Innovative mortars containing nanofibrillated cellulose (NFC) and basic oxygen furnace slag (BOFS): optimizing ultrasonication methods for higher eco-efficiency

Incorporating waste materials into cementitious composites is a promising practice for enhancing the sustainability of the construction industry. However, previous papers have not explored the combination of nanofibrillated cellulose (NFC) with basic oxygen furnace slag (BOFS) for producing eco-efficient mortars, nor have they examined the optimization of NFC dispersion within these matrices. To narrow these research gaps, this paper presents an experimental program for the design of innovative mortars containing both NFC and BOFS, based on the optimization of ultrasonication procedures for improvement of eco-efficiency indicators. Ultraviolet–visible (UV–vis) spectroscopy, zeta potential analysis, and scanning electron microscopy (SEM) were used to evaluate the dispersion and stability of NFC solutions prepared with different sonication times (0.00, 0.04, 0.08, 0.16, and 0.32 min/ml). Mortars containing BOFS and these different types of NFC solutions were subjected to tests for determination of workability, compressive strength, flexural strength, eco-efficiency indicators, X-ray diffraction (XRD) and SEM analyses. Results indicated improved NFC dispersion and stability through sonication, leading to enhanced mechanical performance and eco-efficiency indicators. The most favorable results were observed in mortars with NFC sonication times of 0.04 and 0.16 min/ml, showcasing performance gains of 17.9 % and 13.4 % compared to the reference specimen, respectively. In conclusion, optimizing ultrasonication methods can be a highly effective strategy for enhancing the eco-efficiency performance of novel mortars containing BOFS and NFC. • First study focused on production of cementitious composites with BOFS and unbleached NFC. • Sonication promotes gains in flexural strength of cementitious composites with BOFS. • Sonication improves the eco-efficiency of nanomodified cementitious composites. • Use of BOFS and unbleached NFC for sustainable civil construction is a promising alternative. • Sonication times of 0.04 and 0.16 min/ml enabled performance gains of 17.9 % and 13.4 %, respectively.