Concrete and Cement are often thought of as the same product but actually Cement is just one part of Concrete.
Concrete is a mixture of Aggregates and Binders (Rocks and Cement).
Depending on your needs you can use larger or more aggregate to get a harder product or you can use smaller aggregate to allow the mix to flow.
This difference is easy to understand when you compare the tough but formable sandy mixture that is shot onto Swimming Pools and the much stronger Rocky mixes that are used for foundations and roadways.
Portland Cement is the binder material in Concrete and is made of
60% lime, 25% silica, 5% alumina, and small amounts of iron oxide and gypsum.
The Lime comes from limestone, oyster shells, chalk, and clay.
Silica and Alumina come from shale, clay, silica sand, slate, and blast furnace slag. Iron oxide comes from iron ore, pyrite, and other materials.
Concrete is made of
• Water
• Portland Cement
• Sand
• Intermediate Aggregate (3/8″ – 1/16″ Pea gravel)
• Coarse Aggregate (gravel, crushed stone)
Placing Orders or Buying Concrete
When ordering or buying concrete you will want to know the correct PSI or pounds per square inch Rating that is needed.
If you are purchasing Bags of concrete you will probably see 3 different types. General Purpose, High Strength and products with special additives.
Additives are often useful and can help in adhesion of new concrete to old or can allow you to pour in lower temperatures and reduce cracking.
For most projects you will want a general purpose Bag or Delivered product.
Water
Water is important for 2 reasons. First it provides activation of the Cement and also lets you pour the product into forms.
The lowest percentage of water to allow activation and curing is always the best because as the Concrete Cures and Drys the water in the concrete will form hollow pockets and reduce the final strength.
On very Hot days evaporation is also a serious problem.
All Concrete should be allowed to cure for about 7 days.
Mortar
Mortar is a type of concrete but the aggregate is only sand. Mortar is used for Tile, Stone and Brick work to bond the finish material to a substraight and to each other. Like Concrete the mixture should have the lowest water content possible however Mortar used for Tile work will have more water to allow the trowel to float the area level and produce notches so the Tile can be set to the proper height.
Mortar mixtures can come ready to apply in buckets or premixed in bags dry. You can also mix your own mortar by using a 5:1 sand:portland cement mix.
Stucco is also a type of mortar and there are other Cement / Concrete mixtures that can be used for a variety of reasons in your home and business.