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: (2020)
Options
1) 1, 2 and 3 only
2) 2, 3 and 4 only
3) 4 and 5 only
4) 1 and 5 only
Correct Option
The question asks for materials and technologies preferred for environmental sustainability or to reduce the carbon footprint in rural road construction. Options 1, 2, and 3 align with this objective.
- 1. Copper slag: This is a by-product of copper smelting. Its use as a partial replacement for natural sand or aggregates in road construction helps in the effective utilization of industrial waste, reduces the demand for virgin natural resources, and minimizes landfill burden. It is generally non-hazardous and contributes to a circular economy.
- 2. Cold mix asphalt technology: Unlike hot mix asphalt, this technology does not require heating bitumen to high temperatures during mixing and laying. This significantly reduces energy consumption, primarily from fossil fuels, leading to lower greenhouse gas emissions, including CO₂, and improved air quality. It is particularly suitable for rural and low-volume roads.
- 3. Geotextiles: These are permeable fabrics used in civil engineering applications, including road construction, for separation, filtration, reinforcement, protection, or drainage. When made from natural fibers like coir, jute, or bamboo, they are biodegradable and offer an environmentally friendly alternative. They can reduce the need for conventional aggregates, enhance soil stability, and extend pavement life, thereby reducing maintenance and material consumption over time.
Incorrect Options
- 4. Hot mix asphalt technology: This conventional method involves heating bitumen and aggregates to high temperatures (typically 150-180°C) for mixing and compaction. This process is energy-intensive, consuming significant amounts of fossil fuels, and results in substantial emissions of greenhouse gases (like CO₂) and other pollutants. Therefore, it is not preferred for reducing the carbon footprint.
- 5. Portland cement: While a fundamental material in construction, the production of Portland cement is a major contributor to global CO₂ emissions. The calcination of limestone (CaCO₃) to produce lime (CaO) releases CO₂, and the high temperatures required for clinker production consume significant energy, often from fossil fuels. Its extensive use is therefore not considered environmentally sustainable in terms of carbon footprint reduction.