https://graestone.com/wp-admin/admin.php?page=wpcf7 Technical Information - Graestone Ready Mix

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Technical Information

Cold Weather Concrete Curing.

You need to take special precautions when placing concrete during cold weather. If you don’t, your concrete might not be as strong or as durable. The risk is greatest when temperatures go below five degrees Celsius during or within 24 hours of placing.

To prevent cold weather concrete problems:
• Use special winter mixes.
• Do not pour concrete on frozen ground or rebar.
• Cover the ground or forms and use heaters to warm the area up.

Hot Weather Concrete Curing

Hot weather conditions can be just as detrimental to concrete as cold weather. Hot weather makes concrete harder to work with and it can also lead to shrinking and cracking.

To prevent problems resulting from hot weather, it is important to use windbreaks, sunshades, and wet coverings as needed. In some cases, we may also use water to keep the placement area damp. There are also special admixtures and surface applications we can use to reduce shrinking and cracking.

At Graestone Ready Mix, we are experts in placing and curing concrete in all kinds of weather conditions. Contact our knowledgeable staff to learn more about how we can help you.

Concrete Cracking

  • Usually, the result of improper jointing.
  • Improper subgrade preparation.
  • The use of high slump concrete or excessive addition of water on the job
  • Improper finishing techniques
  • Inadequate or no curing

To prevent cracking

  • Use proper joint spacing
  • Consistent compacted subgrade topped with 20mm clear rock to allow for proper drainage
  • Pour at a maximum 100mm slump or 125mm slump with super plasticizer
  • Use proper CSA finishing techniques
  • Use proper curing techniques such as liquid curing membrane or cover with wet burlap
  • Follow guidelines for cold or hot weather concreting
  • Concrete cracks so you want to do your best to control it

Concrete Scaling

  • Scaling is local flaking or pealing of a finished surface of hardened concrete because of exposure to freezing and thawing. Generally, it starts as small, localized patches which usually merge and extend to larger exposed patches.
  • Light scaling does not expose the aggregate
  • Moderate scaling exposes the aggregate and may involve losing up to 3mm to 9.5mm of surface mortar.
  • Severe scaling, most of the surface is lost and the aggregate stands out.

To prevent scaling

  • Concrete exposed to freeze/thaw cycles must be air-entrained with 5%-8% air and as per CSA a minimum of 32 mpa with a water/cementitious ratio of .45 or less, poured at a maximum of a 100mm slump or up to 125mm slump with the addition of super plasticizers.
  • A steel trowel finish should never be used on air entrained concrete.
  • De-icers of any kind should not be used in the first year. Use clean sand for traction. Concrete should be cured and after curing it should be allowed to dry out for 30 days.
  • Provide proper curing by using a liquid membrane curing compound or cover with wet burlap. Curing ensures that proper hydration takes place to ensure concrete reaches it highest potential strength.
  • Do not overwork the surface while finishing as it will reduce the air content and make the concrete more susceptible to scaling in freeze thaw conditions.

Material Safety Data Sheets (MSDS)

Looking for safety information on our products? Contact us for MSDS sheets for any of our products.

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