What is Plain cement concrete or PCC concrete?

Plain cement concrete (PCC), also known as plain concrete, is a fundamental building material widely used in construction projects. It is a versatile and cost-effective material that provides the groundwork for various structures, including foundations, pavements, and flooring.

In this article, we will explore the components, mixing process, applications, advantages, limitations, and maintenance of plain cement concrete. Let’s delve into the world of PCC and discover its significance in the realm of construction.

What is Plain cement concrete or PCC concrete?

Plain cement concrete or PCC in construction is the hardened mass obtained from a homogeneous mixture of cement, sand, stone chips, and water in suitable proportion. In other words, the cement concrete in which no reinforcement is provided is known as plain cement concrete.
Plain cement concrete has good compressive strength, but a very little amount of tensile strength. Hence the use of plain cement concrete ( PCC concrete) is very limited in construction.

It is also known as Blinding Concrete.

Why plain cement concrete is required or purpose of plain cement concrete

The Purposes of Plain Cement Concrete in Construction are as follows:

To provide a strong and level base: PCC is commonly used as a foundation material for buildings, bridges, and other structures, providing a strong and level base for further construction activities.

To transfer loads: PCC can be used to transfer loads from the structure to the soil or rock below, which helps distribute the weight of the structure more evenly and prevent settlement or subsidence.

Prevention of water accumulation: It can be used to prevent the accumulation of water in the foundation and prevent damage to the structure over time.

Weathering and erosion resistance: It is a durable material that can withstand the effects of weathering and erosion. This is so it is suitable for use in outdoor structures such as retaining walls and pavements.

To provide a smooth surface for further construction: PCC can be used to provide a smooth surface for further construction activities such as flooring and tiling.

Construction cost reduction: PCC is a cost-effective material that is made from readily available materials such as cement, aggregates, and water, which helps reduce construction costs.

Overall, PCC is required in construction to provide a strong and durable base for further construction activities, control water accumulation, resist weathering and erosion, and reduce construction costs.

Where is plain cement concrete used?

Application of Plain cement concrete or uses of plain cement concrete

Plain cement concrete or PCC concrete is commonly used only in places where tensile loads are not acting on it (i.e., compressive loads are acting).

Generally, uses of plain cement concrete are-

• Plain cement concrete in Foundations: PCC is commonly used as a foundation material for buildings, bridges, and other structures, providing a strong and level base for further construction activities.
• Plain cement concrete in Columns and Beams: PCC is also used to make columns and beams in building construction. These structural elements can be reinforced with steel bars to increase their load-bearing capacity.
• Plain cement concrete in Pavements and pathways: PCC is used to create pavements and pathways in residential and commercial areas. It provides a strong and durable surface for foot and vehicle traffic.
• Plain cement concrete in Retaining walls: PCC is used to construct retaining walls that hold back soil and prevent erosion.
• Plain cement concrete in  Water tanks: PCC can be used to construct water tanks, as it is impermeable to water when properly cured.
• Plain cement concrete in Drainage systems: PCC is used to create drainage channels and other structures that help control the flow of water in residential and commercial areas.
• Plain cement concrete in Flooring: PCC can be used as a flooring material in residential and commercial buildings, providing a strong and durable surface that can be finished with various materials for aesthetic appeal.

Characteristics of Plain Cement Concrete

• Compressive strength: 200 to 500 kg/sq. cm
• Tensile strength: 50 to 100 kg/sq. cm
• Density: 2200 to 2500 kg/sq. cm (135 to 155 lb/ft³).

What are the components of plain cement concrete?

The materials or ingredients used to form plain cement concrete are as follows:

• Cement
• Fine aggregate (sand)
• Coarse aggregate (stone chips)
• Water

Cement
The cement used for plain cement concrete is Portland pozzolana cement (PPC). The cement should conform to the standard specifications like fineness, strength, setting time, etc.

Fine aggregate (sand)
The sand used for PCC concrete should be :

• Free from dust and organic materials
• Hard, angular, and sharp
• Because of weak binding ability, the sea sands are to be avoided
• Free-form surface moisture
• Free from any harmful impurities such as iron, salt, coal, etc.
• Silt content should be less than 3% by weight (less than 12% by volume in about 10 minutes)
• The Fineness modulus should be 1.2-1.5.

