Concrete Ingredients – Important Properties and Tests

What is Concrete?

Concrete is the largest consumed human-made heterogeneous material. Ordinary concrete made by mixing cement(inorganic material), water, natural sand or stone dust, natural stone and admixture. The aim is to combine these Concrete Ingredients as per designed ratio to make concrete easy to transport, place, compact and finish and which will set, and harden, to give a durable and robust product.

Also, Read: Properties of Concrete – Introduction to Good Concrete Practice

Advantages and Disadvantages of Concrete Mix:

Advantages of Concrete Mix:

• Ingredients are readily available.
• Low life-cycle cost
• Can easily be handled and moulded to any desired shape
• Robustness
• Can be designed for selected properties
• Due to the monolithic character of concrete, it gives a better appearance and much rigidity to the structure

Also, Read: Design Mix of Concrete – Detailed Procedure With Calculation

Disadvantages of Concrete Mix:

• Low tensile strength
• Low ductility
• Demands strict quality control

Concrete Ingredients:

Cement:

It is necessary to use cement as concrete ingredients of appropriate grade and type for specific applications and environmental conditions. The following varieties of cement for concrete are used for Bridge/Structure construction work.

Also, Read: Rusting of Iron Rebar in Concrete – Special Repairing

Also, Read: Blowholes/Surface voids/Bugholes in Concrete Surface

Physical Characteristics of Various Types of Cement as per IS:

Also, Read: Causes, Prevention and Repair of Concrete Surface Defects

Deliberations needed by BIS:

• Considering the hot weather conditions in India, it is necessary to insist on a higher initial setting time for cement, e.g. about 60 minutes.
• Chloride content: It is an essential requirement from durability consideration.
• Manufacturers produce major Concrete Ingredients cement with increased fineness to improve compressive strength. Not desirable in hot weather concreting. The upper limit of around 280 should be specified.
• The heat of Hydration: No limit specified in IS. for hot weather concreting it should be (i) 7 days < 270 Kj/Kg and (ii) 28 days < 320Kj/Kg. For cold weather, it should be more.

Storing of Cement at Site:

• Cement store godown should be dry, leak-proof and as moisture-proof as possible
• cement bags should be stack on wooden platform 150-200mm above the floor top of cement storage godown.
• The floor may include lean cement concrete or two layers of bricks laid over well-compacted earth.
• Storing of cement shall be done in such a way that The height of each cement bag stacked should not be more than ten bags of cement.
• Cement bags should be stack close to each other.
• The height of each cement bag stacked should not be more than ten bags of cement.
• The width of the stack should not be more than four cement bags
• Bags should be placed alternately length-wise and cross-wise
• Stack to facilitate use in the order in which they arrived.
• Put label showing date of receipt of on each bag
• Enclose the stack by a waterproofing membrane/tarpaulin
• Stack different types of cement separately in the godown.

Also, Read: Nondestructive Testing of Concrete – Methods & Guidelines

Coarse and Fine Aggregate:

Most important concrete ingredients aggregates play an essential role to establish the properties of concrete such as water-cement ratio, cohesiveness and workability of concrete in plastic stage, while they affect compressive strength, density, durability, permeability in the hardened stage. The following tests are conducted to determine the quality of aggregate for concrete:

Also, Read: Determination of Sieve Analysis For Fine Aggregate

Also, Read: Sieve Analysis of Coarse Aggregate Test – Construction Civil

• Gradation
• Estimation of deleterious materials and organic impurities
• Combined Flakiness and Elongation Index
• Aggregate Crushing Value
• Aggregate Abrasion Value
• Soundness of Aggregate
• Alkali Aggregate Reactivity

Water:

The following tests are conducted to determine the quality of water for concrete mix:

• pH value
• Limits of acidity
• Limits of alkalinity
• %age of solids
• Chlorides
• Suspended matters
• Sulphates
• Inorganic solid

Also, Read: Factors Affecting Strength of Concrete – Construction Civil

Admixtures:

Chemical Admixture for Concrete: 

Used as specific property/performance enhancer. Chemical admixture can be classified by function as under:

• Water reducing admixture
• Plasticizer for high slump or flowing concrete
• Accelerating admixture
• Retarding admixture
• Shrinkage reducer
• Corrosion inhibitor
• Air-entraining admixture
• Foaming agent

Mineral Admixture for Concrete: 

Mineral admixtures are used as concrete ingredients for the improvement of long term strength and durability performance. Mineral admixture include

• Fly ash
• Silica fumes
• Ground granulated blast furnace slag
• Rice husk ash

By using the above two types of admixtures together, high strength and high-performance concrete may be designed.

Also, Read: Formula for Development Length, Anchorage and Lapping Length

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Article Name

Concrete Ingredients - Important Properties and Tests

Description

Combining concrete ingredients as per designed ratio to make concrete easy to transport, place, compact and finish and which will get set and harden.

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WhiteHelmet

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Construction Civil

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