Sustainable concrete: what you need to know

Strong, cost-effective and ecological, concrete is a select material for many structures. Do you have a project to complete? Read on, because the durability of your concrete depends on how it is made, but more importantly, how it is installed. Proper installation is essential if you want a durable product that will last for decades. 

Atmospheric conditions for concrete placement

Placing concrete in cold weather

Since fresh concrete contains 15 to 18% water, it is vulnerable to freezing. The compressive strength of fresh concrete exposed to cold climates can decrease by up to 50%. Therefore, placement should be avoided at all costs when the temperature is below -18°C. Use of setting accelerator, superplasticizers and air-entraining admixtures is strongly recommended. It is also important to protect concrete from freezing by using insulating blankets, heated shelters, etc.

Concrete Placement in Hot Weather

High temperatures, low relative humidity, gusty weather, and several other factors can cause concrete to set too quickly due to water evaporation in the mix. The result: cracks and reduced compressive strength. To avoid such consequences, certain preventive measures must be applied: protect fresh concrete exposed to sun, wind and weather, moisten surfaces in contact with fresh concrete such as granular foundations, hardened concrete, forms, as well as use retarders and superplasticizers.

Finishing of Concrete Slabs

Handling of the concrete finish is critical and should be performed by an expert to prevent segregation. It is important to avoid sealing surfaces too quickly, especially with a steel trowel. Bleed water must be completely evaporated before finishing. Never use a steel trowel to finish air-entrained concrete, as its use significantly reduces the freeze/thaw resistance of the surface and increases the risk of delamination.

Curing of Concrete

This step of maintaining the temperature and humidity of the concrete at the right level is crucial to achieve the essential properties of a durable product. Concrete must be protected to avoid water loss during the entire finishing period. Curing should begin immediately after the finishing stage and continue for 3 to 7 days. Keep the forms in place as long as possible.

Joints in Concrete Slabs

To prevent cracking of concrete slabs, it is recommended that joints be made at specific locations. Exact location of the joints must be determined before the work begins and they must be made as soon as possible after the final setting of the concrete. The joint groove should be at least a quarter of the thickness of the slab.

Residential-Use Concrete

Slabs of all kinds, patios, stairs, galleries, foundations and walls are just a few examples of how concrete is used in our homes. Several factors influence the quality of concrete in residential construction and it is important to respect various recommendations:

• Properly assess the bearing capacity of soils to adequately size foundations;
• Plan enough concrete and a good delivery rate to avoid cold joints;
• Never pour concrete on a frozen or reworked and uncompacted surface;
• Provide rebar at the perimeter of the openings.

For more information, see our article on the subject.

Do you have questions about our product or would you like to speak to a Bellemare Béton expert? Contact us now!