Precast concrete technologies

The use of precast segments by tunnel boring machines (TBMs) in underground construction is becoming the dominant and cost-effective approach for traffic, rail, metro, water and wastewater tunnels systems . The justifications for the use of precast concrete segments are based on the speed of construction, elimination of temporary support, serving as the reaction frame for boring, the combination of initial and final support, choice support for TBM bored tunnels in soft ground and weak fractured rock . This chapter addresses the criteria and fundamental importance of the parameters that affect the strength, ductility and durability of the precast concrete materials used in tunnel segments using the TBM-type machines. Fundamental contributions of the mix components, design parameters, early age and long-term properties, as well as the durability of the material, are addressed.