Currently, the active use of ground granulated blast-furnace slag as a cement substitute is being promoted as part of carbon neutrality initiatives. Additionally, the use of recycled aggregate concrete is encouraged to support resource recycling. It has been reported previously that environment friendly concrete using recycled aggregate and ground granulated blast-furnace slag as the solidifying material can be applied to the pavement subgrade. Urban areas, particularly the Tokyo metropolitan area, are implementing pavement heat island countermeasures to combat the issue of summer heat. This study investigated the applicability of environment-friendly concrete incorporating ground granulated blast-furnace slag and alkali-activated material as solidifying materials, along with low-quality recycled aggregate, for use in interlocking blocks to reduce road-surface temperature increase. The results revealed that this environment-friendly concrete met the flexural strength quality standards and effectively mitigated road-surface temperature increase, confirming its suitability for use as interlocking blocks.