*2.4. Porosity and Density Measurements*

The dimensions, bulk volume (vb), and dry weight (wd) of the prepared samples were measured directly. For measuring weight and dimensions, a digital balance with 0.1 mg precision and a highly precise caliper sensitive to 0.01 mm were used, respectively. Then, the bulk density (ρb) was estimated.

The grain density (ρg) of the studied samples was measured using a helium pycnometer at the ambient conditions. Then, the helium porosity (∅He) was estimated considering the bulk and grain densities, as follows [32–34]:

$$
\heartsuit\_{\text{He}}\left(\%\right) = 100 \times \left(\wp\_{\text{\%}} - \wp\_{\text{\%}}\right) / \wp\_{\text{\%}}\tag{1}
$$

Density measurements were taken five times for each sample, and the average value was calculated.
