What Is Hardened Concrete?
Hardened concrete is a type of concrete that is strong and have the capacity to bear the structural as well as service loads that are applied to it. Hardened concrete is one of the strongest and durable construction materials.
Hardened concrete is concrete that is completely set and able to take the loads. In this article, we will go through the properties of Hardened concrete.
Properties of Hardened Concrete
There are various properties of hardened concrete which are as follows.
1. Strength of Harden Concrete
The strength of the concrete plays a vital role in the construction of any building. The strength of the concrete helps to identify whether the concrete can be used in construction or not.
The strength of the concrete is defined as the maximum amount of load which the concrete can bear. Strength is considered as one of the most important and valuable properties of concrete.
The strength of the concrete gives the overall idea of quality of the concrete and the materials used in the manufacturing of the concrete. The concrete is tested for three types of strength which are compressive strength, tensile strength, and flexural strength.
When we talk about the strength of the concrete we are generally considered compressive strength, because we know that concrete is strong in compression and weak in tension. The concrete is mainly used for its compressive strength.
Flexural strength of the concrete is defined as the measure of an under-reinforced concrete beam or slab to resist failure in bending.
Factors Affecting the Strength of the Concrete
Following are the factors which affect the strength of the concrete.
1.1. Type of aggregates
Aggregates are the essential component part of the concrete. It will give volume to the concrete. The aggregates which are used in the manufacturing of the concrete should have high compressive strength so that it will produce concrete with good strength.
The aggregate which has sharp edges and rough texture will develop a strong bond between cement. Aggregates with a smooth texture and rounded shape result in a weaker bond between cement and aggregate.
1.2. Water cement ratio
The strength of the concrete depends upon the water-cement ratio used during the manufacturing of the concrete. The compressive strength of the concrete decreases with an increase in the water-cement ratio.
The optimum water content should be used to ensure the complete hydration of the cement.
1.3. Type of Cement
Cement is a binding material that is used to bind sand and aggregates with each other to form hardened concrete. Finer the size of the particles of the cement more will be the ultimate compressive strength.
The cement which has a higher composition of tricalcium silicate will develop concrete with higher strength.
1.4. Types of Admixture used
Admixtures are added to the concrete to achieve the desired property of the concrete. Admixtures in the concrete helps to improve the compressive strength.
1.5. Weather conditions
The weather conditions are also one of the factors which affect the compressive strength of the concrete. The concrete which is casted in the hot climate and the concrete which is casted in the cold climate has different values of compressive strength.
1.6. Curing conditions
It is very necessary that proper and adequate curing should be done to obtain maximum compressive strength of the concrete. Incomplete curing can cause a loss in the compressive strength of the concrete.
1.7. Method of Preparation
The method which is used in the preparation of the concrete also plays a vital role which also affects the overall strength of the concrete.
So that it is very necessary that skilled worker should work during the manufacturing of concrete otherwise we cannot achieve the desired strength in spite of using cement and aggregates in the concrete.
2. Impermeability of Harden Concrete
Impermeability is the one of the properties of hardened concrete which resists the flow of water through its pore. Permeability directly affects the durability of the concrete so it is very necessary that the concrete should be less permeable.
Excess of water-cement ratio may develop pores or cavities in the concrete which makes the concrete permeable.
3. Durability of Harden Concrete
Durability is also an important factor that affects the quality of the Hardened concrete. The durability of the concrete can be defined as the capacity of the concrete to bear all the forces of the deterioration.
Durability is also known as the period of existence of the concrete without getting adversely affected by Aggressive environmental conditions. There are various causes that affect the durability of the hardened concrete which are Frost action, chemical reaction, alkali-aggregate reaction.
Frost action causes the deterioration of the concrete in cold climates. The reason of frost action is due to the freezing of water within the concrete pores in the extremely comfortable cold climate.
Concrete is liable to attack various acids and to attack various acids and salts which can destroy the concrete structure.
4. Dimensional Changes of Harden Concrete
Dimensional stability is also one of the properties of hardened concrete. The dimensional stability of the concrete is nothing but the behavior of the concrete under various forces.
Concrete is not a completely elastic material or completely plastic material. When the hardened concrete is loaded it undergoes deformation.
Permanent dimensional change in the hardened concrete is due to loading for a longer period which is generally known as Creep. Its value mainly depends upon the stress and the age of the concrete at the time of the loading.
5. Shrinkage of Harden Concrete
There are three types of shrinkage through which hardened concrete undergoes and which are important as per as its dimensional stability is concerned.
- Plastic shrinkage
- Drying shrinkage
- Thermal shrinkage
5.1. Plastic Shrinkage
Plastic shrinkage is a type of shrinkage in which the freshly placed concrete on the construction site undergoes till it sets completely.
This type of shrinkage is also commonly known as the initial Shrinkage and the excessive shrinkage in the concrete at its initial stage may affect the strength of the concrete.
The rate of plastic shrinkage mainly depends upon the rate of evaporation of water and the temperature during the casting of the concrete. The plastic shrinkage of the concrete is higher if the cement content in the concrete is more.
5.2. Drying Shrinkage
Drying shrinkage is a type of shrinkage which occurs after the concrete has completely set and hardens. There are some volume changes after setting of the cement which is because of the contraction of the gel structure.
The main cause of the drying shrinkage is the loss of the water content because of the evaporation from the freshly hardened concrete which is exposed to the environment.
5.3. Thermal Shrinkage
Thermal shrinkage is a type of shrinkage which occurs due to falling in the temperature of the concrete from the time it is placed upto it sets completely.
Frequently Asked Questions (FAQs) About Hardened Concrete:
What is hardened concrete?
Hardened concrete refers to concrete that has fully set and hardened, capable of bearing structural loads.
What are the properties of hardened concrete?
Hardened concrete exhibits properties such as strength (compressive, tensile, flexural), impermeability, durability against environmental factors, and dimensional stability.
What factors influence the strength of hardened concrete?
Factors affecting concrete strength include the type of aggregates used, water-cement ratio, type of cement, admixtures, curing conditions, weather during casting, and the method of preparation.
How does impermeability affect hardened concrete?
Impermeability in concrete refers to its ability to resist water penetration, which directly impacts its durability. Lower permeability reduces the risk of deterioration due to moisture.
What is the significance of durability in hardened concrete?
Durability in concrete refers to its ability to withstand various environmental stresses over time, including frost action, chemical reactions, and alkali-aggregate reactions.
What are the dimensional changes and shrinkage in hardened concrete?
Dimensional changes in concrete include creep (long-term deformation under sustained load) and shrinkage (plastic, drying, and thermal), which affect its overall stability and performance.
How can hardened concrete be optimized for strength and longevity?
Optimizing concrete involves selecting appropriate materials, controlling the water-cement ratio, ensuring proper curing, and considering environmental conditions during placement.
What are common challenges in maintaining hardened concrete structures?
Challenges include controlling cracking due to shrinkage, preventing deterioration from environmental exposure, and ensuring structural integrity over the lifespan of the concrete.
How does testing ensure the quality of hardened concrete?
Testing methods such as compressive strength tests, permeability tests, and durability assessments help evaluate the quality and performance of hardened concrete in various applications.
What are some sustainable practices in concrete construction?
Sustainable practices include using recycled materials in concrete production, optimizing mix designs for durability, and adopting efficient construction techniques to reduce environmental impact.
