What are air bubble types in concrete

Baunetz_Knowledge

Concrete admixtures
Concrete admixtures are substances that are finely divided into concrete (liquid, powder, in certain cases also as granules or paste) in small amounts in order to influence certain properties of the fresh concrete or the hardened concrete through chemical or physical effects. With a maximum allowable amount of 50 g or 50 ml per kg of cement for concrete and reinforced concrete or 20 g or 20 ml per kg of cement for prestressed concrete, they are irrelevant in terms of material volume.

Concrete admixtures must be uniform. They are to be described visually, namely liquid concrete admixtures according to color and consistency and powdery concrete admixtures according to color and grain structure. A further parameter is the density of liquid concrete admixtures and the bulk density of powdery concrete admixtures.

Concrete admixtures must be compatible with concrete and must not impair the corrosion protection of the reinforcement. For this reason, certain chemical compounds as active ingredients (e.g. halogens, nitrites, nitrates) must not be added. Effect groups of concrete admixtures:

  • Concrete liquefier (BV)
  • Superplasticizer (FM)
  • Air entrainer (LP)
  • Sealant (DM)
  • Retarder (VZ)
  • Accelerator (BE)
  • Press-in aids (EH)
  • Stabilizer (ST)

Concrete additives
Concrete additives are finely divided substances that are used in concrete to improve or achieve certain properties. DIN EN 206-1 Concrete - Part 1: Specification, properties, production and conformity / DIN 1045-2 Structures made of concrete, reinforced concrete and prestressed concrete - Part 2: Concrete - Specification, properties, production and conformity distinguish between two types of inorganic additives:

  • Type I: almost inactive additives such as rock flour according to DIN EN 12620 aggregates for concrete or pigments according to DIN EN 12878 Pigments for coloring cement- and / or lime-bound building materials - requirements and test methods or with general building authority approval
  • Type II: pozzolanic or latent hydraulic additives such as Trass nach DIN 51043 Trass; Requirements, testing; Fly ash after DIN EN 450 fly ash for concrete - Part 1: Definition, requirements and conformity criterian or silica dust with general building authority approval

Concrete additives (also called fillers) are to be considered as volume components, as these are added to the concrete in significantly larger quantities than the concrete additives.

Expertise on the subject

properties

Influence of additives

Concrete admixtures are liquid or powdery substances that are added to the concrete. This is intended to reduce the chemical and ...

properties

Influence of additives

Concrete additives are finely ground additives such as hard coal fly ash, color pigments, silicate dust, glass, fibers. By the...

Manufacturing

Composition of concrete

Cement, water and aggregates are the raw materials for the building material. It can be adapted to the respective requirements by means of additives and substances.

BauNetz Wissen Beton sponsored by:
German cement and concrete industry represented by the
Information center concrete | Contact 0211 / 28048–1 | www.beton.org