When combined, an 80-pound bag of dry concrete will weigh approximately 80 pounds. Divide the amount of weight required by 80 pounds to get the number of bags required to mix. In this case, you'll need about 10 bags of concrete.
Concrete is a heavy material. Therefore, it's important to use a reliable measuring tool when mixing or preparing concrete. A weight or scale is needed to ensure consistent results.
The type of cement used in concrete affects its weight. Ordinary portland cement weighs 40 pounds per cubic foot when dry. Concrete made with that much cement by volume would be very dense.
If you have access to steel reinforcing bars, you should use them when ready-mixing your own concrete. The extra reinforcement adds strength and durability to the finished product. Rebar is available in various sizes and shapes. It can be left inside the mixed concrete as long as it's not exposed to air for more than 30 minutes.
For most other applications, including repairing broken glass or filling in small cracks, 5 lb. Bags of concrete are sufficient. Such bags contain enough powder to mix with water to make one quart of concrete. This is enough to fill a 1-by-4-inch hole or layer about 3/8 inch thick.
Adding and subtracting. It is not always necessary to use precisely 60 pounds of concrete mix. Mix no more than you will need in one session. Concrete dries rapidly, and the mix will not last from job to job. If you require more than one 60-pound bag, increase the water appropriately.
The amount of water required depends on the type of cement used. The density of concrete is approximately 1,450 pounds per cubic foot; this means that it takes about 746 gallons of water per cubic yard to make a concrete slab 70 inches by 100 inches by 4 inches thick. The rate of absorption varies with the type of cement used, but generally ranges from 2 to 3 percent per hour. Cement mixes typically include some type of accelerant to speed up the setting process. As a rule of thumb, you should allow enough time for the mixture to become solid before it starts to smell bad. Some types of cements can emit gases that may be harmful if they are present in excess of allowable limits. As soon as you finish mixing the concrete, cover any exposed material with plastic wrap or place it in a cold area until the mix has set.
Water plays an important role in concrete durability. The water/cement ratio affects the strength and durability of the finished product. Concrete that is too dry (less than 15% water) will appear white and feel powdery when touched.
How many 80-pound bags of concrete are there in a yard? A cubic yard of concrete requires 45 bags of concrete mix. A cubic yard contains 27 cubic feet of concrete. So, if you were to pour a 4-foot by 8-foot by 2-foot slab of concrete, the total weight would be 720 pounds (362 kg). The volume of concrete required to cover that area is therefore 1,620 cubic inches (30.5 cm3), or 54 cubic yards.
There are 3280 square inches per square foot, so one square foot of concrete requires 5.1 ounces of water. If the slab was 8 feet wide instead of 4, the total weight would be 912 pounds (420 kg), and the volume of concrete required would be 1020 cubic inches (21 cm3), or 48 cubic yards.
The number of bags of concrete required will vary depending on the size of the bag used. For example, if each bag holds 20 pounds of concrete, then there are two sizes of bags available: small, medium, and large. If the slab is 4 feet by 8 feet, then it needs:
Understanding Concrete Weight Concrete comes in varying weights when purchased from a local hardware shop. When you take up a 90-pound bag, it will be 90 pounds. The additional weight from concrete is caused by the injection of water and air into the concrete when it is mixed. This makes concrete heavier than most dry materials, such as sand or gravel.
Concrete weight is important because it determines how many pounds of concrete can be placed in a single load or trailer. For example, if a company wants to place 100 yards of sidewalk, they would need 50 bags of concrete. Each bag weighs 45 pounds, so we need two people to carry them. Or we could use a power mixer, which mixes the concrete on site instead of transporting it to a job site.
The density of concrete varies depending on its composition but usually ranges from 2,000 to 3,000 pounds per cubic foot. This means that a cubic yard of concrete has a volume of 1,728 to 2,592 square feet. A standard size concrete slab weighs about 20,000 pounds and measures 60 inches by 96 inches.
The strength of concrete varies depending on its intended use but usually ranges from 3 to 30 MPa (50 to 350 psi). This means that the surface of a concrete slab should be able to support itself under normal conditions. But if it doesn't, there are cracks that can lead to corrosion and loss of structural integrity.
A 60-pound bag of hardened concrete yields 0.45 cubic feet. An 80-pound bag of hardened concrete yields 0.6 cubic feet. A 100-pound bag of hardened concrete yields 0.75 cubic feet.