Evolution of RCC - Steel Reinforced Concrete

Thursday, 28 October 2021 09:58

Since the beginning of the human civilization, shelter had been of prime importance as a basic need. Human being looked for primitive to modern shelters for its safety, security and need for rest after daylong struggle for existence. And thereafter gradually, with the improvement in the quality of lives, geography, availability of local materials, the shelter evolved from tree branches, cave and mud/stone houses to modern age residences – log bridges evolved to massive modern bridges and many more. 

In the earlier days all constructions were wholly masonry based, uses of thick walls, massive columns, buttresses and arches were the prime building methods or components. These were basically to mitigate the deficiencies of masonry structures against tensile/bending forces. During those historic days most of the masonry construction was sponsored by financially elevated class like Emperors, Kings and landlords of various stature. But desire for residing in “PUCCA” building / shelter remained as an universal desire for all human being, irrespective of their financial stratification in the social pyramid.

With increased need and desire to build a house with limited resources, trend of building largest house in smaller plot of land emerged. Thicker walls etc were not affordable from both the angles of land area and cost. Therefore the need of sleeker construction developed and scientists started exploring the way out.

To compensate the deficiency of masonry structures against tensile forces, mild steel bars found it’s utility to make the structures strong and sleek. Concept of RCC(Reinforced cement concrete evolved. François Coignet was the first to use iron-reinforced concrete as a technique for constructing building structures. In 1853, Coignet built the first iron reinforced concrete structure, a four-story house in the suburbs of Paris. His descriptions of reinforcing concrete suggests that he did not do it for means of adding strength to the concrete but for keeping walls in monolithic construction from overturning. Thereafter, In 1854, English builder William B. Wilkinson reinforced the concrete roof and floors in the two-story house he was constructing. His positioning of the reinforcement demonstrated that, unlike his predecessors, he had knowledge of tensile stresses.

Before the 1870s, the use of concrete construction, though dating back to the Roman Empire, and having been reintroduced in the early 19th century, was not yet a proven scientific technology. Mr. T Hyatt, published a report entitled An Account of Some Experiments with Portland-Cement-Concrete Combined with Iron as a Building Material, with Reference to Economy of Metal in Construction and for Security against Fire in the Making of Roofs, Floors, and Walking Surfaces, in which he reported his experiments on the behavior of reinforced concrete. His work played a major role in the evolution of concrete construction as a proven and studied science. 

Mr. E L. Ransome, an English engineer, was an early innovator of reinforced concrete techniques at the end of the 19th century. Using the knowledge of reinforced concrete developed during the previous 50 years, Ransome improved nearly all the styles and techniques of the earlier inventors of reinforced concrete. Ransome's key innovation was to twist the reinforcing steel bar, thereby improving its bond with the concrete. In April 1904, Julia Morgan, an American architect and engineer, who pioneered the aesthetic use of reinforced concrete, completed her first reinforced concrete structure.

In 1906, the National Association of Cement Users (NACU) published Standard No. 1 and, in 1910, the Standard Building Regulations for the Use of Reinforced Concrete. 

How steel reinforcement helps – a concrete is nothing but an artificial stone, manufactured by man, binding fragments of natural rocks with cement. Any concrete or natural rocks are very strong in compression but very weak under tensile of bending loads. To overcome this shortcoming of concrete, engineers, leveraged the favourable tensile properties of mild steel, introduced MS round bars / rods in the tensile zones of concrete members. Off late twisted MS bars are being used in 100 out of 100 structures for its better bonding with the concrete. Twisted MS bars – TMT or HYSD enabled engineers to design mind blowing unique structures with high strength, durability, sleek and aesthetic, which probably were unthinkable before the start of usage of reinforcing steel.