Plain Cement Concrete (PCC) in Construction: A Complete Guide
Plain Cement Concrete (PCC), also known as โcement concreteโ or โmass concrete,โ is one of the most commonly used construction materials worldwide. It forms the backbone of nearly every structure by providing a strong, level base for further construction activities.
In this comprehensive blog, weโll explore everything you need to know about PCC in construction โ from its definition and materials to its mix design, application methods, advantages, and much more.
What is PCC in Construction?
Plain Cement Concrete (PCC) is a construction material composed of cement, fine aggregates (sand), coarse aggregates (gravel or crushed stone), and water, mixed in a specific ratio and poured into a formwork to set into a strong mass.
PCC is used without any steel reinforcement, which differentiates it from Reinforced Cement Concrete (RCC).
PCC provides a leveling base and a firm surface for laying structural members such as footings, columns, flooring, and slabs. Itโs also used in pavements, roads, and as a blinding layer over the soil to avoid direct contact with reinforcement.
Objectives of Providing PCC
- Leveling Surface: To create a uniform and level surface over uneven or soft soil.
- Preventing Reinforcement Corrosion: Acts as a protective layer to stop moisture ingress into RCC members.
- Improving Load Distribution: Helps distribute the structural load evenly to the subsoil.
- Providing a Clean Working Surface: Offers a neat and clean area for reinforcement placement and formwork assembly.
- Isolating Structural Members from Soil: Prevents direct interaction of the soil with foundation elements.
Materials Used in PCC
The quality of materials directly affects the strength and durability of PCC. Hereโs a breakdown of the key materials:
| Material | Function |
|---|---|
| Cement | Binds aggregates together after hydration. Ordinary Portland Cement (OPC) 43/53 grade is usually used. |
| Fine Aggregate | Fills voids between coarse aggregates and improves workability. Clean river sand or manufactured sand (M-sand) is commonly used. |
| Coarse Aggregate | Provides compressive strength and bulk to the concrete. Crushed stone or gravel of 20mm downsize is standard. |
| Water | Initiates chemical reaction for cement hydration. Must be clean and free of impurities. |
Common Mix Ratios for PCC
PCC is prepared in various mix ratios depending on the application and required strength. These mix ratios are based on volume batching:
| Mix Ratio | Description | Use Case |
|---|---|---|
| 1:3:6 | 1 part cement, 3 sand, 6 aggregates | Used for foundations with low load requirements |
| 1:2:4 | 1 part cement, 2 sand, 4 aggregates | Flooring and non-structural members |
| 1:4:8 | 1 part cement, 4 sand, 8 aggregates | Blinding layers, leveling courses |
Note: The mix ratio may be adjusted depending on the structural design, local codes, and construction requirements.
Thickness of PCC
The typical thickness of PCC depends on its location and purpose. Common thicknesses include:
- 100 mm (4 inches) for light-duty flooring and residential use.
- 150 mm (6 inches) under footings and for road sub-bases.
- 200 mm or more for industrial floors and high-load areas.
Procedure for Laying PCC
Laying PCC must be done with care to ensure strength, durability, and longevity. Hereโs a step-by-step overview:
1. Site Preparation
- Excavate the area to the required depth.
- Remove organic material, loose soil, and debris.
- Compact the soil manually or with mechanical tools.
2. Formwork and Shuttering
- Provide wooden or steel shuttering to confine concrete.
- Ensure formwork is level, leak-proof, and treated with shuttering oil to avoid sticking.
3. Base Layer (if required)
- A 15โ20 mm thick dry sand or aggregate cushion may be laid to improve drainage.
4. Mixing of Concrete
- Mix concrete either manually on a platform or using mechanical mixers.
- Use clean water and measure ingredients precisely.
5. Placing of Concrete
- Pour concrete immediately after mixing.
- Spread evenly using shovels and tamping rods.
6. Compaction
- Use vibrators or tamping tools to remove air pockets and voids.
