Cement, Energy and Environment

24 positive effect on strength gain for the dosage of 2.5 % to 7.5 %. Beyond that, some negative effects appear which cause the decrease in CS. This result exactly reflects the trend of CS that appeared for the mortar cubes (Table 3, Fig. 5). Hence GEOFS can be considered as a potential supplementary cementitious material as well as a performance enhancer for PSC cement making, to provide enhanced compressive strength by addition in an optimized dosage (2.5 to 7.5 % w.r.t total cement). 4.0 CONCLUSIONS This experimental work has explored EOF slag as a value-added, potential supplementary cementitious material, which was almost untouched from the aspect of utilization so far. Mineralogical and microstructural analyses using different advanced analytical techniques have found that EOF slag is rich in minerals and has significant potential to be recycled. The optical polarizing microscopy and XRD analysis have revealed that the material is highly crystalline. Moreover, the qualitative XRD analysis has shown that there are some common cementitious crystalline phases of EOF slag and Portland cement clinker like di-calcium silicate and tri- calcium silicate. There is another crystalline phase named Zeolite, which shows good pozzolanic behavior for cement hydration. The developed blended cement with a 2.5 to 7.5 % addition of GEOFS has demonstrated significant improvement in compressive strength for both mortar and concrete applications, compared to the control sample (PSC 1, without GEOFS). The Figure 7: Compressive Strength Vs Curing time plot of concrete cubes of blended cement. heat of hydration determination by the isothermal calorimetry technique has proven the existence of additional reactivity of GEOFS in cement hydration. Hence it is believed that this present work will enlighten a new route of application of a steel plant waste material(EOF Slag) to make a value- added material like cement. This is a potentially sustainable approach from the aspect of waste management as well as circular economy. NOMENCLATURE EOF Energy optimization Furnace SCM Supplimentary Cementitious Material PSC Portland Slag Cement OPC Ordinary Portland Cement GEOFS Ground EOF Slag XRD X-Ray Diffraction C2S Dicalcium Silicate C3S Tricalcium Silicate C3A Tricalcium Aluminate C4AF Tetracalciumaluminoferrate REFERENCES 1. F. de Souza and S. R. Bragança, Thermogravimetric analysis of limestones with different contents of MgO and microstructural characterization in oxy-combustion, Thermochimica Acta, 561(2013), p. 19. 2. T. Hanein, F. P. Glasser and M. N. Bannerman, Thermodynamic data for cement clinker, Cement and Concrete Research, 132(2020), p. 106043. 3. Concrete needs to lose its colossal carbon footprint, Nature, 597(2021), p. 593-594, doi: https://doi.org/10.1038/d41586-021-02612-5. 4. P.-C. Aïtcin, Supplementary cementitious materials and blended cements, Science and Technology of Concrete Admixtures, (2016), p. 53. 5. Indian Minerals Yearbook 2018, Part-II, Metals and Alloys, 57th Addition, Slag-Iron and Steel. (2018), p. 16, https://ibm.gov.in/writereaddata/ files/02182020101538Slag_Iron_Steel_2018.pdf. 6. Y.K. Sabapathy, V.B. Balasubramanian, N. S. Shankari, A. Y. Kumar and D. Ravichandar, Experimental investigation of surface modified EOF steel slag as coarse aggregate in concrete, Journal of King Saud University – Engineering