How Much Sand & Gravel Do I Need to Mix With a 94 lb. Bag of Portland Cement?

Specfic Guidelines

To create concrete using Portland cement and a medium-sized gravel with an aggregate size of 3/4 inches, mix one part Portland cement, two and half parts sand and two and half parts gravel. This works out to 94 pounds of dry cement, 235 pounds of sand and 235 pounds of gravel. To this mix add 6 to 9 gallons of water. This will yield enough concrete to cover 27 cubic feet.

Bags of Portland cement are sold in various sizes. If you plan to mix concrete, it is handy to have a general guideline for how much sand and gravel you will need in proportion to the amount of Portland cement you have on hand. The basic recipe for making cement is one part Portland cement, two and a half parts sand and one and a half to three parts gravel. The amount of gravel depends on the size of the rocks in the gravel.

You will need more or less gravel depending on its aggregate size. For gravel measuring 3/8 inch, use one and a half parts to the cement and gravel mix (141 pounds if using a 94 lb. bag). Gravel sized 1/2 inch requires two parts (188 pounds). One inch gravel raises it to two and three-quarter parts ( 259 pounds). For 1 1/2 inch gravel you will need three parts in the mix (or 282 pounds).

You will need to rent a mixer to combine this amount of material. Concrete is easier to work with and produces a better final product if you work in temperatures ranging from 60 to 70 degrees. Add about 1 gallon of water to wet the inside of the mixer and keep down the dust from the cement. Follow this with the cement and sand. Let this mix for five minutes before adding the gravel and enough water to make the mix workable. Depending on how dry your sand and gravel are, this will take 5 to 9 more gallons of water.