The process of preventing excessive cracking in concrete starts with proper preparation and implementation of preventive measures. It can be a challenge to keep concrete from cracking, but there are a few steps that can be taken to reduce the chances of excessive cracking in your next project. Here are seven ways to prevent excessive cracking in concrete:
1. Proper Framework
Use properly designed and built forms. Poor formwork can lead to excessive cracking due to uneven loads, improper curing, and/or inadequate bracing. Make sure your form design is appropriate for the size of the concrete pour and that it’s properly built with adequate bracing to prevent movement or shifting during the curing process.
2. Quality Materials
Use good quality, durable concrete materials and properly proportioned mixtures. If the mixture contains too much water or is prone to shrinkage issues, it can lead to excessive cracking. For best results, consult your local concrete supplier for recommendations on their preferred mix design.
3. Temperature Control
Keep temperature fluctuations and extremes to a minimum during curing by monitoring the ambient temperature of your pour area with a thermometer. Insulated forms can also be used to maintain a consistent temperature during curing. There are also curing blankets available that can wrap around the pour area, providing insulation and helping to maintain a consistent temperature.
4. Curing Method
Properly cure the concrete according to industry standards—this includes keeping it moist and free from damage for an appropriate amount of time after pouring. Wet curing is generally recommended, but other methods such as using plastic coverings or polyethylene blankets can be used.
5. Consistent Mixing
Take care to ensure that the concrete is mixed properly and that all ingredients are blended thoroughly for an even consistency throughout the entire pour. This will help to prevent weak spots which could lead to excessive cracking. The best way to accomplish this is by using a concrete mixer, other equipment and tools, and/or by having multiple people mixing the concrete at once.
6. Control Joints
Properly placed control joints can help to reduce cracking. These are intentional weak spots that allow the concrete to move and expand without cracking the entire surface. When designing your project, plan for where these joints should go so as to minimize the chances of excessive cracking. The American Concrete Institute provides guidelines for properly placing and spacing control joints.
Reinforcing steel, such as rebar, can be used in areas where additional strength is needed or where greater flexibility is desired. This will help to reduce the chances of excessive cracking due to heavy loads or temperature fluctuations. If you’re unsure of how much and where to use rebar, consult with your local concrete contractor or supplier.
By following these simple steps, you can help to reduce the chance of excessive cracking in your concrete surfaces. Proper planning and preparation are key to a successful pour and a durable end product. With the right materials, form design, and curing method, you can ensure that your concrete will last for years to come.