Concrete is one of the most frequently used building materials of our time. Due to growing demands, this three-substance system (aggregates, water, cement) that has been known for centuries has become a system that fulfils modern construction demands due to the use of concrete admixtures and additives. The use of concrete admixtures in a powder and/or fluid form has a lasting effect on the fresh and hardened concrete properties depending to the type of admixture. When using one or several admixture types, the installer needs to verify the effectiveness in an initial test patch.
Concrete admixtures of the plasticiser type (FM) has a plasticising effect on the fresh concrete. The working time of this admixture is about 30 minutes and is temperature dependant. By using a plasticiser, the water content can be reduced and the consistency is retained, or the water content can be retained and the workability can be increased.
Concrete admixtures of the delaying agent type prolong the time between mixing and the transition of the fresh concrete to new concrete. The associated longer workability time of the fresh concrete is necessary to ensure compliant installation and compression at high temperatures. In the case of large building structures, the use of these agents ensures that the individual concrete layers are correctly compressed.
Concrete admixtures of the water-proofing type reduce the capillary water uptake and can give the concrete water repelling (hydrophobic) properties. The requirements of the DIN EN 206-1 / DIN 1045-2 and the DAfStb guide lines also need to be observed for concrete with a high water penetration resistance.