Why we provide PCC in Every construction & Notes

The term PCC stands for plain cement concrete. The mixture of cement, sand and coarse aggregate are generally called plain cement concrete (PCC). . It is also defined as Cement Concrete or Blinding Concrete.

The main reason of providing PCC is to provide a rigid impervious bed to RCC in the foundation before starting any RCC or masonry work directly on the excavated soil, PCC is done to form a leveled surface and to avoid laying concrete on soil directly so as to avoid mixing with soil and also to prevent soil extracting water from RCC thereby weakening it.

How do you calculate the quantity of cement in PCC ?

CEMENT QUANTITY IN M 10 :-

Step 1:-

Mix proportion of concrete 
For example M 10 = 1:3:6 (cement : sand : aggregate)

Step 2:-

• Dry volume = Wet volume x 1.54 (You can also take it as 1.50 to 1.55, But it became standard practice to considering 1.54 as multiplication factor)

• Quantity of cement or sand or aggregate = (Dry volume x cement or sand or aggregate ratio)/(sum of ratio)
• Density of cement = 1440 kg/m3
• 1 bag = 50 kg cement

Step 3:-

Dry volume = 1 x 1.54 = 1.54 m3

Cement = (1.54 x 1) /(1+3+6) = 1.54/10 = 0.154 m3

Weight of cement = 0.154 x 1440 =221.76 kg

No. of bag = 221.76 / 50 = 4.4352 bags

Note :-

• Portland Pozzolona cement (PPC) is normally used for Plain cement concrete.
• Compressive strength od PCC varies from 200 to 500 kilogram/square centimeter
• The size of the aggregate used for PCC varies from 10 mm to 40 mm depending on where they are to be used.
• For PCC slump 75 mm to 100 mm may be allowed for foundation work.
• The proportioning is done based on the requirement or given specification. Generally 1:2:4 or 1:3:6 mix is used.
• In volume batching, coarse aggregate and sand shall be measured by measuring box of 30cmx30cmx38cm of a suitable size equivalent to one bag cement of 1/30 m³or 0.035 m³.
• The quantity of water to be used for each mix of 50 kg cement to give the required consistency shall be as follows:

1. Not more than 34 lit – 1:3:6
2. Not more than 30 lit – 1:2:4
3. Not more than 27 lit – 1:1 ½:3
4. Not more than 25 lit – 1:1:2

• The PCC is laid in the layers of not more than 150mm thick 
• After 24 hours of laying PCC, moist the concrete surface by flooding with water or by covering with moist gunny bags at least for seven days.
• A strength of PCC is defined as compressive strength after 28 days, expressed as M15, M20, where M stands for Mix and 15 stands for 15 N/mm² compressive strength at 28 days.
• Do not pour concrete in the pit from a height of more than 1.5 m.
• Do not allow extra cement mortar on top of PCC. for smooth finishing.