A Concrete Belief

Today, concrete is one of the most commonly used building materials around the globe, irrespective of climatic regions and the design purpose. According to UN Environment, concrete is the second most used material on the Earth after water. Its high strength, durability, versatility, and affordability made the material most preferable in all periods. Artifacts from ancient Egypt, Greek, China, and many regions all around have showcased the use of limestone composites in building construction.

Joseph Davidovits, a French chemist in 1974, proposed that the blocks of the Great Pyramids of Giza, were set using limestone slurry. Though Egyptologists have rejected his proposal, Charles Bremmer in 2006 claimed that Pyramids were built with concrete rather than rocks. Scientist around the world is looking for concrete evidence of geopolymer binders and limestone composites in artifacts of the great pyramids. The reports of Schliemann’s excavation of Mycenaean archaeological sites showcase how Greeks used concrete in the flooring of royal courts in Mycenaean palaces. In the East, in China, a special ingredient was used in the composition of concrete. Because of this, the concrete has great control over the shrinkage, though its strength is average. According to the study led by Bingjian Zhan of the Zhejiang University of China, the presence of Amypectin, a carbohydrate found in rice is traced on the 600-year-old city wall of Nanjing, mortar samples of halls and gardens of the Forbidden City. According to the journal Accounts of Chemical Research, Amypectin is found in rice with lime’s calcium carbonate formation of calcium carbonate crystals resulting in a more tightly bonded mixture that is highly water-resistant.

Romans successfully developed high-quality hydraulic cement made of lime and pozzolana. They called it “caementum”, whose composition is close to the modern Portland cement. “Opus caementum”, the Roman concrete is used extensively in public and commercial buildings. Pantheon’s dome is the largest unreinforced concrete dome standing for more than 2000 years long resisting many natural disasters, wars, and climatic change.

The formation of stratlingite crystals, which are similar to microfibers, is formed in the mixture of lime and volcanic matter to prevent the spread of microscopic cracks. Pure compression members and structural forms are designed in this period with the structural qualities of the concrete available.

Modern concrete is a mixture of Portland cement, aggregate, sand, and water. It is an excellent material that is easily available, economical, and workable without compromising on its strength. Its durability to resist water and high temperatures, its ability to cast in any desired shape whose strength doesn’t deteriorate with age makes it a desirable building material in the world. Admixtures and steel rebar have improved the strength, durability, and workability of concrete to higher folds. Prefabricated concrete modules cast in reinforced steel cages as structural members allowed designing a form with larger overhangs to create terrace gardens in Habitat 67 by Safde Moshe.

For centuries together, RCC dominated the construction industry and it allowed cities to develop vertically. Without concrete, nations would have suffered to accommodate growth and respond to the fast-growing population.

The environmental impact of concrete is one of the major issues today. Concrete alone accounts for 5 percent of annual carbon dioxide released by man. Karen Scrivener, Swiss Federal Institute of Technology says that concrete is the most used material in the construction industry because of its low impact. She also said that, if the concrete is replaced with any material on the Earth, it would have a bigger carbon footprint. When you look at the composition of modern concrete, the making of Portland cement is responsible for most of the CO2 released and higher energy consumption. Thus, to reduce the environmental impact of concrete, innovations are being focused on reducing the amount of concrete used by increasing the strength of the concrete or by reducing the amount of cement used. Fiber-reinforced concrete is one of the innovations that increased the tensile nature of the concrete, resulting in an increased impact strength and a decreased crack growth. The lightweight and increase in tensile nature of the concrete allowed the design of concrete members in organic forms ever imagined. Addition of steel fiber to concrete increases durability, resistance to bending, cracking. Carbon fibers have high stiffness, high tensile strength, low weight, high chemical, and thermal resistance. Carbon stored in built mass is nothing but carbon sequestration resulting in reducing the amount of carbon released in the environment by concrete.

The popularity of concrete is increasing every day with ongoing innovations to the need of the construction industry. Along with technological and engineering interventions in built materials, design is also equally responsible for aiming at reducing concrete usage. The way concrete has been evolving since ancient times shows the potential the material got to address the environmental issues we face today. Along with the time and need of the construction industry, innovations and advancements led to changes in concrete composition over the period. Its versatility, durability, and strength made it a choice material both in architectural and engineering fields. Finding a perfect vision is more important than finding an engineering solution here. It is crucial to identify how to use concrete and how not to use concrete in the construction industry along with its green material innovations toward a sustainable tomorrow.

AUTHOR

HARIKA GANDI

My name is Harika, I am an Architect, Artist, and Professor with over 5 years of experience working closely with Architects, Artists, International experts, policymakers & students across the country. I graduated with Bachelors of Architecture from Andhra University and earned my Masters degree in Psychology from Andhra University. Being a continuous learner, I am currently pursuing my Master in Environmental Design from JNAFAU, Hyderabad. Besides being the co-founder of the firm Sargah Architects, my true passion for working with young learners, sharing knowledge, and interacting with them has motivated me to pursue my career in teaching where I work as an Assistant Professor at Sri Venkateswara College of Architecture, Hyderabad and Visiting Faculty at Sri Venkateswara College of Fine Arts, Hyderabad. My teaching philosophy is to create a community of learners who are design thinkers, who create sustainable solutions and are rooted to Human and Environmental centric designs, making this world a better place to live in.

SARMADAMADHULIKA KONE

An architect and urbanist whose work is inclined towards developing socially responsible design solutions. She worked on multiple residential towers in Navi-Mumbai, 2015-16. She is now the Founder and Principal Architect at Sagṛaḥ Architects, Hyderabad, India. She received her Master of Planning in Urban Development from Maulana Azad National Institute of Technology, India in 2017 and a Bachelors of Architecture from the School of Planning and Architecture, Vijayawada, India in 2014. As an urbanist, her research interests are in People-centric Cities and ICT interventions in Participatory Planning. Her latest publication is “Smart Public Participation: An inquiry into the role of process and technology” in the book ICT Solutions for Improving Smart Communities in Asia, 2021.