This study presents the design and testing of a scaled Tunnel Boring Machine (TBM) injector for two-component grout, developed to emulate the injection system of a full-scale TBM. The injector facilitates the turbulent mixing of two liquid components, A and B, just prior to injection, ensuring a homogeneous mix, rapid gelation and subsequent hardening. Laboratory tests were conducted to compare the properties of grout samples casted using the scaled TBM injector against those casted by hand, according to the standardised procedure set-up at Politecnico di Torino. The results, based on the mechanical characterisation, highlighted that samples produced with the scaled TBM injector are comparable to those cast by hand, with the injector samples exhibiting reduced air incorporation compared to the ones casted by hand. This study underscores the potential of the scaled TBM injector in producing high-quality two-component grout useful for characterisation phase and studies to be performed before the application in construction sites.

Keywords: backfilling, two-component grout, EPB, two component grout injector, laboratory injector.