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The main difference between lean and PCC concrete is that lean concrete contains less cement compared to the water content present in it. This means, when compared to plain cement concrete (PCC), the lean concrete has a smaller ratio of cement to water content.
Features of Lean Concrete
A concrete with cement content less than about 10 % of the total contents can be called lean concrete. More the aggregate to cement ratio, the leaner is the concrete. So, in this type of concrete, less amount of paste is available to provide lubrication per surface area of the aggregates. This hence restricts the mobility of the aggregate in the mix.
Lean concrete serves the purpose of providing a uniform surface to the concrete foundation. This also helps to prevent the direct contact of the foundation concrete from the soil. This is a good choice to provide a flat bottom for a terrain that is uneven or dirty.
As the lean concrete uses a lesser amount of cement, it is used in fillings or under the foundations so that the structure is protected from the soil.
A very leveled surface over which a foundation type can be placed is mainly made with lean concrete.
Protecting the foundation from the attack of moisture and chemicals in soil by having a layer of lean concrete in between the structure and soil is a widespread application.An example of lean concrete is the mix 1:4:8 with a cement content of 7%.
Features of Rich and Normal Concrete
Normal concrete has a cement content of more than 10 and less than 15%. A plain cement concrete with a mix ratio of 1:2:4 is normal concrete with cement content about 14%. Normal concrete is mostly used in damp proofing course, R.C.C, and floor finishing.
Rich concrete has a cement content of more than 15%. A P.C.C mix of 1:1.5:3 is an example of rich concrete with a cement content of 18%. This concrete is used for the construction of small structural members that can support heavier loads.
Also Read: 23 Types of Concrete