Properties and Applications of Different Types of Concrete
Regular concrete, or just concrete, is the type of concrete found in most home improvement stores. It has a fair amount of strength in compression, and can be used for a variety of cosmetic and structural uses. It is formulated using sand and cement, and can be premixed or mixed by the user. After the right mix is achieved, it is combined with water and used as intended.
High strength concrete can withstand far more pressure than regular concrete High strength concrete is created in part by lowering the water to cement ratio. The aggregate must be carefully chosen for this type of concrete, weaker aggregate could cause loss in the overall strength of the concrete. High strength concrete may also contain silica fume. This material prevents the formation of free calcium hydroxide crystals, which can affect the overall strength of the concrete.
Although high strength concrete is strong, it has reduced workability. Construction workers who pour high strength concrete must work quickly to get it into place. This is a particular difficulty when the concrete is being reinforced with steel. There are additives that are often used to increase workability in high strength concrete.
Self compacting concrete is a concrete that is used to reduce labor costs. When pouring regular or high strength concrete, the air in the concrete must be removed by using vibration on the outside of the formwork. Self compacting concrete can cut labor costs in half, and reduces the stress on the formwork, so it can be reused even more times. If possible, self compacting concrete is used in most building applications in the United States, where labor is a high percentage of the total cost of construction.
Pervious concrete is a concrete that allows a small amount of air or water to pass through the material. Someone in the building industry may refer to pervious concrete as “no fines”. This is because pervious concrete does not have the fine aggregate used in other building application. Because the aggregate used in pervious concrete are larger, the spaces between the aggregate are also greater. If significant cement is used to bind the larger aggregate together, there are still small holes within the concrete that allows water and air to pass through.
This type of concrete has a reduced strength, but many formulations provide enough strength to meet the needs of a variety of applications. Pervious concrete is often used to address environmental concerns about the affect of concrete on the environment. Regular concrete has little porosity, which prevents water from reaching the ground and increasing run off. By using pervious concrete, some of the water is able to go through the concrete and into the groundwater supply. The Environmental Protection Agency has encouraged the use of pervious concrete when other methods of preventing storm water run off is impractical.
Concrete has been used for thousands of years by a variety of peoples. Pyramids in China were constructed using a primitive form of concrete, and many people are familiar with the fact that the Romans used a form of concrete that is similar to the type we use today. As the needs for concrete change, the types of concrete also alter to conform to the environment around us.
