Plain cement concrete (PCC) is used to provide rigid impervious bed to RCC in foundation where the earth is soft and yielding. PCC can be used over brick flat soling or without brick flat soling.
Plain cement concrete can also called only “cement concrete (CC)” or “binding concrete”.
Materials used for producing PCC:
Cement: we generally use Portland cement as bonding material in PCC.
Fine Aggregate: Sand is used as fine aggregate. The FM of sand should be 1.2 to 1.5.
Course Aggregate: We normally use brick chips for producing PCC. Stone chips can also be used for this purpose. The size of the course aggregate is 20mm downgrade.
Water: Pure drinkable water should be used in PCC.
We normally use following tools for producing Plain Cement Concrete-
- Wooden or Steel rammer
- Mixture machine (if any)
The thickness of PCC is normally 50mm over Brick Flat Soling (BFS). If we don’t use BFS below PCC then the thickness should be 75mm. when the PCC is used in car park area then the thickness should be 75mm over BFS.
Material proportion for PCC:
The proportion of cement, sand and brick chips by volume in foundation or basement is 1:3:6. But, in car park area, the proportion should be 1:2:4.
Procedure of manufacturing PCC:
If you want to use ready-mix concrete then you should skip this step. If you want to produce PCC by mixture machine then click “How to mix concrete by mixture machine”. If you don’t have concrete mixture machine and want mix concrete by hand see “how to mix concrete by hand”.
Placing and Compaction of PCC:
- Make sure brick soling/sand bed level for PCC is ok.
- Make form work for PCC with wooden plank as per specified dimentions.
- Clean dust or foreign or loose earth from concreting area.
- Spread polythene over the bed of PCC.
- Make level pillars of fresh concrete in the area at suitable intervals but not more than 2m c/c both ways.
- Place the concrete gently (don’t through) from one side. Use the mixed concrete within 45 minutes after the water is added.
- Use wooden rammer for compaction and finishing of PCC.
- Make the surface of PCC roughen for joining future work before the concrete become harden.
Curing of PCC:
After 24 hours of laying PCC, moist the concrete surface by flooding with water or by covering with moist gunny bags at least for 7 days.
Checking and Inspection:
- Check the dimensions of form work of PCC before mixing concrete.
- Check polythene sheet is laid over PCC bed.
- Check the concrete slump (maximum slump should be 75mm)
- Check the thickness level of PCC before casting by putting steel pegs in concreting area or putting level pillar of fresh concrete at suitable distance.
- Check the finish level of PCC by thread fixing with nails in form work.
- Inspect if the concrete is placing gently.