Coarse aggregate (stone chips)
The coarse aggregate used for PCC concrete should be :

• free from dust, dirt, and other organic materials
• hard broken stones like granite, basalt
• The maximum size of coarse aggregate shall be 20 mm or less.
• So well graded that the voids shall not be more than 42%

Water
The water used for mixing PCC concrete should be –

• clean and free from any injurious materials like oil, acids alkalies, salts, and decayed vegetables.
• The water which is suitable for drinking is also good for PCC in construction.
• The percentage of organic solids should not exceed 0.02%
• The percentage of inorganic solids should not exceed 0.30%
• The percentage of sulfates should not exceed 0.05%
• The percentage of alkali chlorides should not exceed 0.10%

Preparation of Plain Cement Concrete

The preparation of PCC work in construction involves the following steps:

• Proportioning of concrete
• Mixing the ingredients
• Transportation of concrete
• Placing of concrete
• Compaction of concrete
• Finishing.
• Curing of concrete.
• Removal of Form-work.

Proportioning of PCC
There are various methods of proportioning concrete mixtures for PCC work. These methods are as follows:

1. Arbitrary standard method
2. Minimum voids method
3. Maximum density method
4. Fineness modulus method
5. Water-cement law

Mixing the ingredients
The mixing methods followed when mixing the ingredients are:

• Hand mixing method
• Machine mixing method

Transportation of PCC

• The concrete has to be transported to the place of casting before the hydration of cement starts.
• When the concrete is to be transported to a higher level continuously, belt conveyors should be used.
• A truck mixer must be used when the mixing site is far away from the worksite.
• When the mixing site is near the worksite, a pan or wheelbarrow must be used for transportation.

Placing of Plain cement concrete

• The concrete should be placed before the start of its initial setting.
• The method of placing concrete should prevent segregation.
• The formwork should be checked thoroughly before placing the concrete.
• During rain, the concrete should not be placed.
• Walking on freshly placed concrete should be avoided.
• Concrete should be laid on a regular level surface without any loose matter spread on it.

Compaction of concrete
The consolidation of plastic concrete is known as compaction. The object of this method is to reduce the voids in compacted concrete. Compaction of concrete is generally done in two methods:

• Hand compaction
• Machine compaction

Finishing
Finishing is providing desired smoothness to the surface of the compacted concrete. The slump of the concrete should not be more than 5cm for providing a good surface finish. Screeding, floating, and trowelling are the operation for finishing a concrete surface.

Curing of concrete
The operation in which moist conditions are maintained on finished concrete surfaces for promoting the continuous hydration of cement is termed as curing of concrete. Without proper curing, the concrete will not gain its full strength and shrinkage cracks will develop. There are various methods of curing concrete.

• Ponding
• Membrane curing
• Sprinkling water
• Covering with wet gunny bags

Removal of Form-work
The hardening of concrete depends on the atmospheric temperature and the removal of formwork depends on the hardening of concrete

Prequation for PCC in construction:

There are some important points to be remembered while doing PCC in civil construction.

• The shuttering work has to be perfect in size and shape in PCC work.
• The amount of water should be added as per the specification ( water-cement ratio).
• De-watering must be performed at the time of concreting if the water table is high.
• The concrete mixture should never be placed bare-handed.

Mixing and Proportions of PCC

Mixing Process

The mixing of PCC involves thorough blending of the cement, aggregates, and water to achieve a homogeneous mixture. This can be accomplished manually or by using mechanical mixers, ensuring the ingredients are evenly distributed.

Proportions of Ingredients

The proportions of cement, fine aggregate, coarse aggregate, and water vary depending on the intended application and design requirements. Generally, the mix is designed to achieve a certain compressive strength, with common ratios ranging from 1:2:4 to 1:4:8 (cement:sand:aggregate by volume).

Necessity of Laying Plain Cement Concrete

The PCC layer acts as a protective barrier between the ground surface and the RCC works to protect the reinforcement from touching the ground. On the PCC layer, cover blocks are placed. These cover blocks are used to maintain the covers for the reinforcement.

Advantages and Disadvantages of plain cement concrete

Advantages Of Plain Cement Concrete:

Strength and durability: PCC has good compressive strength and it is able to withstand heavy loads. It is suitable for structural elements such as foundations, columns, and beams. It is also very durable and its life span is very long.

Low cost: Plain Cement Concrete is an economical construction material. It is generally made from readily available materials such as cement, aggregates, and water.

Easy to mix and place: Plain Cement Concrete can be easily mixed and placed, Which makes it a popular choice for construction activities such as foundations, footings, and floor slabs.

