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Among the concrete admixtures, foaming agents are primarily used to produce foamed concrete. These agents can be derived from various substances. Some of these include alkyl sulphates, amine oxides and polygylcol sulphates. These are added to the concrete in the form of liquids or powders.
The most common concrete plasticizers contain naphtha-lene sulphonates and melamine sulphonates. They are usually added in quantities ranging from 0.2 kwa 0.5 % by mass. This is sufficient to increase the slump of the concrete without affecting its water content. Hata hivyo, the amount of these admixtures in a concrete mixture is very low, so they are not allowed to be discharged directly into the sewer system.
These admixtures are not deemed a hazard for humans, as they are biodegradable. They also are non-irritating. The concrete admixtures are classified as safe in accordance with the German Committee on Reinforced Concrete (DAfStb).
The evaluation of the products is governed by REACH, a European legislation that governs the registration, authorisation and assessment of chemicals. The goal is to ensure a high level of protection of human health and the environment.
The majority of concrete admixtures are based on higher condensed compounds. These are mainly composed of salts of higher fatty acids. During the leaching process of these substances, the monomer compounds are essentially removed from the concrete.
A few of the most important representative concrete admixtures are citric acid, lactic acid, malic acid, tartaric acid and gluconic acid. These are generally recognised as safe, though they have some acute toxicity.