Quikrete Fast-Setting Concrete Mix 50 lb Bag, Sets in 20 to 40 Minutes

What It Is For

This is a general purpose concrete formulated to set fast. Quikrete rates it for setting posts, sleeves and anchors, and for pouring slabs at two inches or thicker. The appeal is the return to service: four hours before the post takes any strain, rather than the day you would wait with a standard mix.

• Final set in 20 to 40 minutes tested to ASTM C191.
• 1000 psi at 24 hours, 2500 psi at 7 days, 4000 psi at 28 days, tested to ASTM C39.
• Can be dry poured for posts. Pour the dry mix into the hole and add water, roughly one gallon per 50 lb bag depending on soil.
• Or mixed conventionally, about 4 pints of water per 50 lb bag, up to a maximum below 5 pints.
• Meets or exceeds ASTM C387 compressive strength requirements.

Specifications

Coverage for Setting Posts

Two 50 lb bags will set a 3 inch square post in a 9 inch diameter hole 30 inches deep. Allow at least three quarters of a cubic foot of mixer capacity per 50 lb bag if you are mixing rather than dry pouring.

How to Use It

• Mix only what you can place in 20 minutes. This is the one rule people break, and a wheelbarrow of set concrete is an expensive lesson.
• For slabs, pour at 2 inches or thicker. Cut control joints 1 inch deep every 6 to 8 feet.
• Wait 4 hours before the post takes strain, or before walking on a slab or setting anything heavy on it.
• Cure 5 days in warm weather at 70 F or above, or 7 days in cooler weather.
• Protect from freezing for the first 48 hours. Use plastic sheeting or insulation blankets if it may drop below 32 F.

Things Worth Knowing

• Set times shift with the weather. Use cold or iced water in severe heat, warm water in severe cold.
• Keep de-icers off it for at least 28 days, and Quikrete notes that waiting 56 days or more is better still.
• Do not overwork the surface. It brings water and fines to the top and weakens the finish.
• Wear gloves and eye protection. Wet cement causes severe burns, and the dust is a respiratory hazard.