PCC Concrete: What Are the Benefits and Uses?

PCC stands for Plain Cement Concrete. PCC is a combination of cement, sand-like fine aggregate, and coarse aggregate. Another name for it is blinding concrete or cement concrete (CC). To prevent the reinforcing of the concrete from coming into direct contact with the soil and water, concrete is poured on the soil’s surface before pouring the foundation.

Cement, fine aggregate (sand), and coarse aggregate without steel are combined to create plain cement concrete. To keep the concrete’s reinforcement from coming into contact with soil and water directly, PCC, a crucial building component, is placed on the earth’s surface.

See also: Self compacting concrete (SCC): Know everything about this type of concrete

 

PCC concrete: Characteristics of Plain Cement Concrete 

• Compressive strength: 200 to 500 kilogrammes per square centimetre
• Tensile strength: 50 to 100 kilogrammes per square centimetre for tensile strength
• Density: 2200 to 2500 kilogrammes cubic metre density 
• Stability: Excellent 

see also about: rmc concrete

PCC concrete: Properties 

Strength

• High compressive strength is required for the PCC.
• Tensile and shear strengths should be between 8-12 % and 8-10 % of compressive strength, respectively.

The following factors affect the PCC’s compressive strength:

• Cement Content
• Water Cement Ratio
• Method of mixing, placing, compacting, and curing.
• Quality of the materials used
• Age of the concrete.

learn about Cement test

Durability 

For PCC to be resilient and durable, it must be able to withstand chemical and environmental effects.

See Also:What is slump test?

Workability 

• PCC should be very feasible.
• Mixing, handling, and transporting it should be simple.
• Bleeding and segregation should not be present.
• Slump testing can be used to determine workability.

Fire Resistance

To avoid issues like burning, spalling of concrete, etc., PCC should be extremely fire resistant.

known about about all about: Stone masonry: A complete guide

PCC concrete: Placing and compaction of PCC

• Make sure the PCC is at the ideal brick soling/sand bed level.
• Build the PCC formwork using wooden boards to the required dimensions.
• The area where concrete is being poured shouldn’t include any dust or unwanted foreign objects.
• Polythene should be used to cover the PCC bed.
• Create level pillars of fresh concrete in the space with the appropriate spacing, but not more than 2 metres in either direction.
• From one side, gently place the concrete. After the water is added, the mixed concrete must be applied within 45 minutes.
• The PCC should be compacted and finished with wooden rammers.
• To facilitate future work before the concrete solidifies, the PCC surface should be rough.
• PCC must be applied to the concrete surface and left there for 24 hours before it may begin to cure. Alternatively, the surface can be covered for at least seven days using damp gunny bags.

See: also all about workability of concrete

PCC concrete: Ingredients of PCC in construction

The basic components of plain cement concrete are listed below.

1. Coarse aggregates

Any foreign granite or elements similar to stone, including hard grit, dirt, and other foreign materials, should not be present in the coarse aggregates used in PCC. The size of the stone ballast will be 20 mm and smaller. Every piece of coarse material needs to be kept in a 5 mm square mesh and graded properly so that voids don’t transcend 42%.

2. Fine aggregates

The fine set must be composed of coarse sand with hard, pointed, and angular grains and must pass through a mesh screen with a 5 mm square opening. The sand must be clean, of standard specifications, and free of organic debris, dust, and grime. There won’t be any utilisation of sea sand.

3. Cement

Plain cement concrete is frequently made with Portland Pozzolana Cement (PPC). It should meet the requirements in terms of fineness, have the necessary tensile and compressive stresses, and conformance to the specifications.

4. Water

The water will be crystal clear and largely free of impurities, including oil, chemicals, oxidising agents, minerals, and plant growth. In general, water needs to be at least 6 on the pH scale.

See also: What is the specific gravity of cement?

 

PCC concrete: Proportioning of Plain Cement Concrete

• The proportioning is carried out following the requirement or provided specification. Typically, a 1:2:4 or 1:3:6 mix is used.
• The material can be measured using either volume batching or weight batching.
• A measuring box that measures 30 cm by 30 cm by 38 cm, or 1/30 m3 (or 0.035 m3) of cement, should be used to measure coarse aggregate and sand when combining ingredients by volume.
• Sand should be measured in terms of dry volume.
• Sacking, ramming, or hammering shall not be done while gauging the aggregate.

 

PCC concrete: Making of PCC Concrete

The steps for creating plain cement concrete are as follows (PCC)

• Selection of Ingredients
• Mixing of Ingredients
• Transportation and positioning 
• Compaction of concrete
• Finishing and curing of concrete

 

PCC concrete: Mixing of Plain Cement Concrete

Concrete production is the process of making concrete which involves combining many components, including water, aggregate, cement, and any additives. Concrete production is time-sensitive.

Workers must place the concrete as soon as it is mixed before it hardens. In today’s world, a concrete plant, also known as a batch plant, is a big industrial building where the majority of concrete is produced.

Different concrete admixtures are needed for various projects. Use the proper way of mixing concrete for the intended use and application if you want effective outcomes.

The following three concrete mixing techniques are used to produce concrete that is efficient and of high quality.

