Method and system for producing a concrete work piece prestressed by reinforcement

A method for manufacturing a prestressed concrete workpiece formed from fresh, quartz sand-based concrete and a steel reinforcement, the method comprising:

• generating the prestress by a thermal treatment
• in which the fresh concrete and reinforcement are heated to an elevated temperature and then cooled, the fresh concrete being selected to comprise a silica dust in such a way that the thermal expansion coefficient of the fresh concrete transitions from higher to smaller than that of the reinforcement during said cooling, and the concrete and reinforcement adhering to each other in the cooling process;
• at least partially hydrating the fresh concrete in the cooling process, the reinforcement expanding owing to different thermal expansion coefficients between the concrete and the reinforcement provided during said cooling;
• and
• elevating the temperature of the fresh concrete and reinforcement for said heating in such a way and hydrating the concrete in the cooling process to an extent that the prestress is formed by the reinforcement after said cooling,
• wherein the thermal expansion coefficient of the fresh concrete becomes smaller as the result of the heating.