UPSC Prelims 2020 question on Eco Friendly Road Construction

Statement by statement

Option 1 is correct: The use of copper slag in cement and concrete provides potential environmental as well as economic benefits for all related industries, particularly in areas where a considerable amount of copper slag is produced.

Option 2 is correct and Option 4 is not correct: Cold asphalt mix is produced by mixing unheated mineral aggregate with either emulsified bitumen or foamed bitumen. Unlike hot mix asphalt (HMA), cold asphalt mix does not require any heating of aggregate which makes it economical and relatively pollution-free (no objectionable fumes or odours). It is also suitable for use in remote areas. Hot mix asphalt is energy intensive and emits enormous amounts of carbon dioxide (CO2) as well as numerous other pollutants — so it is NOT preferred for environmental sustainability.

Option 3 is correct: Geotextiles are mostly used in road construction, especially to fill gaps between the roads to improve soil structure. It helps to prevent the erosion of soil but allows the water to drain off.

Option 5 is not correct: Reducing the Portland cement that binds concrete together is energy intensive and emits enormous amounts of CO2 as well as numerous other pollutants.