**4. Conclusions**

In this study, we obtained and studied the properties of magnesium phosphate and calcium magnesium phosphate cements based on calcined magnesite and calcined dolomite (at different temperatures) with/without sand addition and potassium dihydrogen phosphate.

The following conclusions can be drawn:

• The thermal treatment of dolomite at 1200 ◦C and 1400 ◦C leads to the decomposition of calcium magnesium carbonate into CaO and MgO. The increase in calcination temperature, from 1200 to 1400 ◦C reduces the reactivity of calcium and magnesium oxides vs. water or phosphate (MKP) solution; for the phosphate cements based on dolomite calcined at 1200 ◦C, an important increase in paste temperature during the setting and paste's expansion was noticed due to the high reactivity of oxides (CaO and MgO); the increase of thermal treatment temperature at 1400 ◦C determines a decrease of the oxides' reactivity, and for a higher KH2PO4 dosage (corresponding to D14/KH2PO4 = 2 weight ratio), the pastes have measurable compressive strength at early ages. Nevertheless, for all specimens based on dolomite calcined at 1400 ◦C, the compressive strengths dramatically decrease after 7 days of hardening, which is most probably due to a delayed hydration of CaO and MgO.


**Author Contributions:** Conceptualization, C.A.V. and A.B.; Investigation, C.A.V., A.I.N.; G.V.; Methodology: C.A.V. and A.B.; Supervision, A.B. and G.V.; Writing—original draft, C.A.V. and A.B.; Writing—review and editing, A.B. and G.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** Cristina Andreea Vijan acknowledges the financial support of the Operational Programme Human Capital of the Ministry of European Funds through the Financial Agreement 51668/09.07.2019, SMIS code 124705.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

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