We are using many types of cement to make an excellent concrete which withstands any possible failure situation by the types of loads acting on the structure.
But it’s not a single thing that assists the concrete to make it great. There are a set of properties…
Here we are going to discuss the same.
- What is Concrete?
- Properties of Fresh Concrete
- Properties of Hardened Concrete
What is Concrete?
Concrete is a blended material of cement, sand, water, and coarse aggregate or lightweight material.
- Where coarse aggregate act as building blocks of the concrete
- Fine aggregate act as filler material to remove air entraining into the concrete and reduce the shrinkage of concrete
- Cement act as glue to mix fine and coarse aggregate to make it harden form
- The concrete will become a hardened element when the above components react with water.
Advantages of concrete
- Concrete has high compressive strength.
- Corrosion and weathering effects are minimal.
- Economical and little maintenance, if required.
Disadvantages of concrete
- Concrete is strong in compression and weak in tension, so the steel reinforcement required.
- Contraction joints or Expansion joints must be provided in the concrete to avoid the development of the cracks due to the shrinkage or moisture.
- Concrete is disintegrated by alkali and sulphate attack.
Properties of Concrete
Concrete will have a different set of properties on its semi-liquid and hardened form. Both properties will impact the end result. So let’s discuss both.
Properties of Fresh Concrete ensures that the concrete is
- Ease of workability
- Has less bleeding
- Has less segregation
- Has less Harshness
Properties of Fresh Concrete
1. Workability of Concrete
The ability to handle and place the concrete and compact without segregation and bleeding is called the workability of concrete. The workability of concrete depends on the quality of material, proper mixing, and water-cement ratio. We can measure the workability of concrete by the Slump Test.
2. Bleeding of Concrete
Water surfacing on the freshly laid concrete when compacting is known as concrete bleeding. The concrete bleeding happens due to the excessive compaction or too much water-cement ratio in the concrete mix.
It creates the pores in the concrete and makes it weak. The quality of material, water-cement ratio, and proper compaction will avoid the bleeding.
3. Segregation of Concrete
The separation of aggregates from the fresh concrete, which results in non-uniformity, is called segregation. Due to the segregation activity, concrete honeycombs may form and decrease the strength of the concrete.
4. Harshness of Concrete
When the finished concrete surface is not smooth even after trying with a hand trowel is known as the harshness of concrete. This is the result of improper grading and less cement mortar mix. We have to ensure to use proper mix ratio
Properties of Hardened Concrete
Properties of hardened concrete ensure the
- Strength of concrete
- Durability of structure
- Shrinkage of concrete
- Creep of Concrete
- Thermal Expansion
- Changes in Dimension
1. Strength of Concrete
I hope this is the only test that most of us would remember studying in college.
The strength of concrete is nothing but the concrete’s resistance capacity to bear the compression load after it has hardened. The strength of concrete will gradually increase from day one and attains its max strength on day 28.
|Days||Percentage of Strength|
The grade of concrete and other properties will impact the characteristic strength of hardened concrete. The concrete strength is measured by the compressive & tensile test.
The compressive strength of concrete depends on the following factor
- Types of Cement
- Water Cement Ratio
- The shape of the cube
- Quality of materials
- Grade of cement
Generally, the tensile strength of concrete will be 10 to 12 % of its compressive strength.
2. Durability of Concrete
The durability of concrete is the resistance capacity against environmental conditions like weathering, chemical attack, and corrosion. Usually, the concrete has high durability. But sometimes the steel may corrode if the concrete is porous and makes way to concrete crazing.
It is better to ensure that we are using a proper mix and sufficient compaction to enhance durability.
3. Shrinkage of Concrete
The shrinkage of concrete depends upon the components, such as the size of the member and weathering conditions also because of the delayed curing. The approx value of the shrinkage strain is 0.0003 as per the IS code 1343.
We have discussed this topic (Shrinkage of Concrete) in detail.
4. Creep of Concrete
The inelastic deformation of concrete while applying the compression load is called a creep of concrete. The Stress in concrete should not exceed 1/3rd of its compressive strength.
|Age at Loading||Creep Co-efficient|
5. Change in Dimension
The dimensional changes in concrete may happen due to the shrinkage, plasticity, and creep of concrete. The dimensional changes may lead to the formation of the crack.
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