# Study About the Influence of Diatoms on the Durability of Monumental Limestone
## 3 Results and Discussions  
### Open-Porosity Test Results  
The mass of water absorbed by the samples at each time interval is calculated as the difference between the mass of the sample at that interval and its initial dry mass. The mass of water absorbed by the samples between each 24 h interval corresponds to the difference between the mass at a given interval and the mass at the previous interval. It was observed that sample D3 presented a large open crack on one of its lateral faces. Due to this crack, the open-porosity level of the D3 sample was expected to be significantly higher than that of the other two diatom samples (D1 and D2). In addition, when the D3 sample was submerged in water at the beginning of the test, small air bubbles could be seen continuously escaping from the crack. From the average values shown in Figure 13, it can be verified that the samples with diatoms absorbed more water than the control samples during the first two 24 h intervals, with a greater difference in the first interval than in the second. After this initial phase, the diatom samples slowed their absorption rate. In each subsequent 24 h interval, they absorbed less water than the control samples, although in a very similar manner. Nevertheless, this did not prevent the diatom samples from maintaining a higher total water absorption overall. Analyzing the average values, it can be observed that the samples with diatoms absorbed more water throughout the test. Finally, after 240 h of immersion, the diatom samples absorbed an average of 11.35 g of water, while the control samples absorbed 9.87 g. Therefore, the diatom samples absorbed on average 1.48 g more water than the controls. Once the values for the mass of water absorbed at each time interval from the start of the test had been analyzed, the behavior of the samples between each 24 h interval could also be assessed. From the average values, the open porosity of the samples with diatoms is 0.97% higher than that of the control samples, as shown in Table 3. This may be due to the chemical weathering process caused by water acting on the limestone rock samples during their immersion in the pond for diatom treatment. Figure 13: Average mass of water absorbed in the porosity test. Similarly, Table 4 shows the open pore volume in the diatom samples to be also greater. Once again, the value for sample D3 was excluded from the average. On average, the open pore volume of the samples with diatoms increases by 1.48 mL compared with that of the control samples. This result was expected since, as abovementioned, the samples with diatoms absorbed an average of 1.48 g more water than the control samples at the end of the test. These additional 1.48 g of water were stored in the 1.48 mL of additional open pore volume present in the diatom samples. Because the density of water is very close to 1 g/mL, the results were expected to be similar. Regarding the apparent volume, which considers the volume of open pores as part of the total sample volume, all samples present similar dimensions. As shown in Table 5, no significant variation in this value was observed between the diatom and control samples. The results of the test show that the samples with diatoms present greater open porosity than the control samples. This implies that the diatom-treated samples experienced an increase in open pore volume and were able to be filled with a greater amount of water, and more quickly, compared with the control samples. In addition, it can be observed that the apparent volume of the diatom samples is practically identical to that of the control samples. This confirms that the increase in water absorption and absorption rate in the diatom samples is not due to a larger overall volume that would allow them to hold more water for that reason alone. Since this test involves total immersion of the samples in water, it allows us to determine the open porosity values of the entire sample, rather than those of specific surfaces.