<b>ABSTRACT</b></br>

Self-compacting structural mortars (SCSM) incorporating slags from electric steelmaking as aggregates are manufactured and tested in this study. Their design requires careful proportioning and grading of the aggregates to prevent the negative impacts of slag on mixture workability. In general, these mixes with 60% of the natural aggregates in volume substituted by the slag aggregates met in the fresh state the prescriptive conditions of current normative standards for self-compacting mixes. The internal structure of the hardened mixes, characterized by Mercury Intrusion Porosimetry (MIP) and Computerized Axial Tomography (CAT), revealed the typical features of quality mortars. Shrinkage tests at room temperature and accelerated potential expansion tests at higher temperatures were also performed on the mixtures, to evaluate their long-term dimensional stability. The mechanical properties of the mortars over time also showed good behavior in terms of both compressive and tensile strength and suitable stiffness values. Globally considered, the characteristics of these mortars manufactured with slag in both the fresh and the hardened state were satisfactory for use in masonry and construction.

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<b>ACKNOWLEDGEMENTS</b></br>

The authors wish to express their gratitude to: the Spanish Ministry MCI, AEI, EU and ERDF [RTI2018-097079-B-C31; PID2019-106635RB-I00; 10.13039/501100011033; FPU17/03374]; the Junta de Castilla y León (Regional Government) and ERDF [UIC-231, BU119P17]; Youth Employment Initiative (JCyL) and ESF [UBU05B_1274]; and the University of the Basque Country [PPGA19/61] for additional funding. Our thanks also go to the Basque Government research group [IT1314-19] and likewise to CHRYSO, Morteros y Revocos Bikain and HORMOR for supplying the materials used in this research.