Boundary conditions for the unerring achievement of projected concrete properties in the modern 5-substance system of various concrete constituents

Duration: 01.05.2012 - 31.10.2014

The further development of concrete plasticizing admixtures (especially superplasticizers) has led to the discernible trend of producing more concretes with softer consistencies in recent years. Softer concretes can reduce the amount of energy and physical labor required for placing and compacting concrete, leading to faster work processes and thus ultimately to cost reductions and more economical construction. At the same time, concrete manufacturers are striving to reduce the cement paste content in concrete for economic reasons, as cement accounts for a comparatively high proportion of costs in concrete production. This development is supposedly supported by the use of superplasticizers based on polycarboxylate ethers (PCE). As described in Section 2.1.2.2, the effect of these PCEs is more dependent on external influencing factors compared to conventional superplasticizers based on melamine or naphthalene sulfonate. In line with the above-described trends towards softer concretes with reduced glue contents, it has been increasingly observed in recent years that fish concrete properties change unexpectedly significantly in longer-lasting construction projects despite the same formulation and starting materials. Within the scope of the research project, the most important influencing parameters will be identified which are responsible for the fact that fresh concretes, which are produced over longer periods of time, show unplanned properties such as a changed consistency, signs of sedimentation or an accelerated or slowed down strength development on a case-by-case basis. In addition, criteria for the design of concrete formulations are to be developed which must be fulfilled so that, even under the multitude of influences which can occur during the production of a concrete and its raw materials, no undesirable fresh concrete behavior occurs in the economically optimized 5-substance system and the susceptibility to material- and production-related fluctuations is as low as possible.