7. Leveling and Finishing
- Level the surface using screeds and trowels.
- Finish as per design โ rough, smooth, or broom finish for floors.
8. Curing
- Begin curing after 24 hours by spraying water or covering with wet hessian cloth.
- Continue for 7 to 14 days, depending on environmental conditions.
Curing of PCC
Curing is crucial for hydration and strength development. Improper curing leads to cracking, reduced durability, and surface defects.
Curing methods include:
- Ponding
- Wet coverings
- Spraying or sprinkling water
- Curing compounds (for large or inaccessible areas)
Where is PCC Used?
PCC is widely used in the following areas:
- Under footings and foundations
- As a base for floors and slabs
- In road construction
- For boundary walls
- Under column footings
- As bed concrete under RCC members
Advantages of PCC
- Economical: Cost-effective for non-structural elements.
- Workability: Easy to mix and place manually or with machinery.
- Reduces Moisture Penetration: Acts as a barrier against soil moisture.
- Durability: Withstands moderate loads and environmental exposure.
- Improves Bonding Surface: Enhances adhesion of further concrete or masonry work.
Limitations of PCC
- Not Suitable for High-Tensile Loads: Cannot be used where tensile strength is required (use RCC instead).
- Cracking Risk: Without proper curing or joint control, cracks may appear.
- Heavier: Adds dead weight without structural contribution.
PCC vs RCC
| Criteria | PCC | RCC |
|---|---|---|
| Reinforcement | No steel reinforcement | Contains steel bars or mesh |
| Load Capacity | Handles compressive loads only | Handles compressive and tensile loads |
| Cost | Lower cost | Higher due to steel and labor |
| Use Cases | Base layers, flooring, pavements | Beams, columns, slabs, foundations |
| Durability | Moderate | High durability and structural integrity |
Tips for Quality PCC Work
- Always use fresh cement and clean aggregates.
- Maintain water-cement ratio for strength (typically 0.5).
- Mix properly to ensure uniformity.
- Compact thoroughly to eliminate voids.
- Cure consistently to prevent early drying and cracking.
- Avoid construction in extreme temperatures without protection.
Common Mistakes in PCC Work
- Using dirty or oversized aggregates
- Improper mix ratio leading to weak concrete
- Skipping compaction
- Insufficient curing
- Lack of control joints in large surfaces
- Pouring on unprepared or loose soil
Avoiding these can significantly improve the life and strength of the concrete.
Conclusion
Plain Cement Concrete (PCC) plays a foundational role in construction, offering a stable base for structural members and enhancing the overall durability of the building. Whether youโre working on a residential, commercial, or infrastructure project, understanding the composition, procedures, and best practices of PCC is critical to ensuring long-term structural performance.
By adhering to proper mix ratios, site preparation, curing, and execution, construction professionals can deliver cost-effective, durable, and safe concrete works that meet both functional and aesthetic standards.
FAQs About PCC in Construction
Q1. What is the difference between PCC and RCC?
PCC contains no steel reinforcement and handles compressive loads only, while RCC has steel bars and handles both tensile and compressive stresses.
Q2. What is the minimum thickness of PCC?
The minimum thickness generally ranges from 100 mm to 150 mm, depending on the load and site conditions.
Q3. Can PCC be used for structural elements?
No. PCC is not suitable for structural members requiring tensile strength. Use Reinforced Cement Concrete (RCC) for such applications.
Q4. What is the curing period for PCC?
The standard curing period is 7 to 14 days, depending on weather conditions and concrete grade.
Q5. What grade of cement is used in PCC?
OPC 43 or OPC 53 grade cement is typically used in PCC works for better strength and durability.
Q6. Why is PCC used below footings?
PCC provides a level, clean, and strong base to distribute loads evenly and prevent reinforcement corrosion from ground moisture.
Q7. Can I mix PCC manually?
Yes, for small-scale work. However, mechanical mixing ensures better consistency and is recommended for larger volumes.
