Recycled concrete powder on cement mortar: Physico-mechanical effects and lifecycle assessments

Preventing the indiscriminate disposal of wastes and reducing environmental pollution via the use of supplementary cementitious material cannot be over-emphasized. This research examines the characteristics of Recycled Concrete Powder (RCP) and its potential use as a partial replacement for cement in concrete production. Waste concrete was sourced and recycled, obtaining RCP. The RCP samples were characterized through various microscopic techniques. The effects of RCP on cement were examined on the rheological and mechanical properties by partially replacing it with 0-40 wt percentage (wt. %) of Ordinary Portland Cement (OPC) in 5 wt % increments. Lifecycle of the cement-blended RCP was assessed based on cradle-to-gate confinement by evaluating the Embodied Energy (EE) and Global Warming Potential (GWP). The sustainability and economic indexes were determined at 28 days compressive strength. The active presence of calcite, silica, alumina, and ferrite in RCP enhanced the microscopic properties of the RCP Blended Cement (RCPBC) mortar. The rheology and compressive strength of RCPBC mortar increased with increasing RCP content in the mix. However, about 25 wt % of RCP replacement in the mix was optimum to attain 75% of the strength activity index. The EE and GWP of RCP BC mortar dropped by 5-34% and 85-90% at 5-40 wt % RCP substitution compared to the control mortar. A replacement level of 25 wt % RCP substitution yielded the best economic and sustainable scores. Ultimately, RCP has demonstrated a sustainable material and the findings can help achieve cleaner production, environmental protection, and sustainability.