Quality control of concreting in cold temperature
- Shielding of wind in the working area and insulating the plant with insulators.
- The site shall be well managed for quick delivery, finishing and covering of the concrete with insulator like straw, jute sacks, plastic sheets, water-proof paper, etc.
- The material for concrete can be pre-heated. Water can be easily heated in a container. Coarse aggregate can be heated with closed steam coils under stock pile, or by steam or hot air, if stored in a room. Sand can be heated over steel plates, while cement shall not be heated.
- The form-work or sub-grade can also be heated (to the temperature of concrete) so that heat of concrete is not absorbed by them.
- Special type of cement like rapid hardening cement, high alumina cement, etc. can be used that have higher heat of hydration and keeps the concrete warm.
- Accelerating admixtures is also commonly used that increases the rate of hydration. Calcium chloride is a good accelerator, but use in higher amount increases the corrosion in steels embedded in RCC.
- Where possible, electrical heating can also be adopted for curing (maintaining the temperature) of the concrete by passing alternating current through it.
- Where caging is possible, especially in pre-cast industry, low pressure steam (or hot air) circulation maintains the temperature thus accelerating the hydration