Blends of polyblend and bitumen, when used, help to increase road life by a factor of three. What is the reason?

Blends of polyblend and bitumen, when used, help to increase road life by a factor of three because:

i) In India, the weather is mainly hot and extremely humid and plastic increases the melting point of bitumen and prevent it from melting.

ii) Rainwater is prevented from seeping in through the roads due the presence of plastic.