Textile Reinforced Cementitious (TRC) sandwich compositesare innovative construction materials composed of two slenderTRC facings, and a thick thermal and acoustic insulating core.Their non-corrosive nature allows for slender structures,resulting in a reduction of the cement used, and therefore adecrease of the negative impact on the environment. Thesandwich technology brings superior bending resistance whileenforcing the lightweight nature of the composite. Despite thenumerous advantages of TRC sandwich composites, they presenta complex and possibly unpredictable fracture behavior, andmanufacturing issues such as a weak interlaminar bond andtherefore, there is a need for status verification in the differentstages of their service life: at the manufacturing stage (curing),final product quality (manufacturing defects), deteriorationduring use (damage accumulation). There is currently no reliablenon-invasive inspection protocol that assesses the curing of thecementitious facings, and provides for quality control anddamage monitoring.Along this study, a combination of Non-Destructive Testing(NDT) techniques is employed to provide a protocol that allowsmonitoring the composite from the hardening of the cementitiousfacings, enables quality control, and finally, supports damagecharacterization. Electromagnetic millimeter wave (MMW)spectrometry is employed for the first time in this kind ofmaterial to monitor the hydration of cementitious media, to carryour quality control, and to characterize damage. Additionally,passive, and active elastic wave-based NDT techniques, likeAcoustic Emission (AE) and Ultrasound inspection, respectively,are also used in combination with Digital Image Correlation(DIC) to characterize the material along its lifetime, and to serveas a benchmark for MMW spectrometry. This thesis summarizesthe results of an extensive experimental campaign andhighlights the innovative contributions. Previously unknownrelations between electromagnetic properties measured byMMW and mechanical properties obtained with ultrasoundinspection are revealed due to the hydration reactions thatdictates the permittivity and stiffness development. AE duringproof-loading reveals the effect of manufacturing defects due tothe local stress field variations that they impose undermechanical tests. In addition, cracking and debonding leave astrong fingerprint on the electromagnetic transmission, enablinga multi-spectral methodology for structural health monitoring(SHM) of such innovative components during their lifetime.