## 5 Conclusions  
In this study, the influence of further hydration under different humidity and temperature conditions was evaluated, along with its impacts on the mechanical properties of cement pastes. First, the effect of further hydration was studied under the following humidity conditions: sealing state, RH50% \(\pm\) 5% and RH \(\geq\) 95%, while the water-soaking condition was maintained constant at 20 \({}^{\circ}\)C. Thereafter, its impacts were evaluated under the following temperature conditions: water soaking at 40 and 60 \({}^{\circ}\)C while maintaining RH \(\geq\) 95% at 20 \({}^{\circ}\)C. Finally, a rapid evaluation mechanism for further hydration was presented. Based on the experimental results, the following conclusions can be drawn:  
1. Among the four humidity environments: sealing state at 20 \({}^{\circ}\)C, RH50% \(\pm\) 5% at 20 \({}^{\circ}\)C, RH \(\geq\) 95% at 20 \({}^{\circ}\)C, and water soaking at 20 \({}^{\circ}\)C, RH \(\geq\) 95% at 20 \({}^{\circ}\)C had the most significant improvement effect, leading to an increase in the compressive strength and flexural strengths of 22.6% and 75.2%, respectively, after further hydration for 180 d.
2. Among the three temperature environments: RH \(\geq\) 95% at 20 \({}^{\circ}\)C and water soaking at 40 and 60 \({}^{\circ}\)C, water soaking at 60 \({}^{\circ}\)C showed the most significant effect on the strength and expansion strain of the cement paste. After further hydration for 180 d, the compressive strength increased by 31.4% compared to that before further hydration, whereas the flexural strength decreased by 13.8%, and the expansion strain was 1.1 times higher than that under water-soaking conditions at 40 \({}^{\circ}\)C.
3. Considering the stability of the evaluation indices, further hydration was evaluated using the following parameters: the combined water content for further hydration, expansion strain, and compressive strength. Moreover, considering the acceleration and damaging effects of further hydration experiments, water soaking at 60 \({}^{\circ}\)C optimally accelerated further hydration.  
For HPC and UHPC structures that have been in long-term service in aqueous environments such as sea-crossing channels, offshore deepwater harbours, and large-scale sea-crossing bridges, the influence of further hydration on the properties of hardened cement pastes cannot be overlooked. This study can serve as a foundation for evaluating and designing the long-term performance of cement-based materials with low water-binder ratios. While the results of the study are valid for the range of parameters considered herein, further experiments should be conducted to support and expand the knowledge gathered in this work.  
Conceptualization, M.A.; methodology, M.A.; validation, Y.L. and Y.W.; formal analysis, Y.L.; investigation, G.Z. and Y.L.; resources, M.A.; data curation, G.Z. and Y.L.; writing--original draft preparation, Y.L.; writing--review and editing, M.A., Y.L. and Y.W.; visualization, Y.L.; supervision, M.A.; project administration, M.A.; funding acquisition, M.A. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (Grant Nos. 52278238 and 51878033).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.