The primary component of any structure laid before we start placing the RCC component is PCC. PCC stands for plain cement concrete which is a mixer of cement, sand and crushed gravel with optimum quantity of water. Plain cement concrete is laid on the soil surface to prevent the reinforcing of concrete from coming into direct contact with soil.
In this blog we will discuss about the importance of PCC, advantages and limitations of PCC in construction industry and what should we take care of before we laid it and site preparation and post working steps that should be taken like curing, cracking and if there’s any major issues.
PCC vs RCC:-
Plain Cement Concrete (PCC)
- is a basic form of concrete made from a mixture of cement, aggregates, and water. It is known for its simplicity and cost-effectiveness, making it suitable for projects where tensile strength is not a critical factor. PCC is typically used in foundations, flooring, based of any components and non-structural elements due to its compressive strength and ease of preparation.
Reinforced Cement Concrete (RCC)
- On the other hand, has steel reinforcement bars or mesh within the concrete mix to provide additional tensile strength and ductility. This reinforcement allows RCC to withstand greater loads and stresses, making it ideal for structural components such as beams, columns, slabs and bridges. RCC’s ability to resist bending and cracking under tensile forces sets it apart from PCC, broadening its application in modern construction.
Composition of PCC
1. Basic Ingredients
(a) Cement :-
- Cement is a key ingredient in concrete used to bind material together and provides durability, strength and long term stability. Most common types of cement is OPC and its constituent and properties are explained in our blog also.
Read,
Cement Unveiled : Unpacking Constituents, Properties, Functions And Hydration
(b) Aggregates (fine and coarse) :-
- Aggregates are essential components in the production of concret, are fine sand and coarse aggregate made from crushed stones, gravels, etc. They provide volume, stability, resistance to wear or erosion, and other desired physical properties.
(c) Water :-
- Water in concrete, playing several essential roles in the mixing, setting, and hardening processes. The quality and quantity of water used in the concrete mix significantly affect the properties and performance of the final product.
2. Proportions and Mixing :-
Standard mix ratios for PCC is generally M5 or M7.5 grade, can be used based on the requirements of project. Where M stands for Mix and the number represent standard compressive strength of concrete at 28 days in N/mm².
The mix proportion ratio for M5 is 1:5:10 means for every 1 m³ of concrete there is 1 part of cement is used with 5 parts of sand and 10 parts of coarse aggregate. Similarly in M7.5 ratio, proportion is 1:4:8.
The method of mixing for this ingredients can be done with the help of RMC plant or in field, it is possible with hand mixer also.
Properties of PCC
1. Compressive strength :-
- The compressive strength of PCC is very low and can be modified with the help of adhesive or admixtures. Generally we use M7.5 or M10 for it so compressive strength of PCC is 7.5 Mpa or 10 Mpa. Cooperatively it is used for the work where no heavy loads are acting so no need of the greater strength.
2. Workability :-
- Workability of concrete is the ease with which concrete can be mixed, transported, placed, compacted and finished without segregation. Workability of PCC is relatively higher than other concrete grade.
Applications of PCC
Role of PCC in building foundations is :-
- It provides a level and stable surface for placing reinforcement and the main concrete foundation.
- It prevents the corrosion of reinforcement by stopping direct contact of soil or moisture.
- It helps in distributing the load of the super structure evenly over the foundation base.
Use in constructing roads, driveways and flooring.
Advantages of PCC
1. Cost-Effectiveness :- Economic benefits of using PCC in construction projects.
2. Ease of Preparation :- Simplified preparation process compared to other types of concrete.
3. Improved Stability :- Provides a solid and even base for further construction work enhancing overall stability.
Limitations of PCC
1. Lack of Tensile Strength :- Concrete is a material which best for the compressive strength, it has great compressive strength but low tensile strength. In PCC we don’t use reinforcement so it is weak in tension.
2. Shrinkage and Cracking :- It can shrink as it cures and dries, leading to cracks.
3. Limited Application :- Due to low tensile strength and flexibility, it is not advisable to use it in the structure where significant amount of tensile load is subjected like beam, column and slab.
4. Heavier Weight :- PCC structures are relatively heavy, it requires more support. It can increase the overall cost of project.
5. Porosity :- It is very porous as the use of quantity of coarse aggregate are increasing. Significant methods can reduce the porosity but also increase the cost.
Construction Process of PCC in Foundation Work :-
It involves several steps to ensure proper preparation, mixing, placing, compacting, and curing of the concrete.
- Site preparation can be done by clearing the area of any debris, vegetation or loose soil. Excavate the foundation trench to the required depth.
- Install formwork to shape the PCC as per the design requirements.
- Prepare the PCC mix using a proper ratio of cement, sand and aggregate with the required amount of water.
- Casting the prepared formwork, ensuring it is evenly distributed.
- Compact the PCC using appropriate tools like tampers or vibrators to remove air pockets.
- Level the surface using a muster or trowel to achieve a smooth finish.
- Properly cure it by keeping it moist for at least 7 days to achieve the desired strength.
In the end it is a component used in limited construction projects but it enhances the strength of footing or flooring.
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