## 3 Results
### Mercury Intrusion Porosimetry  
MIP measurements were performed on the powders 1 day and 25 days after being submerged in each of the four different exposure environments. The results of these measurements are shown in Figures 8 and 9. This analysis aimed to validate the chemical changes occurring within the samples' microstructures. The characterization focused on assessing total porosity as well as its distribution. According to the existing literature [3, 59], the pores within cement paste samples can be categorized into distinct zones:  
* Microopores or gel pores, spanning from 1 nm to around 10 nm, emerge as a result of the hydration process. These pores are influenced by factors such as the interlayer spacing of calcium hydroxide and calcium-silicate-hydrate, the type of binders employed, curing conditions, water-to-binder ratio, and the age of the specimens. * Pores ranging from 10 nm to 100 nm are referred to as small to medium capillary pores. These pores originate from water-filled spaces and are notably impacted by the \(w/b\) ratio and the degree of hydration. * Large capillary pores, spanning between 100 nm and 10 \(\upmu\)m, are water-filled and also filled due to C-S-H particle aggregation. * Macroopores have a diameter exceeding 10 \(\upmu\)m in size and typically contain entrapped air within the paste. The characteristics of these pores are influenced by the presence of additives, the \(w/b\) ratio, the workability of the mixture, and the fabrication process. Figure 7: FTIR spectra of the four mixtures after 25 days of exposure to (**a**) chloride and (**b**) sulfate-chloride. Upon analyzing the total porosity of the extracted powders after exposure, a distinct pattern emerged. Mix1, consisting solely of CEMI, exhibited the lowest porosity level in this context, ranging from 40% to 45%. In contrast, the porosity levels of the other mixes fell within the range of 55% to 65%. To gain deeper insights into the factors contributing to this rise in porosity when substituting cement with alternative binders, it is imperative to delve into the distribution of porosity across different size ranges. Examining the porosity distribution, it becomes evident that the increase primarily occurred in the macropores, attributed to entrapped air. The formation of these pores was significantly influenced by the type of additives employed, the \(w/b\) ratio, the mixture's workability, and the fabrication procedure, as previously mentioned. The choice of binders directly impacts the workability of pastes [60]. In the context of this study, where the specimens were not subjected to vibration during fabrication, the incorporation of alternative binders led to an increase in entrapped air within the mixes. Consequently, this phenomenon contributed to the observed higher porosity levels in the samples. This may suggest that the mixing procedure should not be uniform for every binder type. Figure 8: The total porosity and its distribution at both day 1 and day 25 under different exposure conditions for (**a**) Mix1, (**b**) Mix2, (**c**) Mix3, and (**d**) Mix4. A 25-day immersion in water (EXP0) increased the overall porosity due to the ongoing hydration process and the creation of hydrated compounds. A noticeable decline in pores with dimensions smaller than 10 \(\upmu\)m was obvious across all four mixes. When considering the impacts of both chloride and sulfate attacks, alterations in total porosity and its distribution are heavily contingent upon various factors, such as CH dissolution, C-S-H decalcification, AFm consumption, ettringite and gypsum formation rates, the emergence of cracks [46], and the ongoing hydration process, particularly considering the early age of the samples. Figure 8 reveals that when chloride and sulfate were present (EXP1, EXP2, and EXP3), the total porosity of cement aggregates, constituting the exposed powders, decreased after one day of exposure when compared to the ones exposed to water. This decrease was related to the formation of ettringite, gypsum, and Friedel's salt [29].