Effect of Cement Substitute Produced From Sustainable Materials on the Setting Time of the Mortar

Present research is aimed at reducing the carbon footprint of Portland cement, which contributes to global warming. Its objective is to produce concrete made from sustainable, eco‐friendly materials (slag and lime dust) that have properties similar to cement and provide a double benefit by reducing waste in landfills and reducing cement pollution. The current research aims to implement pozzolana as a partial replacement for cement (0%, 100%, 5%, 7.5%, and 10%) with the adaptation of a special type of superplasticizer to reduce the setting time and enhance the strength. Ten concrete mixes containing slag and lime dust in different proportions were used as a substitution for cement. Tests of setting time, compressive strength, and dry density were applied. Results revealed that the initial setting time lies between 50 and 180 min, whereas the final setting time ranges between 4 and 17 h. Superplasticizer Sika ViscoCreet‐171 is used to accelerate the setting time; the highest compressive strength is recorded for Mix 1 (100% cement), followed by Mix 5 (10% cement). The shortest initial setting time (50 min) was recorded for Mix 1 with superplasticizer, whereas the longest final setting time (17 h) was recorded for Mix 2. An SEM‐EDS (scanning electron microscope—energy‐dispersive x‐ray fluorescence spectroscopy) technique clarified the microstructural behavior of the used mixes. In conclusion, the materials used to substitute for cement showed promising results that may open the horizon for the use of sustainable pozzolanic materials in the concrete industry.