**4. Conclusions**

This experimental work investigated the physical properties as well as the thermal insulation property of cement mortar containing EGA and TiO2. The findings revealed that incorporating EGA into the mortar composite causing a significant decrease in density and compressive strength, which was attributed to the porous nature and low compressive strength of EGA. The results also demonstrated that as the EGA content increased, the workability and water absorption of cement composite increased. It is found that the increase in water absorption was due to the high porosity of EGA in comparison to NA. However, the beneficial e ffect of the EGA was the decrease in the heat-transferring rate of the cement composite, which indicates the feasibility of a potential reduction in energy consumption in buildings. Moreover, the results demonstrated that inclusion of TiO2 into the cement composite partially compensated the water absorption and loss in compressive strength. However, it was revealed that addition of nTiO2 into EGA-cement composites increased the heat transfer rate of the cement matrix and insulation properties as nTiO2 acts as nanofillers and changes the pores structure in the cement matrix. It can be concluded that in terms of thermal behavior, substitution of NA with EGA decreases the heat transfer rate and consequently improves the thermal insulation properties of the cement mortar.

**Author Contributions:** Conceptualization, A.Y., W.T.; methodology, W.T., M.K., S.W. and C.F.; Investigation, W.T., M.K. and A.Y.; writing—original draft preparation, A.Y., M.K.; writing—review and editing, W.T., C.F., M.K., S.W. and A.Y. All authors have read and agree to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors gratefully acknowledge the financial support provided by University of Newcastle (2017 UNIPRS and UNRS Central Scholarship). We also thank the support and cooperation of the sta ff of the concrete laboratory at the School of Civil Engineering, University of Newcastle, and Expanded Glass Technologies Pty Ltd. for providing EGA for this experimental investigation.

**Conflicts of Interest:** The author declares no conflict of interest.
