This volume presents challenges in transportation infrastructures and geotechniques, advancements in recycling, soil stabilization and reinforcement technologies, and assessments of roadway conditions using modern tools and techniques. The articles presented in this volume focus on fundamental investigations on various aspects of civil engineering materials and structures. The scope of this volume is the application of findings for solving problems in geotechnical, pavement, concrete and transportation engineering using through smart, green and emerging techniques. The primary audience of this work will be researchers, professionals, and practitioners around the world. This volume is based on contributions to the 6th GeoChina International Conference on Civil & Transportation Infrastructures: From Engineering to Smart & Green Life Cycle Solutions -- Nanchang, China, 2021.