## 7 Conclusions  
The eco-friendliness of GGBFS-blended concrete derives from a reduction of the carbon-intensive Portland clinker content in concrete with no detrimental affection of the microstructure development. The pore refinement by GGBFS enhances concrete durability, and therefore also indirectly the eco-performance. The synergy between GGBFS and limestone powder allows further reduction of the clinker factor in the binder system. Concrete samples with Portland cement, GGBFS and limestone powder were analysed by multicycle MIP. The considerations regarding the intrudable volume, pore entry size distribution and surface multifractal dimension led to the following conclusions:  
* The ink-bottle pores are filled during the first intrusion. The subsequent cycles showed no residual increments of the cumulated volume. Once the ink-bottle pores are filled, the process becomes fully reversible (i.e., second and third cycles are almost the same). Such reversibility suggests that the structure remains the same during the second and third cycles.
* The hysteresis in MIP is almost completely explained by the presence of ink-bottle pores (only applicable to the first cycle) and a different contact angle for intrusion and retraction.
* No influence of ink-bottle pores on the \"critical pore entry size\" was noted. The ink-bottle pores can be characterised concerning only their volume. The pore size distribution does not apply to ink-bottle pores. Thus, the first cycle is not reliable for assessing the reversibly intrudable porosity.
* GGBFS contributes to pore refinement, mostly noticed by reductions in the intrudable pore volume. Reductions in the critical pore entry size were also noted with the use of 35 wt.% GGBFS, but this second effect was less significant.
* The surface fractal dimension was successfully determined from MIP data. This can be considered as a direct statistical measurement of the pore wall texture. The actual pore surface cannot be reconstructed, but it can be modelled.
* No clear correlation between the mix compositions and the surface fractal dimension was determined. This is probably due to the dilution effect that aggregates produce in the concrete samples. The analysis of pastes might show more significant differences, but the dilution effect of aggregates and the corresponding interfacial transition zone should be addressed when upscaling interpretations.  
Conceptualisation, Y.V.-Z.; methodology, Y.V.-Z.; investigation, Y.V.-Z. and N.A.; writing--original draft preparation, Y.V.-Z.; writing--review and editing, N.A., P.V.d.H. and N.D.B.; supervision, N.D.B.; funding acquisition, Y.V.-Z. and N.D.B. All authors have read and agreed to the published version of the manuscript.  
This research was funded by ANPCyT, PICT 2017 0091 Prest BID, and Research Foundation-Flanders (FWO-Vlaanderen): MSCA-SoE 12 ZZD21N LV ([PERSON]), 12 ZGS20N ([PERSON]) and G062720N ([PERSON]).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.