Question

1. Creep is one of deformation that occurred in concrete structure. Give one example that can be associated with creep problem in concrete structure. Define what is creep and discuss on how the creep occurred in choosen example.

2. Moisture movement in concrete is one of the factor that influencing shrinkage and creep. Elaborate this effect and how to differentiate between these properties.

3. With coastal and offshore concrete structures directly exposed to seawater, why does most of the deterioration occur in the tidal zone? From the surface to the interior of concrete, what is the typical pattern of chemical attack in sea structures? Discuss the mechanism for the chemical attack in the structures.

4. Concrete has been used since ages. In your opinon, how is relavant the advanced knowledge in concreting for the construction industries.

Answer 1

1. Creep is a time dependent long-term inelastic deformation due to dead or sustained load. Creep occurs in concrete due to moisture present in the concrete. if sustained longterm load is applied on concrete, it will cause movement of moisture in concrete, which ultimately lead to creep in concrete. So C-S-H hardened gel is prime reason for creeping in concrete.

2. As we all know that shrinkage is volume reduction of concrete due to loss of moisture in the form of evaporation but creep is long term deformation due to sustained load. Initially moisture loss is due to evaporation so it will cause immediate shrinkage in concrete but as time passes if there is a sustained load on concrete this will cause movement of this moisture which is present in the concrete on C-S-H hardened concrete. Shrinkage is immediate effect but creep is long-term effect.

3. In seashore or tidal region concrete structure easily get deteriorated, as it is caused by chlorides and sulphates present in the moisture in costal and tidal region. chlorides is worst in all present salts. These chloride and sulphate accelerate the process of corrosion in presence of moisture and oxygen. As minor cracks present in concrete helps in the process of rusting. So when rusting occurs in concrete it will cause sudden increase in volume of concrete which is called spalling of concrete, which ultimately cause damage to the whole structure.

4.Concrete is one of the most important invention of the 19th century. Concrete made possible many most important structures in the world. Its one of the important property is it can moulded in any shape easily. Concrete along with steel help in Earthquake resistance. Hence it can be used in industrial buildings and frames.