Why Maintenance Of RCC Structures are Necessary
Reinforced cement concrete (RCC) have come to be used as build materials in the last one century. In India it is been used for 50–60 years. RCC are usually used to build large structure as concrete in itself lacks the tensile strength and ductility required to support such structures. Steel bars are usually not necessarily used for reinforcement. With the invention of RCC modern humans have built large infrastructures like multi-storeyed buildings, sports stadiums, bridges, shopping malls and many more. It wouldn’t have been possible to build the modern structures that we have built today without reinforced cement concrete. One of the greatest example being the Burj Khalifa — the tallest building in the world. It stands at 829.8 metres. Construction of such a massive structure would never have been possible without RCC.
These large structures have been created with huge investment and it cannot be affordable to be created over again out of limited national resources. Therefore, it is very much needed to be maintained and repaired whenever needed, deterioration of RCC is quite natural which is clearly visible in a large number of structures. The structure need to be evaluated close in order to identify the causes of deterioration for consequent repair and rehabilitation of structures. Causes of deterioration needs to be properly identified and taken care of constantly. If they remain unattended for too long a time, then many factors will affect the integrity of the building viz. fungus growth, water leakage, cracks and many more. Moisture may reach the steel bars and cause corrosion and further damage the outer cover of concrete. Practicing civil engineers do not usually realize the need for maintenance, repair and rehabilitation of structures. ‘Code of Practice on Plain and Reinforced Concrete’ has been revised in order to give emphasis on the durability provisions. Even internationally, attention is being drawn towards structural rehabilitation.
Structural rehabilitation is not just required for modern day structures. It is needed for heritage sites as well. Repair and rehabilitation of heritage structure have become very important around the world as people are realising the need of preserving heritage sites. As these structures are subjected to natural deterioration they become unable to fulfil the purpose they were created for. So their repair and rehabilitation is very much needed. Sometimes heritage structures are needed to be preserved to be showcased as a counterpoint of architectural development over time. The cultural value associated with the structure plays a major role while deciding the level of intervention on the structure i.e. simple maintenance so that the cultural value is not affected and complex structural rehabilitation so as to increase the performance of the building.
One of the most important technique used in structural rehabilitation is gunite and shortcrete. It is a mix of cement, coarse aggregates, sand and water carried through hose and applied onto the surface with high velocity. They are reinforced with steel mesh.
· Dry mix — it is cement and aggregates mixed with just enough water in order to avoid dusting
· Wet mix — it is same as dry mix just with more water to make concrete which is pumped through hose.