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Concrete Pro Tips for St Charles, Lincoln and Warren Counties
At Schreiter Ready Mix & Materials, you'll find concrete experts handling your orders. It takes a wealth of knowledge and experience to mix concrete to the specifications of a wide range of projects and even more to guarantee quality. At Schreiter, we can make that guarantee. We have the knowledge needed to be experts in concrete. We will also share some great tips about our products on the house. Just give us a call.
Hot weather placement
Problems generally associated with the hot weather in summer can happen any time of year. High winds, low relative humidity, and solar radiation can produce rapid evaporation of moisture at the surface of the concrete.
Concrete placed at high temperatures will set quicker and will need more rapid finishing. A high evaporation rate at the surface may cause plastic shrinkage and dry shrinkage. Crusting the surface while the underlying concrete is still movable is a sign that evaporation is occuring.
Precautions such as the use of windbreaks, cooling with ice in concrete and evaporation retarders should be considered to reduce error when concreting in higher temperatures. Other considerations include having adequate manpower to finish and cure, and using a white pigment curing compound or another method to hold in moisture after setting. Remember to dampen the sub-grade before placing concrete.
Cold weather placement
The rate of cement hydration is highly dependent on the concrete temperature. We provide heated mix water in colder weather to decrease the concrete setting time and increase the overall rate of strength gain.
Accelerators such as calcium chloride and non-chloride accelerators are available and are used to speed the setting time for certain job conditions and specifications. Calcium chloride can darken the color of the concrete and may react with steel reinforcement. If these are a factor, non-chloride is the product to use.
Concrete exposed to cycles of freezing and thawing and in contact with water should be air-entrained. Slabs of fresh concrete should be protected from freezing until it attains at least 3,500 psi compressive strength and should never be placed on frosted or frozen sub-grade. Insulated blankets or straw and poly-film are used to retain heat during curing.
Curing
Curing means keeping the water in concrete where it can do its job. Improper curing can cut the strength of concrete by 50%. Keeping the water in allows it to combine with the cement to form a tough glue, which means the concrete shrinks less, cracks less, dusts less, and is stronger and more durable.
Curing must start as soon as concrete hardens. Membrane curing compounds are the most practical and widely used. They can be sprayed or rolled on to hold water in.
Water sprayers are sometimes used but must be continuous. Recommended practices call for a minimum of seven (7) days duration of curing or until 70% specified compressed strength is attained.