1. Concrete mixing by hand (mixing concrete manually without a mixer machine)
2. Automatic concrete mixing (mixing concrete with a mixer machine)
3. Pre-mixed concrete (mixing in an automatic or semi-automatic batching plant)

Both manual and mechanical methods can be used to mix PCC:

• Concrete mixing by hand (mixing concrete manually without a mixer machine)
• Only small-scale projects are permitted to use hand-mixing for PCC.
• The base used for mixing the concrete must be either a steel platform or a perfectly clean, watertight slab.
• Coarse aggregate is added after mixing sand and cement thoroughly.
• To achieve a uniform colour and consistency, water is lastly added and thoroughly blended into the mixture.
•  Lastly, water is added, and the mixture is mixed properly to gain an even colour and consistency.
• Automatic concrete mixing (mixing concrete with a mixer machine)
• Measured amounts of concrete, dried coarse aggregate, and fine aggregate need to be poured into the proper containers.
• The required amount of water must be added gradually while the mixing drum is still in rotation after the dry components have been mixed for at least 4 consecutive rounds.

• To obtain the desired water-cement ratio, the complete amount of water for mixing must be added before 25% of the mixing period has passed.
• For a plastic mixture with consistent colour, thorough mixing is required.

 

PCC concrete: Factors that influence the method of concrete mixing

• Location of the construction site with enough space for construction activities, such as densely populated urban areas.
• The amount of room available for mixing, batching, and storing aggregates for concrete.
• The volume of concrete required.
• The construction schedule is like the quantity of concrete required per hour or per day.
• The height at which concrete will be placed and the cost

 

PCC concrete: Laying of Plain Cement Concrete

• The PCC is laid in layers not thicker than 150mm. By repeatedly pulsating the PCC using mechanical vibrators, viscous concrete is produced.
• Manual compaction must be done whenever necessary with the use of wooden tamping rods to ensure that concrete is completely compacted and walked into the corners of the formwork.
• Within 30 minutes of adding water to the dry mixture, compaction must be finished before the initial setting process begins.

 

PCC concrete: Advantages of laying Plain Cement Concrete

• Cover blocks rest on a sturdy PCC, ensuring the necessary cover-to-bottom reinforcement.
• On PCC, reinforcement steel bars are never in contact with the ground soil, which may be chemically active and may soon cause steel corrosion.
• Easier installation of steel cages and increased productivity.
• Concrete does not stick to the ground soil(clay); nevertheless, PCC serves as a soil barrier and binds well to structural-grade concrete that has been overlaid.
• For the footing of the foundation, PCC Concrete is simple to install in a steel cage so that the rate of productivity at work increases.
• Together with the concrete soil of the footing, PCC Concrete serves as a barrier so that the footing concrete can adhere to the reinforcement and attain sufficient strength.
• PCC Concrete provides a finishing surface to serve as a cover for footing reinforcement.
• A foundation for formwork is provided by PCC concrete so that the footing formwork can be quickly, evenly, and firmly secured.

 

PCC concrete: Disadvantages of  PCC Concrete

• After being laid on the surface, PCC concrete quickly begins to dry.  Therefore, its surface needs to be finished right away.
• PCC Concrete cannot be stored in RMC trucks for an extended period of time.
• Other concrete elements cannot be constructed with increased PCC concrete.

 

PCC concrete: Curing of PCC

• Concrete that has just been laid down must be thoroughly secured to prevent it from weather and rain.
• The concrete must be covered with wet gunny bags, sand, or other materials to prevent quick drying after it has started to firm, which should take one to two hours after it has been laid.
• The surface must either be covered with weight-absorbent materials or immersed in water that is nearly 25mm deep just after the concrete has been set for 24 hours to cure.
• Curing must be done for at least fourteen days.

 

PCC concrete: Uses  

• Throughout history, concrete has been used for a variety of wonderful purposes, including the construction of buildings and other infrastructure.

• Nevertheless, concrete is still a common building material today. It is frequently used to build floors, large gravity dams, and column foundations.
• It is utilised in the construction of rigid pavement (reinforcement-less rigid pavement).
• PCC is utilised in the construction of small-scale canals.
• Some stone masonry projects also utilise it.
• To achieve a solid, even, and hard surface on the window and ventilator surfaces, PCC concrete is used.
• It is used to make pavements and for building basketball courts, tennis courts, etc.
• The cover blocks rest on a solid PCC therefore, the required cover for the lower reinforcement is ensured.
• While PCC serves as a soil barrier and is connected to structural grade concrete that has been fully overplayed, concrete does not bond with the soil of the earth.

 

PCC concrete: Dos & Don’ts of PCC Work  

 Dos

• The shuttering used in PCC projects needs to be precisely the right size and thickness.
• According to the w/c (water/cement) ratio, a specific amount of water needs to be added to a bucket of cement.
• Pour concrete when there is a greater depth using a chute or extra workers.
• Remove any loose material from the pit’s sidewalls to prevent soil or other materials from collapsing inside the pit when the concrete is being poured.
• When the water table is high, de-watering should be performed before PCC work.

Don’ts 

• Never mix the components on bare ground.
• It should not be permitted to perform PCC without formwork.
• The concrete surface needs to be levelled and compressed before pouring.
• Concrete should not be poured into the hole from a height of more than 1.5 metres.
• Avoid adding additional cement mortar on top of PCC, for smooth finishing.

 

FAQs:

Is it necessary that the area on which PCC is poured should be clean?

Yes, The area where concrete is being poured shouldn't include any dust or unwanted foreign objects.

What is the meaning of 1:2:4 PCC in concrete?

Proportioning is carried out in 1:2:4 for PCC. In mix design, the proportion 1:2:4 means, 1 part of cement is mixed with 2 parts of sand and 4 parts of coarse aggregate.