Durability is one of the focal points of recent research on the behavior of new blended cement matrices in aggressive environments. The material selected for this study was ceramic waste (CW) rejected by Spanish manufacturers, primarily for reasons such as unsuitable kiln temperature or dimensional or mechanical failure. The resistance of CW-containing cement pastes to three aggressive environments (SO42-, Cl-, and substitute seawater) was tested using the Koch-Steinegger method in this in-depth analysis of the effect of CW on the chemical resistance of new blended matrices. The samples were also tested for performance in freeze-thaw cycles. The reaction mechanism was analyzed using X-ray diffraction (XRD), pore-size distribution, scanning electron microscopy (SEM), and backscattered electron images (BSE) with energy-dispersive X-ray (EDX) techniques. The results showed that CW contributed to cement resistance to such media; this enhancement of its mechanical properties was the result of the pozzolanic reaction induced by the addition of CW.