The base in concrete construction is the layer between the sub-grade (existing soil) and the concrete slab. The base (usually a crushed stone material) acts as a support between the dirt and slab, and ultimately, reduces cracking of the slab.
Imagine placing a pane of glass on a mattress. Now, imagine standing on that pane of glass. It's going to crack and break, right? Essentially the same thing is going to happen to your concrete slab if it does not have a proper base to support it over its lifespan. The base provides a few important functions:
The base in concrete construction is usually a form of crushed stone. Most concrete contractors want a mix of coarse and fine aggregate to create a compactable base that is going to be safe for settlement and drainage. Crusher run (a mix of crushed stone and stone dust) is one of the best base materials for concrete flatwork.
There are an endless number of concrete finishes. Today we will cover what can be found in the majority of residential homes, to help homeowners obtain the function and aesthetics they wish to achieve.
The broom finish is what you find on the sidewalk when walking through your neighbourhood. This finish simply has a broom run across the top of concrete while the concrete is still slightly wet, to give it a textured non-slip finish. Broom finishes are typically applied to exterior (air entrained) concrete that will be exposed to weather.
The hard trowel finish can likely be found in the garage of your own home as well as the floors of large commercial buildings such as Wal-Mart or Costco. This finish takes longer to achieve than the broom finish due to the need to make multiple passes with a steel trowel along the surface of the slab. Both hand trowels and ride on trowel machines are used to give the concrete a smooth slick finish in this scenario. Hard trowelled finishes are typically only applied to non-air interior concrete mixes. The presence of air can cause delamination and blistering during the lifespan of the concrete.
Pea gravel concrete finishes require a completely different mix design which typically consists of 50% sand and 50% pea gravel. Pea gravel mixes are mostly found in residential driveways and patios. In order to achieve the exposed finish of pea gravel, a plastic sheet is placed on top of the concrete before a pressure washer is used to remove the surface retarder. The colour of the rock is dependent upon your rock supplier.
Stamped concrete offers an endless number of finishes depending on the stamp design the homeowner chooses. Options include brick, wood plank, and tile patterns, among others. Stamped concrete is the most expensive form of concrete finishing due to the amount of time involved to carefully and uniformly place the stamped pattern. Stamped concrete, however, achieves a highly aesthetic look that is perfect for applications such as outdoor patios.