Warm mix asphalt using aspha-min (synthetic zeolite) has been state-of-the-art for many years now.
Recently in Germany, we had the opportunity to demonstrate the laying of a warm mix wearing course (AC 11 DN 50/70) at 120 - 130 °C with only 3 °C ambient temperature. And again, compaction was accomplished effortlessly.
Why demonstrate a warm mix 25 years after its inception? Simply because most industries and buyers were reluctant or unable to accept extra cost for more sustainability in asphalt road construction. However by 2025, Germany will face a significant tightening of exposure limit values for vapours & aerosols from bitumen - to the extent that only a tenth of the currently accepted value will be permissible.
As has been repeatedly shown, a reduction of temperature in the mix by 30 K will reduce emissions (vapours & aerosols) by around 75%. This, in combination with extraction devices at pavers, might literally "pave the way" to master this challenge - even as cold weather paving. Further measuring and evaluation might be necessary, guidelines need to be changed, but eventually, there is light at the end of the tunnel.
On a side note: aspha-min is one of few additives that will leave both performance and recyclability of the asphalt fully untouched. For more detail, do get in touch through firstname.lastname@example.org