Do you need to remove the ads? Join now!
Join TheConstructor to ask questions, answer questions, write articles, and connect with other people. When you join you get additional benefits.
Log in to TheConstructor to ask questions, answer people’s questions, write articles & connect with other people. When you join you get additional benefits.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Why does modulus of elasticity of concrete reduce with time?
CB Sowmya
The Modulus of Elasticity reduces with time because of the effect of creep. Creep is the phenomenon that occurs in hardened concrete over time, where for constant load or stress, deformation increases. Keeping that in mind, let us look at the definition of modulus of elasticity of concrete. It is thRead more
The Modulus of Elasticity reduces with time because of the effect of creep. Creep is the phenomenon that occurs in hardened concrete over time, where for constant load or stress, deformation increases.
Keeping that in mind, let us look at the definition of modulus of elasticity of concrete. It is the slope of the initial tangent modulus of the stress-strain curve of concrete.
The above graph shows the stress-strain curve of the concrete at an early stage.
Due to creep, for a given load/stress, deformation increases, thereby strain increases. This has been explained in the following graph.
As a result, the slope of the curve reduces and becomes like this.
As the curve descends, the slope of the initial tangent modulus of the stress-strain curve of concrete reduces.
As a result, the modulus of elasticity also reduces.
Thank you!
See lessWhy strength of white cement is less than OPC cement?
CB Sowmya
The process of manufacturing white cement is different from that of the OPC. To achieve the white color, limestone, chalk, and clay are the primary materials, and they cause the cement to expand. This expansion leads to lower strength. However, this shortcoming has been overcome by many cement manufRead more
The process of manufacturing white cement is different from that of the OPC. To achieve the white color, limestone, chalk, and clay are the primary materials, and they cause the cement to expand. This expansion leads to lower strength.
However, this shortcoming has been overcome by many cement manufacturers, and now the white cements have equal strength to that of the OPC cement.
See lessWhat is the percentage of fineness content in OPC for construction works?
CB Sowmya
As per IS code provisions, the fineness of cement is calculated by sieving 100 grams of the cement sample in a 90-micron sieve. The weight s the cement-retained on the sieve is taken. Fineness of cement = Percentage retained = (Weight retained / weight taken) x 100 A good cement should have the percRead more
As per IS code provisions, the fineness of cement is calculated by sieving 100 grams of the cement sample in a 90-micron sieve. The weight s the cement-retained on the sieve is taken.
Fineness of cement = Percentage retained = (Weight retained / weight taken) x 100
A good cement should have the percentage retained not more than 10%.
The same is applicable to OPC as well.
See lessWhat is effect of steel and aluminium, if we use it as reinforcement in structure?
CB Sowmya
The main reason why we don't use aluminum in reinforced concrete structure is because of its property of coefficient of thermal expansion. The co efficient of thermal expansion for various materials are as follows Concrete - 14.5 Steel - 12 Aluminum - 22.5 Higher the Co efficient of thermal expansioRead more
The main reason why we don’t use aluminum in reinforced concrete structure is because of its property of coefficient of thermal expansion.
The co efficient of thermal expansion for various materials are as follows
Higher the Co efficient of thermal expansion, faster will the corresponding material expand to a given temperature. Therefore, for safety reasons, a reinforcing material of concrete should have the co efficient of thermal expansion nearer to that of concrete (14.5 for concrete).
Aluminum has a high coefficient of thermal expansion of nearly 22.5. So if aluminum is used, then the reinforcements would expand first while the concrete is still intact. This causes unnecessary stresses and lead to the failure of the structure.
Therefore we only use steel for reinforcements as its coefficient of thermal expansion is in the vicinity of that of the concrete.
See lessWhat is fatigue in any structural member?
CB Sowmya
The reduction in strength of a member due to cyclic loading is called fatigue. However, the fatigue reaches a constant point over a time. This point is called the endurance limit. The reduction in strength of the member, i.e., fatigue, cannot go beyond a certain value. That value is called as the ENRead more
The reduction in strength of a member due to cyclic loading is called fatigue. However, the fatigue reaches a constant point over a time. This point is called the endurance limit. The reduction in strength of the member, i.e., fatigue, cannot go beyond a certain value. That value is called as the ENDURANCE LIMIT and it is explained in this graph. The endurance limit mostly happens after 2 million loading cycles.
Thank you!
See less