Weight of Ready Mix Concrete

Types

• One important factor in determining concrete's weight is its density -- the amount of substance per unit volume. The density of concrete mixtures varies depending on the blend you purchase. Manufacturers sell "lightweight" varieties with densities ranging from 90 to 110 lbs. per cubic foot, and "heavyweight" varieties with densities exceeding 300 lbs. per cubic foot. Most standard concretes, however, run about 150 lbs. per cubic foot, so you can generally take this figure as a good rule of thumb unless you have purchased a variety with a greater or smaller density.

Volume

• The next important consideration is the amount of concrete you buy. Quantities of concrete are usually measured in cubic yards or cubic feet, which are units of volume. If you multiply the density of the concrete by the volume, you'll get the total weight. If you just bought 100 cubic feet of concrete with a density of 150 lbs. per cubic foot, for example, you would multiply 150 times 100 to obtain a total weight of 15,000 lbs. Ask your concrete batch mixer for a specific density and weight report for the concrete you'll use.

Problems

• As you can see from this figure, while concrete has many desirable properties as a construction material, its sheer weight can also be daunting. One of the benefits of buying ready-mix concrete is that the concrete is delivered to you premixed by the cement truck, so depending on the circumstances, you may avoid some of the problems you would face if you tried to transport and mix all the concrete by yourself.

Considerations

• It's a good idea to order a little more concrete than you actually need in case you run short. The National Ready Mix Concrete Association recommends you use a margin of 4 to 10 percent. It's also important to realize that ready-mix concrete must be used soon after arrival. It's delivered in a fluid state, which makes it easier to distribute; but if you wait too long it could lose its water volume.