# Evaluation of Early-Age Compressive Strength in Winter Prefabrication: A Comparative Study
## 4 Results and Discussion
### Calorimetric Test
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**Scenario 2**} & \multicolumn{6}{c}{**Scenario 3**} \\  & **Scenario 1** & \multicolumn{6}{c}{**Material 8 \({}^{\circ}\)C**} & \multicolumn{6}{c}{**Material 8 \({}^{\circ}\)C**} \\  & **T = 20 \({}^{\circ}\)C** & \multicolumn{6}{c}{**Water Heated 35 \({}^{\circ}\)C**} & \multicolumn{6}{c}{**Heat 35 \({}^{\circ}\)C**} \\  & & & & & & & & & **Heat 35 \({}^{\circ}\)C** \\ \cline{2-10}  & **Fi-1** & **Fii-1** & **Fiii-1** & **Fi-2** & **Fii-2** & **Fii-3** & **Fii-3** & **Fiii-3** \\ \hline Heat realized [J/g] & 328 & 325 & 241 & 210 & 215 & 82 & 380 & 388 & 310 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Summary of heat release measurements for cement samples across three curing scenarios. Figure 5: Calorimetric analysis of hydration in fi-3 cement: post-mixing heat treatment. * Scenario 3: Post-Mixing heat treatment  
Fi-3: The calorimetric profile indicates a rapid temperature increase followed by a sharp rise in heat release, suggesting a highly accelerated hydration process facilitated by post-mixing heat treatment. This is evidenced by a pronounced heat release of 380 J/g, directly correlating with a significant increase in compressive strength to 38.3 MPa. Fii-3 and Fiii-3: Also exhibit substantially higher heat releases (388 J/g and 310 J/g, respectively), indicating accelerated hydration kinetics due to elevated temperature curing. The observed compressive strengths (39.8 MPa and 30.9 MPa) highlight the potential of controlled heating to enhance both the rate and extent of cement hydration, significantly impacting mechanical performance. The comprehensive analysis intertwining calorimetric data and mechanical performance across different curing scenarios unveils profound insights into the complex nature of cement hydration and its implications for concrete technology. By meticulously examining the interaction between environmental conditions, cement chemistry, and supplementary cementing materials, we gain a polyvalent understanding of concrete comportment [27, 28, 29]. * Enhanced understanding of hydration phases  
Calorimetric profiles and mechanical data give a detailed insight into the hydration process:  
Initial Reaction Phase: The pronounced temperature rise and heat release in the initial reaction phase, especially evident in Fi-1, underscores the high reactivity of CEM I 52.2N. This rapid onset of hydration highlights the sensitivity of this phase to cement composition, setting the stage for early strength development. Dormant Period: The extended dormant period observed in Fi-2, marked by lower heat release and a flat temperature profile, illustrates how environmental conditions, specifically cold, can significantly delay the hydration process. This delay has critical implications for the curing of concrete in adverse conditions, underlining the need for appropriate curing practices. Acceleration to Steady State: The swift transition to a steady-state phase in Fi-3, facilitated by post-mixing heat treatment, demonstrates an optimized environment for continuous hydration product formation. This phase is essential for achieving high strength and durability in the early stages of aging, as it ensures a sustained reaction that contributes to the development of the microstructure [30,31]. * Correlation of heat and temperature dynamics with mechanical properties  
The analysis shows a direct correlation between the calorimetric data and the mechanical properties of the concrete [32,33]:  
Heat-Temperature Lag: The observed lag between temperature peaks and maximum heat release, particularly in Fi-1, could be indicative of the timing in the formation of critical hydration products like calcium silicate hydrate (C-S-H), which is instrumental in strength development. This lag not only reflects the kinetics of chemical reactions but also the evolving microstructure of the concrete [34].