Cold weather concreting is a critical construction activity that requires excellent planning and preparation. This is because even the slightest mistake can affect concrete elements’ strength, durability, and serviceability. Therefore, it is crucial to understand the common mistakes made in cold weather concreting and the suitable measures for avoiding them.
Pouring concrete on the frozen or ice-laden ground, lack of proper covering material and external source, improper scheduling of concreting works, etc., are examples of possible errors in cold weather concreting. Having the right tool at the project site, like thermal blankets and an external heat source, can help avoid undesired delays and unsafe concrete development.
Common Mistakes in Cold Weather Concreting: How to Avoid Them?
1. Pouring Concrete on Frozen Ground
Pouring concrete on frozen ground is a common mistake that contractors should be aware of. This is because a frozen ground provides a hard surface that settles soon after it thaws. As a result, concrete will suffer from cracking.
Moreover, the hydration process of concrete close to the frozen ground will be slower than the top of the concrete member. This means the top of the concrete member hardens while the bottom part is still soft. Consequently, the temperature gradient will occur and crack development will be inevitable.
2. Letting Concrete Freeze
The freezing of freshly poured concrete can reduce its strength by half. In addition, errors at a construction site or unexpected drop in temperature may lead to concrete freezing.Â
Keeping concrete temperature above 10 degrees celsius ensures proper curing of concrete and prevents freezing. Thermal blankets or external sources of heat can be used to maintain the curing temperature of concrete.
3. Utilization of Cold Tools
If construction equipment, embedments, and formwork are too cold, they reduce the temperature of fresh concrete that comes in contact with them. This will slow down the strength development of concrete.Â
Therefore, keeping the temperature of formworks, equipment, and embedments at a minimum of zero degrees celsius is as crucial as maintaining ground and concrete at a suitable temperature.
4. Not Using Heater or Using Heater Improperly
If the ambient temperature is too cold, it can decline concrete temperature significantly. On the other hand, such low temperatures can hold the curing process of concrete. In this case, it is vital to use a heater to maintain the curing temperature of concrete.Â
Contractors should use heaters carefully; otherwise, improper heating can lead to concrete strength reduction. For instance, when a fuel-fired heater is used and proper ventilation is not provided, carbonation makes the concrete surface dusty and weak.
5. Misjudging Daylight
In cold seasons, daylight hours decrease, and hence it is important to use time wisely and schedule concreting during the day. For example, if a contractor runs behind schedule, he could quickly lose out on the daylight required to finish concrete placement.Â
Daylight provides enough light and warmer temperature, which facilitate concrete placement. However, if a contractor is forced to place concrete at night, they need to arrange adequate lighting equipment and a proper heating source. Â
6. Not Using Real-time Temperature Measurement Tools
Monitoring temperature in cold weather conditions is significant for successful concreting. In addition, it helps to keep the curing temperature of concrete and ensure proper concrete strength development.
However, if real-time temperature sensors are not used, there will be errors in concrete temperature monitoring. This may lead to concrete freezing at an early age, improper strength development, rapid temperature changes, improper curing procedure, and insufficient concrete structure protection.
7. Sealing Concrete When its too Cold
Sealing concrete offers several advantages, like improving resistance to harmful substances. However, it should not be done unless the concrete temperature is above 10 degrees celsius. Additionally, sealer used in cold weather conditions should be compatible with extreme weather conditions.Â
FAQs
1. Pouring Concrete on Frozen Ground
2. Permitting Concrete to Freeze
3. Utilization of Cold Tools
4. Not Using Heater or Using Heater Improperly
5. Misjudging Daylight
6. Not Using Real-time Temperature Measurement Tools
7. Sealing Concrete When Its too Cold
Cold weather concreting mistakes can detrimentally affect the strength, durability, and serviceability of concrete elements.
Keeping concrete temperature above 10 degrees celsius ensures proper curing of concrete and prevents freezing.
Pouring of concrete on frozen ground is a common mistake that contractors should be aware of. This is because a frozen ground provides a hard surface that settles soon after it thaws. As a result, concrete will suffer from cracking.
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