## 5 Conclusions  
(1) As MR contains a large amount of Mg(OH)\({}_{2}\), when the calcination temperature was less than 800 \({}^{\circ}\)C, its setting time was less than 3 min; hence, SLMKPC samples could not be obtained at a too fast reaction speed. When the reaction between raw materials occurred at a temperature greater than 900 \({}^{\circ}\)C, strong SLMKPC samples were obtained.  
(2) W/C ratios had strong effects on the condensation time, hydration exothermic temperature, and compressive strength of SLMKPC. The setting time increased from 7 min to 12 min with the increase of W/C from 0.2 to 0.4. The exothermic hydration peak temperature first increased and then decreased, and the number of exothermic peaks gradually changed from one to two. The compressive strength of SLMKPC first increased and then decreased with the increase of W/C, and the optimal compressive strength was obtained when W/C = 0.25.  
(3) The SLMKPC system without any retarder had a longer setting time than the MPC system without any retarder. When W/C > 0.2, the setting time reached more than 7 min. In order to convert a large amount of MR into applicable SLMKPC, the setting time corresponding to W/C = 0.2-0.3 should be considered.  
(4) With the increase of W/C, the morphology and structure of hydration products in SLMKPC gradually became loose and the number of cracks simultaneously increased. When W/C = 0.2-0.3, hydrated products of SLMKPC had a high degree of crystallization and a regular columnar arrangement and the matrix had a dense structure with few microcracks.  
(5) B\({}^{3+}\) ions played a retarding role in the SLMKPC system. The content of Mg\({}_{3}\)B\({}_{2}\)O\({}_{6}\) in SLMKPC after 28 d of curing was higher than that after 3 d. It indicates that B\({}^{3+}\) ions involved in the deposition of magnesia grains in SLMKPC were released slowly with the increasing curing time.  
(6) The main hydration product of SLMKPC at different ages was MKP. The compressive strength differences of different W/C samples after 3 d and 28 d of curing were \(\Delta_{\text{W/C = 0.2}}=1.7\) MPa, \(\Delta_{\text{W/C = 0.25}}=3.1\) MPa, \(\Delta_{\text{W/C = 0.35}}=2.1\) MPa, \(\Delta_{\text{W/C = 0.35}}=20.4\) MPa, and \(\Delta_{\text{W/C = 0.4}}=10.6\) MPa (\(\Delta_{\text{W/C = 0.2}}<\Delta_{\text{W/C = 0.3}}<\Delta_{\text{W/C = 0.25}}<\Delta_{\text{W/C = 0.4}}<\Delta_{\text{W/C = 0.35}}\)). The SLMKPC systems with W/C = 0.2 and 0.3 were more stable than those with W/C = 0.25, 0.35, and 0.4. Therefore, MR calcined at 1000 \({}^{\circ}\)C could produce excellent SLMKPC with a compact structure, a certain operating space, and better mechanical properties when W/C = 0.3.  
All authors discussed and agreed upon the idea, and made scientific contributions: writing--original draft preparation, W.Z. and X.X.; experiment designing, J.W.; experiment performing, C.C.; data analysis, W.Z.; writing--review and editing, W.Z. and J.D. All authors have read and agreed to the published version of the manuscript.  
The authors would like to acknowledge the financial support from the Fund of Applied Basic Research Project of Qinghai Province, China (2020-ZJ-746, 2021-ZJ-750); The Major Science and Technology Projects of Xining City, China (2019-Z-08); The Youth Innovation Promotion Association of Chinese Academy of Sciences (2019423) and the High-end Innovative Talents Thousand Talents Than of Qinghai Province, China.  
Not applicable.  
Data Availability Statement: No new data were created or analyzed in this study. Data sharing is not applicable to this article.