Versatility: Plain Cement Concrete can be used for various construction applications, from structural elements to finishing materials such as floors and pavements.

Disadvantages of Plain cement Concrete:

Low tensile strength: PCC has low tensile strength, which means it can crack and fail under tension. This can be addressed by reinforcing it with steel bars, but this can increase the cost of construction.

Brittle: PCC is a brittle material, which means it can crack easily under impact or sudden loads.

Prone to shrinkage and cracking: PCC can shrink and crack as it dries, which can cause damage to the structure and affect its stability.

Susceptible to weathering: Plain cement Concrete can be affected by weathering and it can deteriorate over time, especially in areas with extreme weather conditions. This is why proper maintenance is required to ensure its longevity.

Plain cement concrete Indian Standards

In India, the Bureau of Indian Standards (BIS) has established the following standards for PCC:

• IS 456:2000 – Plain and Reinforced Concrete – Code of Practice: This code provides guidelines for the design, construction, and quality control of PCC structures. It covers aspects such as mix proportioning, mixing and placing of concrete, curing, and testing of fresh and hardened concrete.
• IS 10262:2009 – Guidelines for Concrete Mix Design Proportioning: This standard provides guidelines for the selection of mix proportions for PCC, based on the desired strength and durability requirements.
• IS 383:2016 – Specification for Coarse and Fine Aggregates from Natural Sources for Concrete: This standard specifies the requirements for the quality of coarse and fine aggregates used in PCC. It covers aspects such as grading, strength, and durability.
• IS 2386 – Methods of Test for Aggregates for Concrete: This standard provides guidelines for the testing of aggregates used in PCC, including tests for grading, strength, and durability.
• IS 516:1959 – Methods of Tests for Strength of Concrete: This standard provides guidelines for the testing of the compressive strength of PCC. It covers aspects such as the preparation of test specimens, the method of testing, and the interpretation of test results.

Plain cement concrete International Standards

There are several global standards have been established to ensure the quality and durability of PCC. Some of those global standards for PCC are as follows:

• ASTM C94/C94M – Standard Specification for Ready-Mixed Concrete: This standard covers the requirements for ready-mixed PCC that is delivered to a construction site. It includes specifications for materials, mix proportions, testing, and quality control.
• ASTM C150 – Standard Specification for Portland Cement: This standard covers the requirements for Portland cement, which is a key ingredient in PCC. It includes specifications for chemical composition, physical properties, and performance characteristics.
• BS EN 206-1 – Concrete Specification, Performance, Production, and Conformity: This European standard provides guidelines for the design, production, testing, and performance of PCC. It covers aspects such as mix design, workability, durability, and strength.
• ACI 318 – Building Code Requirements for Structural Concrete: This American Concrete Institute (ACI) standard provides guidelines for the design and construction of PCC structures. It covers aspects such as mix design, structural requirements, durability, and testing.
• ISO 22965-1 – Concrete – Part 1: Specification, performance, production, and conformity: This international standard provides guidelines for the production, testing, and performance of PCC. It covers aspects such as mix design, workability, strength, and durability.

PCC vs. Reinforced Cement Concrete (RCC)

PCC and RCC differ primarily in the presence of reinforcement. While PCC does not contain any reinforcement, RCC utilizes steel bars to enhance its tensile strength. RCC is commonly used in structural elements requiring higher load-bearing capacities, such as columns and beams.

Construction Applications of PCC

Foundations

PCC serves as the primary material for constructing foundations. It provides a stable and level base for the load-bearing walls, ensuring the overall structural integrity of buildings.

Pavements and Walkways

PCC is extensively used in the construction of pavements and walkways due to its durability and ability to withstand heavy traffic. It provides a smooth and robust surface for pedestrians and vehicles.

Flooring

PCC acts as a reliable flooring material, especially in industrial and commercial settings. It offers a sturdy and level surface that can be further finished with tiles, epoxy coatings, or other decorative options.

Dos and Don’ts of PCC Works

When working with plain cement concrete (PCC), it is essential to follow certain dos and don’ts to ensure the quality and longevity of the construction. By adhering to these guidelines, you can maximize the benefits of PCC and avoid common pitfalls. Let’s explore the dos and don’ts of PCC works.

