## 4 Conclusions  
Three samples of ornamental stone sawmill granite sawdust have been studied. They were siliceous rocks with quartz, biotite, kaolinite, amorphous material, and feldspars (albite and orthoclase). The particle sizes were between 5 \(\upmu\)m and 9.5 \(\upmu\)m.  
Natural samples have been tested for pozzolanicity tests. After one year of cement reaction, and follow-up at 1, 7, 28, 90, 180, and 360 days, all of the samples showed pozzolanic activity, with higher values of pozzolanic activity for grey granite sawdust waste. This waste content was a large amorphous material concentration.  
When 10% waste was added to the OPC, the same compounds were produced as if they were cement, without substitution, and coexisting with the initial minerals in the waste (quartz, feldspar, mica, kaolinite, and hematite). When 20% was added, the processes were similar to that mentioned for 10%, in terms of the hydration products obtained, and those inherited from the initial composition. C-S-H gels and LDH compounds appeared in large quantities. In the samples with substitution, portlandite concentration decreased in medium times and remained in long.  
Shortest setting times corresponded to the residue additions with the highest percentage related to the particle size and amorphous material present; therefore, it took the least time to set.  
The shrinkage values that have been measured were directly proportional to time, with the smallest values for 20% substitution after one year, the percentage of addition did  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Cycles (Number)** & **Without Addition** & **10\% Addition** & **20\% Addition** \\ \hline
0 & 10.15 & 13.23 & 12.96 \\
64 & 17.12 & 15.32 & 11.53 \\
92 & 19.21 & 15.30 & 15.22 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Total porosity of mortars (%) exposed to gelifraction cycles.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Without Addition** & **10\% Addition** & **20\% Addition** \\ \hline crack failure & 30 & 64 & 82 \\
60\% threshold & 35 & 86 & 110 \\ mean & 32.5 & 75 & 95 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Number of cycles before failure occurs.  
not influence the shrinkage, and all of the waste was equal in behavior. The volumetric stability showed a slight increase in the expansion of the pastes with an addition of 10%, but the values obtained in the additions and samples were within the standard.  
The flexural strength for all wastes and for all additions was less than the OPC. Lower results coincided with short cure times, but equalized over time. The compressive strength increased in all waste and substitutions, stabilizing in the year.  
Total porosity and average size of the pores in the mortars with addition were modified with respect to the OPC. There was a decrease in porosity from 0.001 to 0.09-mm\({}^{3}\) of the mortars with substitutions of 10% and 20%. The most abundant pore volume was greater than 0.09 mm\({}^{3}\), keeping its number constant throughout the hydration reaction. Medium-sized pores were reduced in number, from 10% addition and with 20% addition; larger pores were almost non-existent.  
Mortars made with 10% and 20% waste substitutions have a higher durability in terms of gelifraction processes, compared to mortars without addition.  
S.Y. formal analysis; C.G.-G.: validation; V.R.-P.: conceptualization; A.S.-L.: investigation. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
We thank Granitos Cardenosa, Avila (Spain) for the possibility of collecting samples at their facilities for this study.  
The authors declare no conflict of interest.