INFLUENCE OF PLASTICIZING-ACCELERATING ADDITIVES ON THE KINETICS OF CONCRETE STRENGTH AT ALTERNATING TEMPERATURES

Abstract

The article presents the results of a comprehensive study on the influence of polycarboxylate-based superplasticizers and non-chloride hardening accelerators on the strength development kinetics of concrete under alternating temperature conditions, which are typical for the cold seasons. The difference between these types of additives is depicted: the polycarboxylate ether-based superplasticizer demonstrated a significant water-reducing effect, improving workability and strength by enhancing cement particle dispersion and hydration. However, it slightly delayed the early strength gain. The addition of the hardening accelerator compensated for this effect by promoting rapid hydration of clinker minerals and slightly lowering the freezing point of the mix water. The findings confirm that the combination of polycarboxylate superplasticizers and hardening accelerators is an effective technological solution for enhancing the strength development kinetics of concrete in fluctuating and low-temperature environments. Such an approach promotes faster early strength development, facilitating earlier formwork removal and load application. At the same time, it allows for reduced cement usage and lowers the energy requirements for heating concrete during cold-weather construction. Winter concreting presents significant technological challenges, including the risk of freezing water within the concrete matrix. One of the most critical factors is the prevention of water freezing inside the concrete matrix and ensuring the achievement of a minimum critical strength as early as possible. Therefore, it is necessary to use heated mixing water to maintain the initial temperature of the concrete mix above +5 °C. Proper curing conditions should also be ensured throughout the early hardening period.