Innovative and smart building materials (Lec by Dr. Iyer Vijayalaxmi Kasinath)

Innovative Building Materials: A Sustainable Revolution 🏗️

The construction industry is a major global concern, consuming 30-40% of the world's total energy and contributing to one-third of all greenhouse gas emissions. The high energy consumption and environmental impact of conventional materials like cement, steel, and aluminum necessitate a shift toward sustainable and innovative solutions. These new materials aim to reduce the carbon footprint, conserve energy, and utilize waste products.

Carbon Footprint refers to the total amount of greenhouse gases (GHGs) produced by an activity, often expressed in equivalent tons of carbon dioxide (CO2​). In building materials, this includes emissions from extraction, manufacturing, and transportation.

Need and Characteristics of Innovative Materials

The push for innovative materials is driven by the need to meet global decarbonization goals, reduce resource depletion, and mitigate environmental pollution. Key characteristics of these materials include:

  • Energy Efficient: They reduce the energy needed for both production and building operation.

  • Renewable: Made from sources that can be naturally replenished, such as plant-based or recycled materials.

  • Recyclable & Reusable: Can be repurposed at the end of their lifecycle, reducing waste.

  • Durable & Non-toxic: They provide a long service life and are free from harmful chemicals.

  • Locally Sourced: Materials are procured from nearby regions, which reduces transportation costs and emissions.

Sustainable Alternatives to Concrete and Brick

Traditional concrete and bricks have significant environmental drawbacks. The production of their components depletes natural resources and generates substantial greenhouse gases. Innovative alternatives address these issues by using new raw materials and methods.

  • Permeable Concrete: This is a special type of concrete with an open pore structure, a network of interconnected voids that allow water and air to pass through. This is created using gap-graded coarse aggregates with minimal fine aggregates.

    • Applications: It's excellent for flood protection, urban drainage, and recharging groundwater.

  • Nanocellulose Composite Brick: An eco-friendly brick made from nanocellulose, a natural polymer composed of nanosized cellulose fibrils from plant cell walls.

    • Properties: It's renewable, biodegradable, and offers high mechanical strength and thermal conductivity.

    • Challenge: Large-scale production is currently complex and energy-intensive.

  • Agro-Bricks: Construction materials that incorporate agro-waste—residues from agricultural products like rice husk, sugarcane bagasse, and cotton stalk.

    • Benefits: They are cost-effective, durable, and have low thermal conductivity, which means they provide excellent insulation by slowing down heat transfer.

    • Examples:

      • Date Palm Fibers (DPF): Known for their superior thermal insulation.

      • Rice Husk Ash (RHA): A product of incinerated rice husk. Higher RHA percentages can increase water absorption (the amount of water a material can hold) but may decrease compressive strength (the ability to withstand being crushed).

      • Fabrick: A composite brick made from cotton and textile ash waste, offering better insulation than traditional concrete bricks.

Smart Building Materials: The Future of Architecture 🧠

Smart materials are highly engineered materials that can intelligently respond to environmental stimuli like stress, temperature, or electric fields. Their "intelligence" allows them to change their properties in a controlled way.

Classification and Types

Smart materials are classified based on their interaction with energy stimuli:

  1. Type 1: Materials that change their properties.

    • Shape Memory Alloys: Metals that revert to a pre-defined shape when heated.

    • Thermochromic Materials: Materials that change color in response to temperature.

  2. Type 2: Materials that transform energy.

    • Photovoltaic (PV) Materials: Convert light energy into electricity.

    • Piezoelectric Materials: Generate an electric charge when subjected to mechanical stress.

Key Smart Material Applications

  • Self-Maintaining Materials: These can self-heal by repairing cracks or damage, extending their service life and durability.

  • High-Insulating Materials: They provide exceptional insulation. Aerogel is known for its very low density and thermal conductivity, while ETFE (Ethylene Tetrafluoroethylene) is a transparent, Teflon-based material used in roof systems for superior insulation.

  • Energy-Generating Materials: These materials produce energy. Building-Integrated Photovoltaics (BIPVs) are solar cells integrated directly into a building's components, like facades or roofs.

Advantages and Challenges

Smart materials offer many advantages, including enhanced durability, long-term cost efficiencies, and improved resilience to extreme events. However, widespread adoption faces several challenges:

  • High Cost: The initial cost of production and installation can be a barrier.

  • Lack of Awareness: Limited public and professional knowledge about their capabilities.

  • Implementation: Overcoming these challenges requires public promotion and showcasing successful projects to build confidence and increase demand.

Building Examples:

  • The Netherlands Pavilion uses organic transparent solar cells to power a system that harvests water from the air.

  • The Sumu Yakushima Regenerative Residence integrates mycelium, a type of fungus, to strengthen the soil, demonstrating a "regenerative architecture" approach.


Reference: 

https://www.youtube.com/watch?v=Cu1k_fsuwUE&list=PLyqSpQzTE6M8lKQO8IypiuOeLnnWuzldm&index=1&ab_channel=NPTEL-NOCIITM

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