Dos:

1. Do ensure proper site preparation: Before pouring PCC, prepare the site by clearing debris, compacting the soil, and providing a stable base for the concrete.
2. Do use quality materials: Use high-quality cement, aggregates, and water to ensure the strength and durability of the PCC. Adhere to recommended standards and specifications.
3. Do follow the right mixing process: Thoroughly mix the cement, aggregates, and water using the appropriate mixing equipment. Achieve a uniform consistency and ensure all ingredients are evenly distributed.
4. Do pay attention to proportions: Follow the recommended proportions of cement, sand, and aggregate as per the design specifications. Accurate proportions ensure the desired strength and workability of the PCC.
5. Do provide proper curing: Curing is crucial for the development of strength in PCC. Maintain the required moisture and temperature conditions for the specified curing period to enhance the durability of the concrete.
6. Do protect the fresh concrete: Protect the freshly poured PCC from excessive sunlight, wind, and rapid drying to prevent shrinkage cracks. Use wet coverings or curing compounds to retain moisture during the initial curing stages.
7. Do joint the concrete: Provide expansion and contraction joints in large PCC surfaces to accommodate shrinkage and thermal movements. Proper jointing helps minimize crack formation and ensures the structural integrity of the concrete.

Don’ts:

1. Don’t add excess water: Avoid adding excess water to the PCC mixture. It can weaken the concrete, negatively impacting its strength and durability. Maintain the recommended water-cement ratio for optimal results.
2. Don’t neglect proper compaction: Adequate compaction is essential to eliminate air voids and ensure proper bonding between the aggregates. Neglecting compaction can lead to weak spots and reduced strength.
3. Don’t rush the finishing process: Take time to properly finish the PCC surface. Rushing the finishing process can result in an uneven or weak surface prone to cracking and deterioration.
4. Don’t overload the fresh concrete: Avoid placing heavy equipment or loads on the fresh PCC. Excessive loads can cause structural damage and compromise the integrity of the concrete.
5. Don’t forget to cure the concrete: Neglecting proper curing can result in reduced strength, increased porosity, and susceptibility to cracking. Ensure consistent and adequate curing throughout the curing period.
6. Don’t ignore maintenance: Regularly inspect and maintain PCC structures. Address any signs of deterioration promptly, such as cracks or spalling, and take appropriate measures to prevent further damage.

Conclusion

Plain cement concrete plays a vital role in the construction industry, serving as the foundation for various structures. Its simplicity, durability, and cost-effectiveness make it a preferred choice for foundations, pavements, and flooring.

While PCC has its limitations, proper mixing, curing, and maintenance can mitigate these concerns. By understanding the components and applications of PCC, construction professionals can harness its potential to build solid and enduring structures.

FAQs on Plain cement concrete

What is the full form of PCC in civil engineering?

PCC in construction stands for Plain Cement Concrete.

Where is PCC used in construction?

PCC is in general found in footings, grade slabs, and concrete roads. It is provided when the underlying soil is weak and flexible.

What is the density of plain cement concrete?

The density of Plain Cement Concrete (PCC) depends on its composition, specifically the ratio of cement, sand, and aggregate used.
In General, the density of Plain Cement Concrete ranges from 2200 to 2500 kg/m³.
The actual density of Plain Cement Concrete (PCC) depends on the specific materials used, the degree of compaction, and other factors.

What is the size of aggregate used in plain cement concrete?

In Plain cement concrete, the size of fine aggregates ranges from 0.075 to 4.75 mm (No. 200 sieve to 3/16 inch) and the size of coarse aggregates ranges from 4.75 to 80 mm (3/16 inch to 3 inches).
The maximum size of the coarse aggregates should not exceed 1/3 of the thickness of the concrete section, or 75% of the minimum dimension of the formwork, whichever is smaller.

What is the compressive strength of plain cement concrete?

The minimum compressive strength for M15 is 10 MPa (1450 psi) and for M25 grade PCC is 20 MPa (2900 psi).

What are the plain cement concrete grades?

The most commonly used plain cement concrete grades & mix ratios are:

M5 – 1:5:10 (cement: sand: aggregates)
M7.5 – 1:4:8
M10 – 1:3:6
M15 – 1:2:4
M20 – 1:1.5:3
M25 – 1:1:2
M30 – 1:0.75:1.5
M35 – 1:0.5:1
M40 – 1:0.25:0.5

What is Lean Concrete?

This is a type of PCC has a low cement content and is used as a base layer for pavements and as a backfill material.

Do we provide reinforcements in plain cement concrete?

Plain Cement Concrete (PCC) does not contain any reinforcement, and it is not designed to resist any significant tensile stresses.