The scientific activities of Theme 2, which relate to "Resilient and efficient infrastructure", were marked in 2018 by current events, which reminded us of the importance of maintaining our existing, sometimes ageing, infrastructure. The national road audit identified a significant need for investment to upgrade and maintain infrastructure that is subjected to increasing use and exposed to new types of stresses, as a result of climate change in particular. The imperatives of the ecological and solidary transition also require us to seek materials that are less energy-consuming and more environmentally friendly, without sacrificing mechanical properties and durability. The infrastructure must not only be economical in its own right, but also help to reduce the environmental impact of mobility. Modifying infrastructure is one of the goals we are pursuing, and there have already been some achievements in this area. The development of a circular construction economy is a second goal that is described in this activity report. Finally, new transport infrastructure that will help bring about the ecological and energy transition, particularly in the context of the 5th Generation Road, and new renewable energy production and transmission infrastructure, complete the picture for the year 2018.