For the manufacture of precast concrete elements, one of the important and determining components to obtain high-quality elements that meet the requested requirements depending on the type of mixture that is had is the additive.
Dry mixes: The main characteristic of dry mixes is not to have a settlement, and the elaboration of the prefabricated pieces is by vibrating and compaction in the vast majority of cases. They generally have a high proportion of fine aggregate, between 70% and 100% of the total volume of aggregates used (due to the chemical company Malaysia manufacturing technique of the elements already mentioned).
As soon as the characteristic or property required in the precast element is identified or determined, the chemical additive must be chosen focused on solving the possible difficulties that may arise when producing it with dry mixtures, and in the case of dry mixtures, the most used additives depending on the use they are:
Plasticizing additives: composed of polymers with high dispersion power that provide appropriate consistency to dry concrete mixtures.
Its uses: for concretes with a poor gradation of aggregates that generate porous and poorly cohesive mixtures. Also for high-performance concretes.
Lubricating additives and texture enhancers: these facilitate the placement of concrete because they allow adequate lubrication of the materials in the processes of vibration and compaction of the pieces.
They also provide prefabricated pieces with medium to high textures, improving the aesthetics of the products.
Efflorescence Control Additives and Absorption Reducers – These additives feature multi-functional technology using silicone polymers and components that resist moisture migration.
Likewise, they perform an internal blockage in the concrete, which reduces the absorption of the elements and the transport of salts inside it, thus reducing the phenomenon of efflorescence.
Additives for the integral color of concrete: these products create aesthetic and differentiating pieces. They are specialized inorganic synthetic pigments to preserve color stability over time.
Wet mixes: This other type of mix has settling, which, in most cases, exceeds 5 ”(12.7cm) and/or is also found in extensibility applications. The main requirement for these mixtures is associated with the production of concrete with high initial strength at ages of 14 and 24 hours.
In the case of this mixture, there are additives such as:
Super plasticizing additives composed of polymers with high dispersion power: they provide appropriate rheology to precast concrete, both in slump and extensibility mixtures.
These additives are used for the configuration of concrete with a low water/cement ratio, concretes with aggregates that generate rough and not very cohesive mixtures and high-performance concretes.
Additives to control the hydration of the cement: these facilitate the placement of concrete, have superior workability support with a minimum impact on setting times.
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