Converting construction and demolition waste (CDW) into secondary raw materials is one of the priorities of environmental policy and circular economy strategy. This study analysed the variation in eco-efficient paste reactivity with OPC replacement ratio (5% to 10%) and hydration time (2 d, 28 d and 90 d). Three types of CDW were explored: two (calcareous and siliceous) consisting of fine (<5 mm) concrete waste and one in laminated glass (<40 mm). Further to the mineralogical phases identified at the aforementioned percentages, the four materials, i.e., the three types of CDW-blended cements and the OPC reference, were similarly reactive. The primary hydration products, C-S-H gels, C4AH13 and C4AcH11, ettringite and portlandite, were the same as observed in OPC hydration. These findings attest to the scientific viability recycling such CDWs as mineral additions in eco-cement manufacture and consequently eliminating the need for stockpiling these materials at recycling/storage plants.