+
Combating Chloride
Concrete

Combating Chloride

The backbone of construction, concrete structures that are durable and can sustain seismic activity are made by reinforcing steel in concrete. For dynamic structures such as flyovers and bridges, reinforcement is a must. Today’s multi-storeyed buildings and malls with straight or curved shapes also require reinforced concrete structures (RCC). However, a key negative is the corrosion of reinforcement.

Steel can be imbedded in concrete in any shape. The steel frame of a structure is first erected and then covered with concrete. However, the presence of this steel can result in corrosion of an RCC structure. So, how do chlorides reach steel in the embedded structure? 

The fact is, concrete does not seal the RCC structure because it is porous so it always retains some moisture. Second, the outer layer of concrete, which is called ‘cover’, is always in contact with moisture and pollutants whose concentration varies from place to place and season to season. For instance, a relatively dry environment like Delhi or Rajasthan will have lower moisture and pollutants compared to a wet environment as in Mumbai and Chennai, which have higher humidity. Further, a highly populated city and industrial city may have a high concentration of pollutants such as carbon dioxide and sulphur dioxide and coastal cities also have chlorides in the atmosphere. All these pollutants enter the porous concrete structure by hitting the cover and then making their way into the steel through the concrete pores. As soon as a minimum concentration of these pollutants reaches the steel-concrete interface, the corrosion begins as in Figure 1.

 About the author: Professor AS Khanna is retired from IIT Bombay and is Chairman, SSPC India.

To read the full story, CLICK HERE.


The backbone of construction, concrete structures that are durable and can sustain seismic activity are made by reinforcing steel in concrete. For dynamic structures such as flyovers and bridges, reinforcement is a must. Today’s multi-storeyed buildings and malls with straight or curved shapes also require reinforced concrete structures (RCC). However, a key negative is the corrosion of reinforcement.Steel can be imbedded in concrete in any shape. The steel frame of a structure is first erected and then covered with concrete. However, the presence of this steel can result in corrosion of an RCC structure. So, how do chlorides reach steel in the embedded structure? The fact is, concrete does not seal the RCC structure because it is porous so it always retains some moisture. Second, the outer layer of concrete, which is called ‘cover’, is always in contact with moisture and pollutants whose concentration varies from place to place and season to season. For instance, a relatively dry environment like Delhi or Rajasthan will have lower moisture and pollutants compared to a wet environment as in Mumbai and Chennai, which have higher humidity. Further, a highly populated city and industrial city may have a high concentration of pollutants such as carbon dioxide and sulphur dioxide and coastal cities also have chlorides in the atmosphere. All these pollutants enter the porous concrete structure by hitting the cover and then making their way into the steel through the concrete pores. As soon as a minimum concentration of these pollutants reaches the steel-concrete interface, the corrosion begins as in Figure 1. About the author: Professor AS Khanna is retired from IIT Bombay and is Chairman, SSPC India.To read the full story, CLICK HERE.

Next Story
Infrastructure Urban

Digital First: Bridging the Skilled Talent Gap in India’s Construction Sector

India stands at a defining juncture in its economic journey as it accelerates toward becoming a US$7 trillion economy by 2030. India’s construction sector, encompassing infrastructure and real estate development will play a pivotal role in its economic transformation. Expansion in developments such as the national highways, smart cities, airports, metro networks, logistics hubs, housing, etc. underscores the physical expression of India’s development ambition. The construction sector is already the second-largest contributor to India’s GDP, accounting for nearly 18 per cent of total..

Next Story
Infrastructure Transport

Titagarh Rail to Raise Rs 2 billion via Preferential Allotment to Promoters

Titagarh Rail Systems has announced a proposal to raise approximately Rs 2 billion through a preferential issue of 21,16,402 convertible warrants to members of its Promoter Group. The board of directors approved the move at its meeting held on July 9, 2025, subject to shareholder and regulatory approvals. The warrants, priced at Rs 945 each, will be allotted to Mrs Rashmi Chowdhary and Mr Prithish Chowdhary in line with Chapter V of SEBI’s ICDR Regulations. Each warrant is convertible into one equity share of ₹2 face value within 18 months from the date of allotment.   ..

Next Story
Real Estate

Hindware Strengthens Eastern Footprint with New Brand Store in Kolkata

Bathware major Hindware has expanded its retail footprint in West Bengal with the launch of a new state-of-the-art brand store in Ichapore, Kolkata. This marks the company’s fourth brand store in the city and 30th in the state, underlining its strategic focus on the eastern market. The newly launched store, operated by Tirupati Sales Corporation, showcases the entire spectrum of Hindware’s bathware offerings, including sanitaryware, faucets, showers, basins, and products from its premium lines — Queo and the Hindware Italian Collection. It is aimed at providing an immersive experien..

Advertisement

Advertisement

Subscribe to Our Newsletter

Get daily newsletters around different themes from Construction world.

STAY CONNECTED

Advertisement

Advertisement

Advertisement

Advertisement

Talk to us?