What Is PCC In Construction? | PCC Grades | PCC Ratio | Plain Cement Concrete

Plain Cement Concrete, commonly referred to as PCC, is a fundamental component in civil engineering and construction. It serves as a foundational layer for various structures, such as floors, roads, and retaining walls. Unlike reinforced concrete, PCC does not incorporate steel reinforcement, limiting its load-bearing capacity.

PCC’s Role in Construction

The primary functions of PCC are as follows:

1. Protection Against Corrosion : PCC acts as a protective barrier, preventing direct contact between steel reinforcement and the soil. This is crucial as soil moisture can lead to corrosion of the reinforcement within Reinforced Concrete (R.C.C) structures.

2. Providing a Level Base : By offering a uniformly leveled surface, PCC facilitates the accurate layout of structures above it. This simplifies the construction process and ensures proper alignment.

3. Preventing Water Loss : PCC also safeguards against water loss from the R.C.C structure, as the earth has a tendency to absorb water from it.

Different PCC Grades

Various grades of PCC are employed based on their load-bearing capabilities. These grades are denoted by the letter ‘M’ followed by a number indicating the compressive strength after 28 days of curing.

Understanding PCC Ratios

The PCC mix ratio denotes the proportion of its components. For instance, the mix ratio of M15 concrete is 1:2:4. This means that one part of cement is mixed with two parts of fine aggregate (sand) and four parts of coarse aggregate.

It’s important to note that while nominal and standard mix ratios are provided by IS codes for various constructions, consideration should be given to the specific design and testing requirements of the project.

Methods of Mixing PCC

PCC can be mixed either manually or with the assistance of machines.

1. Hand Mixing : Hand mixing, typically practiced in rural areas and suitable for small quantities, involves a step-by-step process of blending sand, cement, and coarse aggregate. Ensure the base is free from debris before commencing the mixing process.

2. Machine Mixing : Machine mixing, on the other hand, is a highly efficient process. It reduces mixing time and ensures a more uniform mixture. This method is typically employed for medium-scale projects.

The machine mixing procedure involves several steps:

• Wet the internal surface of the mixer with 1-2 buckets of water.
• Place coarse aggregate, followed by sand and cement alternately.
• Dry-mix the ingredients for 2-3 minutes.
• Gradually add water, monitoring the mixture’s consistency.
• Pour the thoroughly mixed concrete onto a clean surface.

Applications of PCC

PCC finds widespread use in various construction scenarios, including:

• Establishing a sturdy foundation in the form of a rigid impervious bed.
• Canal construction.
• Creating durable flooring, pavements, and CC roads.
• Executing stone masonry works.
• Constructing retaining walls and storm drains.

Do’s for PCC Works:

• Ensure proper placement of PCC shuttering, without any gaps or leaks, maintaining exact size and thickness for uniformity.
• Add water according to the required water-cement ratio using a bucket in measured volumes.
• Clean the surface thoroughly before pouring concrete to avoid debris contamination.
• De-water excess water immediately during concreting.
• Level the concrete promptly after pouring.
• When dealing with large areas of flooring, establish multiple T points to achieve a uniform level.

Don’ts for PCC Works:

• Refrain from mixing concrete with bare hands.
• Never pour PCC without proper formwork in place.
• Avoid pouring concrete from a height exceeding 1.5 meters, as it may lead to segregation.
• Use smooth channels instead of crooked ones for a polished finish.
• Do not pour concrete if any material exceeds the prescribed ratio.

By adhering to these guidelines, PCC works can be executed efficiently and effectively in construction projects.