When waiting for concrete to dry, keep these timeframes in mind: 24 to 48 hours - after inital set, forms can be removed and people can walk on the surface. 7 days - after partial curing, traffic from vehicles and equipment is okay. 28 days - at this point, the concrete should be fully cured.
Concrete typically takes 24 to 48 hours to dry enough for you to walk or drive on it. However, concrete drying is a continuous and fluid event, and usually reaches its full effective strength after about 28 days.
How long does four to six inches of concrete take to cure? As stated previously, concrete takes approximately 26-30 days to reach its full strength. If the concrete is professionally poured and floated, the curing process should be sound and ensure proper hardening of the concrete base.
Will 32 MPa concrete crack easily? It is not prone to cracking over time because its high compressive strength prevents cracks from forming even if there is uneven pressure on it.
Curing time of concrete is typically 24-48 hours, at which point it's safe for normal foot traffic. After one week, concrete is typically cured enough to handle continued construction including heavy machinery. Concrete is recognized to have reached full strength 28 days after placement.
DO spray new concrete with water. One of the most common methods for curing concrete is to hose it down frequently with water—five to 10 times per day, or as often as you can—for the first seven days. Known as “moist curing,” this allows the moisture in the concrete to evaporate slowly.
20 MPa and 25 MPa
Commonly used for house slabs, driveways, footings and footpaths.
Where a more structural concrete is required you may need to add neat cement to the premixed bag. As a guide, an addition of 1kg to 1.5kg per 20kg bag of Concrete Mix can be used to achieve around 32 MPa concrete (under normal conditions).
It is advised to contact the suppliers listed on this website for more technical information in this specialized area. A higher grade of concrete (> 32 MPa) will also provide watertightness.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
If the rain begins after 2-4 hours from concrete placement, the surface needs to be covered; otherwise, the concrete surface will suffer damages. If rains pound on concrete 12 hours after placement, the likeliness of any damage is negligible.
To put it simply, the goal is to keep the concrete saturated during the first 28 days. The first 7 days after installation you should spray the slab with water 5-10 times per day, or as often as possible. Once the concrete is poured the curing process begins immediately.
Concrete Strength
Measured in MPa (megapascals) concrete is capable of achieving variable strength depending on the desired application ranging from general groundwork and residential applications (20-25MPa) to commercial grade which typically requires a stronger concrete mix (32MPa+).
Your new concrete shed/garage floor should be a minimum of 25-mpa (concrete strength) with SL72 reinforcing mesh at 100mm thick.
The typical concrete mix is made up of roughly 10% cement, 20% air and water, 30% sand, and 40% gravel. This is called the 10-20-30-40 Rule–though proportions may vary depending on the type of cement and other factors.
For waterproof concrete: Concrete mix design depends on local requirements and / or local standards for watertight concrete systems. A concrete mix design with a minimum grade of 30 MPa is recommended.
Tech-Mix® Pre-Mixed 35 MPa Concrete is a well-balanced superior mix of Portland cement, stone and sand. This mix is ideal for work requiring concrete with a thickness of 5 cm (2”) or more. Clean surface to be repaired must be free of foreign matter. Dampen surface before pouring.
As a rule of thumb 20mph concrete is fine for foot traffic, I.e., footpaths and house slabs, depending on your sub base, whilst 25 mph is more appropriate for driveways and light traffic. 32mpa and 40mpa concrete is suitable for shed slabs and heavy traffic areas.
No special attributes are necessary for sidewalk concrete, but specifications should include the following information: strength (25 to 35 MPa), minimum cement content (333 kg/m3), maximum size of coarse aggregate (19 mm), slump (50 to 100 mm) and air entrainment (5.5 to 8%).
As for thickness, non-reinforced pavement four inches thick is standard for passenger car driveways. For heavier vehicles, a thickness of five inches is recommended. To eliminate standing water, the driveway should be sloped towards the street a minimum of one percent, or 1/8 inch per foot, for proper drainage.
So, the ideal season for pouring concrete is during the cool to moderate months of the year. Depending on where you live, this could be the spring, fall, or even the winter for individuals living in very warm locations. Ideally, the temperature should remain within 50 to 60°F for most of the day.
You should wait at least 24 hours before walking on your freshly poured concrete. However, make sure not to drag your feet, twist around on it, or let your pets with claws walk on it until later. Bikes, toys, and skateboards should also be kept away from the driveway.
Spray: To maintain the proper moisture levels, concrete should be sprayed with water frequently. This is known as moist-curing. Most specialists recommend watering the slab 5 to 10 times per day for the first seven days. Moist-cured concrete can be up to 50% stronger than dry-cured concrete.