hydratation ralentit.
Les composés du ciment contribuent à sa chaleur d’hydratation ; C3A contribue le plus, et C2S contribue le moins.
Pour le ciment Portland, environ cinquante pour cent de la chaleur totale est libérée entre un et trois jours, environ soixante-quinze pour cent en sept jours et près de quatre-vingt-dix pour cent en six mois.
Le C-S-H formé lors de l’hydratation des silicates dans le ciment contribue à sa résistance.
Compte tenu de la variation de la résistance du ciment hydraté avec le temps, l’hydratation de C3S contribue davantage au développement de la force au cours des quatre premières semaines, tandis que l’hydratation de C2S contribue à la force acquise par la suite.
Cependant, au bout d’un an environ, l’hydratation du C3S et du C2S contribue également au gain de force.
En revanche, l’hydratation de C3A et C4AF contribue peu à la force.

Aucun conflit d’intérêts n’a été déclaré.

résistance et chaleur d'hydratation

Strength and Heat of Hydration

L'hydratation du ciment est une réaction exothermique dans laquelle de la chaleur est générée lors de l'hydratation du ciment. Cette chaleur d'hydratation est essentielle au développement de la résistance du ciment. La vitesse à laquelle cette chaleur est générée affecte l'augmentation de la température, la majorité de la chaleur étant libérée au début du processus d'hydratation, la moitié au cours des trois premiers jours et environ 75 % au cours de la première semaine.

La chaleur d'hydratation de chaque composé de ciment est importante ; par exemple, l'aluminate tricalcique (C_3A) et le silicate tricalcique (C_3S) contribuent le plus à ce processus. Le tableau 1 résume la chaleur d'hydratation des composés de ciment tels que C_3S, C_2S, C_2A et C_4A. L'ajustement des proportions de ces composés peut gérer la vitesse et la quantité totale de chaleur libérée pendant l'hydratation du ciment.

Tableau 1. Chaleur d'hydratation des composés de ciment

<div style="text-align: center; display: flex; align-items: center; justify-content: center;">
<table style="text-align: center;" border="1">
 <tbody>
 <tr>
 <td>Composé</td>
 <td>Chaleur d'hydratation (J/kg)</td>
 </tr>
 <tr>
 <td>C_3A</td>
 <td>867</td>
 </tr>
 <tr>
 <td>C_3S</td>
 <td>502</td>
 </tr>
 <tr>
 <td>C_4AF</td>
 <td>419</td>
 </tr>
 <tr>
 <td>C_2S</td>
 <td>260</td>
 </tr>
 </tbody>
</table>
</div>

Le développement de la résistance du ciment hydraté est principalement influencé par les composés silicate tricalcique (C_3S) et silicate dicalcique (C_3S). Le C_3S contribue de manière significative à la résistance au cours des quatre premières semaines après l'hydratation, tandis que le C_2S joue un rôle plus crucial dans les gains de résistance à long terme, en particulier après la première année. Après un an, les deux composés, lorsqu'ils sont considérés sur une base masse pour masse, contribuent de manière égale à la résistance globale du ciment.

Résistance et chaleur d'hydratation

La réaction du ciment avec l’eau pour produire des produits d’hydratation libère de la chaleur, connue sous le nom de chaleur d’hydratation.
Initialement, la génération de chaleur est rapide en raison de ...

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cement hydration heat and strength gain

Cement hydration produces heat and builds strength at the same time. Hydration is an exothermic reaction, which means it releases heat as cement reacts with water. That heat of hydration is a key part of how cement develops strength.

Most of the heat is released early in the process. About half is given off in the first three days, and about 75% is released in the first week. The rate of heat release also affects how much the temperature rises during hydration.

Some cement compounds contribute more heat than others. Tricalcium aluminate, or C3A, and tricalcium silicate, or C3S, are the main contributors. Table 1 shows the heat of hydration for C3A, C3S, C4AF, and C2S. Their values are 867 J/kg, 502 J/kg, 419 J/kg, and 260 J/kg, respectively. By changing the amounts of these compounds, it is possible to control both the rate and the total heat released.

Strength development depends mostly on tricalcium silicate, C3S, and dicalcium silicate, C2S. C3S is important for early strength during the first four weeks after hydration. C2S becomes more important for long-term strength gain, especially after the first year. After one year, both compounds contribute equally to cement strength on a mass-for-mass basis.

Cement Hydration Heat and Strength Gain

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strength and heat of hydration

Cement hydration produces heat and builds strength at the same time. Hydration is an exothermic reaction, which means it releases heat as cement reacts with water. That heat of hydration is a key part of how cement develops strength. Most of the heat is released early in the process. About half is given off in the first three days, and about 75% is released in the first week. The rate of heat release also affects how much the temperature rises during hydration. Some cement compounds...

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Learn how cement hydration releases heat, raises temperature, and drives strength gain. See how C3A, C3S, and C2S affect early and long-term strength.

Cement Hydration Heat and Strength Gain | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

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Cement Hydration Heat and Strength Gain

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