Everything about white cement

  Hydration heat, which warms the concrete itself

Cement during the binding process, or hydration (because the process water is involved) releases large amounts of heat. The better, the cleaner cement (ie, the smaller the Roman numeral designation after CEM), the amount is greater. Usually, it is connected with the fact that branded cements with higher strength usually have an R in the name. This letter tells us that the initial increases in strength occur very quickly. Unusual is not the fact that 80 percent or more, they gain strength after 7 days, when the norm gives them time to achieve the desired parameters up to 28 days.

White cements almost by definition, are better, which means that the amount of heat releasing is really high. This has two major consequences:

  • during summer or at a time when it is especially hot this fact forces especially careful to take care of concrete, usually consisting in cooling the poured concrete layer, not to harden too quickly; If the cement is used for mortar or plaster, you may need to control the growth rate of strength, it not turned out that hard too fast
  • second, a much more significant feature is the ability to carry out construction work in the late autumn or even early winter periods , as well as from late winter. In this case, it suffices only to protect the concrete impermeable material, for example. tarpaulin. The rest will make it for us. Just heat, which emits that will make it warmed himself. Warmth make the water contained in the concrete used for the binding process does not freeze

People working on the concrete nodes, which are used cement type R, are often faced with the phenomenon of evaporation of concrete, even during light frosts. This is a powerful couple the heat given up by cement, which begins bound water

These same characteristics are used by crews working outside bricking different fence by surrounding houses with brick or stone. Experienced professionals know very well that small negative temperatures do not harm the process of binding. This is a simple reason - in mortars, they use component is a white or gray cement - the most common grade of 52.5 marked with the letter R.

It would appear that since despite the fact that the heat is emitted, but the concrete itself does not feel warm or even hot, is not it too much. This is only an illusion ...

Throughout, the complete process of hydration plain, pure portland cement emits approx. 400 kJ of energy. Cements strength approx. 60 MPa at a temperature of approx. 5C can within the first 6 hours separated almost 25 kJ. A lot of it or a little?

1 calorie is less than 4.19 J of energy, or 1 kcal is equal to 4.19 kJ respectively. About 80 kcal need to boil 1 liter of water at room temperature. 25 kJ is approx. 6 kcal or the amount of heat which emits 13 kg of cement strength approx. 60 MPa at a temperature of 5C would boil 1 liter of water for 6 hours ...

The amount of energy which releases 100 kg of portland cement of the same grade during these 28 days is approximately similar value as a 1.5 kg of gasoline

As is clearly marked, the enormous amount of heat emitted by cement without additives with high final strength. The cement has a faster initial resistance increases, the quantity of this energy which is separated, is higher. It is this energy that makes spite of adverse conditions can be concrete, bricklaying, perform works, the weather conditions in theory, deny and should prevent them. And you only need a little help just tightly while covering the poured concrete to the rest made itself.

Qubic meter, or 1 m3 of concrete, according to the most traditional assumptions consists of about 400 kg of cement. Amount of heat to be emitted at a temperature of 5C at the above-mentioned assumptions on these zagotowałaby 6 hours at between 30 liters of water or allow the almost month (28 days) to produce an energy of 4 liters of gasoline.

In cool or cold weather can be accelerated by adding to the binding cement mortar or concrete hot or even very hot water, then the beginning of the process and the first hours of bonding will occur much faster than it would result to the low ambient temperature. This in turn will make the amount of heat generated will not allow even negative temperatures caused us problems.

It is assumed that secure the strength of concrete or mortar freezing in a situation where the binding process has not been completed (i.e., the temperature drops below zero, not yet elapsed min. 28 days) for cement without additives (designation CEM I) is 5 MPa.This means that they give off so much heat that after crossing the strength of the concrete itself does not freezes, or for this to happen they must be very large frost. In order to realize, after a short period of time this occurs, it is sufficient to mention that are available on the market of white cement CEM I, which after 24 hours reaches a strength above 20 MPa, taking and that the start of the bonding process after approx. 2 hours. this is quite an electrifying pace.

You have to learn how to use this potential and the possibilities offered by cement high quality, not to be afraid concrete, bricklaying or plaster even on cooler days. The amount of heat emitted during the binding will make there will be problems, you only need to know how much water is used for concrete or mortar and cement which was used and in what amounts. The rest will be somehow "behind our backs".

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