Prediction of Strength and Quality Control of Monolithic Concrete Laying in Structures with Permanent Formwork

When erecting a number of nuclear power plant structures, a precast-monolithic construction technology is used using reinforced formwork blocks consisting of a reinforcing frame and permanent formwork made of steel fiber concrete. The use of this technology allows to reduce the time of construction of the facility. At the same time, a number of problems arise related to the strength assessment and quality control of the laid concrete located behind the permanent formwork. The lack of direct access to the concrete surface does not allow the use of standardized non-destructive strength assessment methods. Defects of mono-lithic concrete in the form of caverns and voids become hidden and the use of specialized instrumental methods is required. To select the optimal method for assessing the strength of concrete and quality control of its laying, experimental studies of a fragment of a reinforced formwork block with laid monolithic concrete were carried out. It was established that the optimal method of quality control of laying is ultrasonic tomography, which allows to detect a defect be-hind permanent SFRC formwork, as well as to control reinforcement parameters. As a result of testing, it was proposed to use methods of predicting concrete strength based on temperature-time dependencies.

armour formwork block, permanent formwork, steel fiber concrete, quality control, strength prediction