Concrete Care
The hardening of concrete is a complex physical and chemical process accompanied by the formation of new structures under appropriate temperature and humidity conditions.
Concrete care ensures optimal temperature and humidity in the course of hardening. The main factors of structure formation are temperature above zero (preferably not lower than +15 °С) and high humidity (not lower than 90%). In addition, it is crucial to maintain the required temperature and humidity in the placed concrete, preventing it from overdrying and freezing. Depending on the weather conditions, concrete is also protected from the wind.
Care of concrete begins immediately after pouring it and smoothing the surface. However, depending on the type of the structure, particular care recommendations are most efficient under certain conditions.
| ACTION | MATERIAL |
| Cover the concrete surface with a film to form an enclosure |
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Concrete is usually cared for until it reaches 80% of the design strength.
Freshly placed concrete must be protected from stress, shaking, and other physical damage.Care of concrete in the summer
In the summer, the process of water evaporation is more intense due to rising air temperatures; therefore, the process of concrete care envisages protection against premature overdrying:
- At temperatures above +25 °C, carry out concreting after sunset or early in the morning, before sunrise.
- Start watering the concrete 5-10 hours after placing
- At air temperatures above +15 °C, water the concrete every 3 hours. The time interval between watering can be decreased if the ambient temperature is high or increased if the air temperature is below +15 °C.
- Cover the structures with sheets (strips) of polyethene film.
Care of concrete in the winter
Every effort to take care of concrete in the winter must prevent the concrete from freezing. At temperatures below +5 °C, special attention should be paid to care of concrete because at this time, the hydration of cement in concrete — and, consequently, structure formation — slows down. At an ambient temperature of about 0 °C, the slowed hydration reaction in concrete leads to a decrease in the temperature, and the released heat may not be enough to maintain it in the positive range. At a critical temperature of 0 °C, the water in the concrete begins to crystallise into ice, its volume expands, and the concrete collapses.
- Use special electrical devices to heat concrete structures and add antifreeze agents.
- It is necessary to thermally insulate the formwork and the top part of the concrete structure with any heat-insulating material. Its main task is to preserve the heat obtained from the hydration of cement.
Read more about concreting in winter here.