Concrete is sold based on compressive strength. The first decision you will have to make when purchasing concrete is to choose your mix. Boro Sand & Stone Corp. offers mixes in 500 PSI (pound per square inch) increments from as low as 2000 PSI to as strong as 5000 PSI or more. The stronger the concrete mix, the higher the cement content. (Contact Boro for pricing)
Besides strength, another concern you need to address is what weight you need. Typically, slabs on grade or foundation walls should be placed with normal weight concrete. Sometimes, you may need a lightweight concrete, for example, an elevated slab. Boro sells lightweight concrete in both 3000 PSI and 4000 PSI mixes. Other options also include grout and flowable fill.
The most commonly used mixtures are 3000 PSI, 3500 PSI and 4000 PSI. A general rule of thumb is that any exterior work that you are doing such as a patio or a driveway which will be exposed to freeze/thaw cycles requires at least a 4000 PSI mix. Areas which are not exposed but also not temperature-controlled, such as garage floors, will require 3500 PSI minimum strength. Interior work is typically constructed with 3000 PSI concrete. Be sure to contact us if you need any additional advice or information on picking concrete mix.
For more information on admixtures, coloring, fiber-mesh reinforced concrete, retarders and accelerators, please see the next section, Admixtures.