Optimization of concrete strength monitoring at intermediate hardening stages

The article addresses monitoring of concrete strength in cast-in-place structures during intermediate hardening stages, specifically the need to establish distinct calibration curves for different age inter-vals. The authors propose shifting the monitoring approach for modern concretes, which exhibit rel-atively high early-age strength (1–5 days), from a calendar-based method to the one based on the degree of maturity, a parameter determined by hardening kinetics of the specific concrete mix and the temperature conditions. The paper examines test cases according to the current standards for non-destructive testing and proposes alternative approaches for adjusting calibration curves with reduced labor requirements. The described method for monitoring concrete strength at intermediate ages enables a 50 % reduction in the testing laboratory's labor costs.