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The effect of shallowness, temperature and humidity for the maturation process
The fineness has a very significant influence on the ripening process. The finer the grains, in the same volume of cement, there is a greater area of cement-water contact, and therefore a larger area, on which it takes place …
Heat of cement hydration
The setting of cements is an exothermic process, i.e., that heat is released during setting. The amount of heat released depends very much on the type of cement, but as a rule it is so big, that this phenomenon must be taken into account in many practical cases with …
Components of the internal structure of the hardened grout
When analyzing the internal structure of the ripe grout, it can be taken figuratively, that the cement stone is "micro-concrete” composed of:
• reliktów ziaren cementowych (meeting the aggregate roadstead),
• zhydratyzowanego cementu w postaci żelowokrystalicznej (the role of the binder),
• wody wolnej, because …
Rheological properties of cement slurry
The rheological properties are characterized by liquidity, susceptibility to deformation under the influence of the acting force and maintaining homogeneity at the same time. The listed features are important from the point of view of the concrete mix, the fluidity and stability of which depend on the freedom of movement of the aggregate grains …
Cement storage
Bagged cements should be stored in closed warehouses. They are to be sealed and dry, and in winter, as far as possible, heated. Cement should be stacked in this order, that the oldest cement is always used.
If cement is stored …
Aging of cements
Aging of cements is manifested by a decrease in their strength properties and a delay in the beginning and end of setting. The reason for aging is the hygroscopicity of cements, as a result, they combine with the moisture in the air, partially reacting prematurely. Higher class cements are …
alumina cement
Aluminum cement differs significantly in its structure, chemical composition and setting process from the Portland cements family. The main factor causing the binding here is A2O3 alumina, and not CaO.
Above 70% cement composition are calcium aluminates of various …
Expansive cement
A characteristic feature of the expansion cement is the increase in the volume of the grout during setting and hardening. This phenomenon occurs as a result of the reaction between calcium aluminate and gypsum. Then the tricalcium sulphate aluminate is formed with a volume increased by 130% in relation to the sum of the volumes …
Sulphate-slag cement
As a result of using an increased amount of gypsum and blast furnace slag in the production of sulphate-slag cement, this cement. after hydration. it contains much less calcium hydroxide and is therefore highly resistant to aggressive factors. Its serious disadvantage, however, is its aggressiveness in …
Hydrophobic cement
It is also cement made of Portland clinker, but with a hydrophobic admixture, which is deposited on the surfaces of the cement grains, preventing the sorption of moisture from the air. On the other hand, during the formation of the grout structure, and thus the concrete settles on the walls …