29 March 2020

Table of Contents for Special Focus- CONCRETE

Special Focus - CONCRETE

Concrete gain

American researchers have come up with a new formulation which purports to bring down greenhouse gas emissions in the concrete industry by reducing the ratio of calcium to silicate. India’s Concrete Industry, with its current emphasis on sustainability and technology, can benefit hugely from adopting the new process. CONSTRUCTION OPPORTUNITIES reports

It is a no brainer that concrete is the most used material used in construction on this planet – its present usage is three times more than that of steel – and consequently a big contributor to global warming. Various assessments have found that it produces as much as a tenth of greenhouse gas emissions generated by industry.

There is now a new study which claims that under a new method of production of concrete emissions could be subtracted by close to 50 per cent and the result is more stronger and durable material. The outcome can be related to the analysis of the structure of concrete which is nothing but carefully balanced mix of sand, cement, aggregates and water. It is known that while cement plays the role of a binder modifying the characteristics and uses of concrete, aggregates help to retain the intrinsic properties of rocks from which they are derived. The colour, chemical and physical attributes of aggregates have a bearing on the durability, aesthetics and mechanical properties of concrete.

Cement is produced by cooking calcium-rich material, usually limestone, with silica-rich material like clay at 1500 degrees Celsius, contributing to a hard mass called clinker which is further ground into a powder. The decarbonation of limestone and the heating of cement are largely responsible for most of greenhouse-gas output. A group of senior researchers led by scientist Roland Pellenq; Professors Krystyn Van Vliet, Franz-Josef Ulm, Sidney Yip, and Markus Buehler have found that reducing the ratio of calcium to silicate can not only bring down emissions but actually produce qualitatively better and stronger concrete.

The work is the culmination of five years of collaborative research by the team from CNRS where Pelleng is research director and MIT where Ulm is director of the Concrete Sustainability Hub. Incidentally the Concrete Sustainability Hub is supported by the Portland Cement Association and the Ready Mixed Concrete Research and Education Foundation.

It is pointed out that while in conventional cements the calcium-to-silica ratio ranges from about 1.2 to 2.2, with 1.7 accepted as the standard, the resulting molecular structures have never undergone detailed analysis or comparison. Pellenq and his associates have assessed that he optimum mixture is not the one being used currently but rather a ratio of about 1.5. The scientist is of the view that since the ratio varies the molecular structure of the hardened material progresses from a tightly ordered crystalline structure to a disordered glassy structure. The verdict now is that ratio of 1.5 parts calcium for every one part silica is “a magical ratio” because at that point the material can achieve “two times the resistance of normal cement, in mechanical resistance to fracture, with some molecular-scale design.”

These observations have been validated against large body of experimental data. Since emissions related to concrete production are estimated to represent 5 to 10 percent of industrial greenhouse-gas emissions any reduction in calcium content in the cement mix will have an impact on the CO2, it is pointed out. Pelleng actually goes on to say the reduction in carbon emissions could be as much as 60 percent.
What the new formulation does is to contribute to the overall mechanical strength. Since the material is glassy and less crystalline, the possibility of residual stresses in the concrete are eliminated and it becomes more fracture resistant. It is because of these strong attributes it is now being felt that the latest formulation could prove to be useful in areas like the Oil & Gas sector where the usage of cement around well casings is a key to preventing leakages and blowouts.

This could be a huge breakthrough in the area of concrete research – its areas of applications around the world and for countries like India are huge. Thus far the work has been at a molecular level of analysis. The scientists next hope to ensure that “these nanoscale properties translate to the mesoscale” which translated means the engineering scale of applications for infrastructure, housing, and other uses.





With India stepping up its infrastructure agenda at a fast pace and concrete being an essential requirement of infrastructural development its importance cannot be further underlined. It is significant that the World of Concrete India will return in India next month for three days (November 13-15) at the Hitex Exhibitions Centre in Hyderabad. An extension of the World of Concrete owned and produced by Hanley Wood Exhibitions in Dallas, Texas, and held in Las Vegas annually, the Indian edition is being jointly organised by Hanley Wood USA and Inter Ads Exhibitions India and supported by the Indian Concrete Institute .The events aim to address new developments in concrete and construction, especially in the infrastructural sphere. World of Concrete India 2014 will be a great platform for suppliers from the commercial concrete and construction industry in India to showcase innovative products, state-of the-art technologies, latest tools and equipment used in the industry. Business opportunities, networking services, one to one meeting with potential customers and presentation of some of the important products like aggregate processing, aggregates, anchors and fasteners, batching equipment, cleaning materials & equipment, coatings inspection, measurement, coatings, stains, sealers, computer hardware, software, cranes, cutting & drilling, decorative concrete, demolition equipment & materials by the exhibitors will be some of the highlights of this event. World of Concrete India will be attended by construction engineers, technical and professional experts related to concrete industry. These experts and industry leaders can have a discussion with each other about the modern market trends associated with this sector.


World of Concrerte History

World of Concrete USA - The 40 Year History (1975-2014) Introduced to the commercial construction industry in Houston, Texas in February 1975, World of Concrete presented 77 exhibiting companies in 22,200 net square feet of exhibit space with 1,550 construction industry professionals in attendance.

40 years later, World of Concrete now boasts more than 1,300 exhibiting companies and 50,000 registered industry professionals in more than 550,000 square feet of exhibit space. The addition of World of Masonry and Technology for Construction expanded the range of attendees to include these important segments of the construction industry.


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