Concrete FAQ - Common Questions Answered
Answers to the most frequently asked questions about concrete, mixing, pouring, and curing
How long does concrete take to cure?
Concrete reaches about 70% of its full strength in 7 days and 100% in 28 days. However, you can walk on it after 24-48 hours and drive on it after 7-10 days. Full curing continues for months, but 28 days is considered the standard cure time.
How long until I can drive on new concrete?
Wait at least 7 days before driving on a standard 4-6 inch driveway slab. For heavier vehicles or thinner slabs, wait 10-14 days. Winter pours require longer wait times - up to 30 days in very cold conditions.
Can you pour concrete in the rain?
Light rain won't harm freshly poured concrete, but heavy rain can damage the surface. If rain is forecast, postpone the pour or have covers ready. If caught in rain, cover the concrete with tarps immediately.
How much does a yard of concrete cover?
One cubic yard of concrete covers 27 square feet at 12 inches thick, 54 sq ft at 6 inches thick, 81 sq ft at 4 inches thick, and 108 sq ft at 3 inches thick. This is the most common measurement used when ordering ready-mix concrete.
What happens if it rains after pouring concrete?
Light rain within a few hours of pouring usually won't cause damage. Heavy rain can wash out cement, create surface blemishes, or weaken the surface. If rain occurs before concrete sets, cover it or trowel the surface once rain stops.
Do you need rebar in concrete?
Rebar is not required for all projects but provides structural strength. Driveways, garage floors, and structural slabs should have rebar. Patios and walkways can use wire mesh or fiber mesh instead. Rebar should be placed in the lower third of the slab for maximum effectiveness.
How many 80lb bags of concrete in a yard?
One cubic yard of concrete requires approximately 45 bags of 80lb concrete. Each 80lb bag yields about 0.60 cubic feet. For comparison, it takes about 60 bags of 60lb concrete to equal one cubic yard.
What PSI concrete for a driveway?
Use 4000 PSI concrete for residential driveways. This provides adequate strength for vehicles and resists cracking. 3000 PSI may be sufficient for light vehicles, but 4000 PSI is the recommended minimum for durability.
How thick should a concrete driveway be?
Standard residential driveways should be 4-6 inches thick. 4 inches is sufficient for passenger cars, while 6 inches is recommended for heavier vehicles like SUVs and trucks. The edges should be thickened to 8-12 inches to prevent chipping.
Should I wet concrete while curing?
Yes, keeping concrete moist during curing improves strength. Spray the surface with water 2-3 times per day for the first week, or cover with wet burlap, plastic sheets, or curing compound. Never let concrete dry out completely during the first 7 days.