Eine fachgerechte Nachbehandlung von Beton ist von wesentlicher Bedeutung, um die gewünschten bzw. geplanten Eigenschaften des Betons im oberflächennahen Bereich zu erreichen. Junger Beton muss gemäß DIN EN 13670/DIN 1045-3 direkt nach dem Verdichten bzw. Nachverdichten und dem Abschluss der Oberflächenbearbeitung innerhalb der ersten Tage nachbehandelt werden. Durch die unmittelbare Nachbehandlung soll nicht nur eine ausreichende mechanische Festigkeit und eine hohe Dauerhaftigkeit (Dichtheit) der Betonrandzone sichergestellt, sondern auch das Frühschwinden geringgehalten werden. Basierend auf dem DBV-Merkblatt „Nachbehandlung von Beton“ vermittelt der Beitrag wichtige Informationen zur Auswahl und Durchführung geeigneter Nachbehandlungsmaßnahmen in der Baupraxis.
Curing of concrete – Not only important in summer!
According to DIN EN 13670/DIN 1045-3, young concrete must be cured directly after compaction or post-compaction and the comple¬tion of surface treatment within the first few days. The immediate curing is not only to ensure sufficient mechanical strength and a high durability (impermeability) of the concrete edge zone, but also to keep early shrinkage low. Under certain circumstances, a so-called intermediate curing must be carried out before the actual curing, e.g. for surfaces to be smoothed, in order to minimise possible early shrinkage. The curing and protection of the concrete must be carried out as far as possible without interruption until the concrete has har¬dened sufficiently. This means that curing usually has a disruptive effect on the construction process. It is therefore the general aim of the construction site to keep the curing time as short as possible, but nevertheless to carry it out in accordance with the regulations. Basically, a distinction must be made between (actual) concrete curing and intermediate curing, or intermediate curing may be a necessary part of curing. In addition to the two above-mentioned (standardised) objectives of curing, there may be further technical objectives in both building construction and civil engineering in connection with the requirements placed on the concrete structure. A distinction must be made between curing time and stripping time. If the stripping period, e.g. for concrete walls or columns, is shorter than the required curing period, curing must be continued in a suitable manner after stripping. In addition to the actual curing and, if neces¬sary, intermediate curing, the young concrete must also be protected according to DIN EN 13670/DIN 1045-3 against: harmful weather conditions, such as rain, wind, frost or extreme temperatures as well as temperature fluctuations, harmful vibrations, impacts or damage and, if necessary, damaging contact with substances that attack the concrete (e.g. chlorides in combination with frost or acids). Based on the DBV leaflet ”Curing of concrete“, the article provides important information on the selection and implementation of suitable curing measures in construction practice.