**4. Conclusions**

The effects of adding titanium dioxide particles and modifying the system L/S ratio on the physicomechanical and structural properties of an MK-based geopolymer were evaluated. The results indicate that the addition of titanium dioxide particles at up to 10 wt % did not affect the formation of the KASH gel and that these particles coexisted within it. The compressive strength was maximized by adding titanium dioxide particles in proportions of 5 and 10 wt % at a dry (L/S = 0.35) and an average (L/S = 0.40) consistency, respectively. No improvement in the compressive strength was found for materials with a fluid consistency (L/S = 0.45). The fluidity and the setting time of the material were affected by the addition of titanium oxide particles and the L/S ratio; adding titanium dioxide particles at 10 wt % decreased the fluidity by up to 20.27%, and the setting time decreased by up to 30.13%. In contrast, an increased L/S ratio resulted in increases in the flowability and setting time of up to 20% and 60%, respectively.

**Acknowledgments:** This study was funded by the Colombian Institute for the Development of Science, Technology, and Innovation COLCIENCIAS (project, "Construction of prototype at the scale of rural housing using innovative materials with low carbon footprint," contract 096-2016). The authors, who are members of the Composite Materials Group (GMC) from the Centre of Excellence in New Materials (CENM), would like to thanks to Universidad del Valle (Cali, Colombia), in which the experimental work was carried out.

**Author Contributions:** Mejía de Gutiérrez R. and Maury-Ramírez A. conceived and designed the experiments; Guzmán-Aponte L. performed the experiments; Guzmán-Aponte L., Mejía de Gutiérrez R. and Maury-Ramírez A. analyzed the data; Mejía de Gutiérrez R. contributed reagents/materials/analysis tools; Guzmán-Aponte L., Mejía de Gutiérrez R., and Maury-Ramírez A. wrote the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.
