Question 95 from UPSC CSE 2020 - ENVIRONME NT

Question

In rural road construction, the use of which of the following is preferred for ensuring environmental sustainability or to reduce carbon footprint?
1. Copper slag
2. Cold mix asphalt technology
3. Geotextiles
4. Hot mix asphalt technology
5. Portland cement
Select the correct answer using the code given below:

IASCODEX · Accepted Answer

Correct Option: A. 1, 2, and 3 only

Strategy: The strategy prioritizes construction methods and materials that offer significant sustainability benefits and a lower carbon footprint. This involves identifying and selecting environmentally advantageous options while ruling out those with adverse impacts. Key sustainable choices include:

*   **Copper slag:** A waste product from the copper industry, its reuse in construction reduces landfill and environmental impact.
*   **Cold mix asphalt:** This technology saves energy and reduces emissions by eliminating the need for heating.
*   **Geotextiles:** These synthetic fabrics enhance resource efficiency through soil stabilization in road construction.

Conversely, materials like hot mix asphalt, due to its high-temperature processes and significant fuel use, and Portland cement, a major industrial source of CO2, are deemed undesirable for sustainability goals. By excluding options containing these less sustainable choices, the strategy leads to the selection of option A.

Key Info: This section provides detailed information on various materials and technologies, outlining their environmental characteristics:

**Copper Slag**
*   A byproduct of the copper smelting process.
*   Increasingly used as a partial replacement for fine aggregates in road construction and cement concretes.
*   Promotes waste utilization and reduces the need for natural materials.

**Cold Mix Asphalt**
*   Technology involves blending bitumen emulsion or foamed bitumen with aggregates at ambient temperature.
*   Greatly reduces energy use and emissions compared to conventional hot mix asphalt.
*   Well-suited for rural and remote locations and supports the recycling of old pavement materials.

**Geotextiles**
*   Permeable synthetic fabrics applied in road construction.
*   Functions include separating, filtering, reinforcing, protecting, or draining soils.
*   Aids sustainable construction by optimizing material usage and enhancing road longevity.

**Hot Mix Asphalt**
*   Relies on high-temperature processes.
*   Demands significant fossil fuel consumption and contributes to greenhouse gas emissions.

**Portland Cement**
*   Manufacture is highly energy-intensive.
*   Involves the calcination of limestone, which emits large volumes of CO2.
*   Its production is a leading contributor to industrial carbon emissions globally.

**Sustainable Infrastructure Trends**
*   The focus is shifting towards:
    *   Recycling industrial byproducts.
    *   Energy-saving technologies (e.g., cold mixes).
    *   Geosynthetics.
*   This shift prioritizes these over materials with high embodied energy.

IASCODEX · Answer

Option B: 2, 3, and 4 only

IASCODEX · Answer

Option C: 4 and 5 only

IASCODEX · Answer

Option D: 1 and 5 only

In rural road construction, the use of which of the following is preferred for ensuring environmental sustainability or to reduce carbon footprint? Copper slag Cold mix asphalt technology Geotextiles Hot mix asphalt technology Portland cement Select the correct answer using the code given below: