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:

[UPSC Civil Services Exam – 2020 Prelims]

(a) 1, 2 and 3 only

(b) 2, 3 and 4 only

(c) 4 and 5 only

(d) 1 and 5 only

Answer: (a)        

Explanation:

• Statement 1 is correct as the use of copper slag in cement and concrete can provide both environmental and economic benefits, particularly in areas where a large amount of copper slag is produced.
• Statement 2 is also correct as the production of cold asphalt mix is economically feasible due to low investment in equipment, and it can be used for both initial construction and recycling of asphalt pavements.
• Statement 3 is correct as geotextiles are mainly used in road construction to improve soil structure and prevent erosion, while allowing water to drain off.
• However, statements 4 and 5 are incorrect as Portland cement and hot asphalt mix are major CO2 emitters, and hot mix asphalt is primarily made up of aggregates and asphalt binder, not crude oil.