There is a great need for accelerated binders in concrete technology. It must thereby be decided whether the setting or the curing of the concrete should be accelerated. Proven systems are available for achieving fast setting. For example, the start of the setting process in spray concrete is shortened to an order of minutes by the use of spray concrete accelerators with alkalis (alkali silicate and aluminate) or without alkalis (aluminium sulphate and hydroxide). Until now there have been few options available for accelerating curing whilst maintaining an adequate processing time. The conventional measures offered by concrete technology for increasing early strength, such as higher cement content, low water-cement ratio and the use of cements of a high strength class do not lead to a satisfactory result in every case. The use of accelerating additives is also only possible to a limited extent, since many of these agents can lead to problems with corrosion of the reinforcing steel and are therefore not permitted for use in steel reinforced or prestressed concrete. Due to the lack of alternatives, heat treatment is often used to increase the early strength of precast concrete elements. The heat treatment is being increasingly called into question, in particular on account of rising energy prices, but also as a result of qualitative problems.
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