Hydration and Microstructure Evolution of Acrylamide-Modified Tunnel Slag Mortar Under Various Curing Conditions.

Tunnel slag mortar (TSM) is gaining attention as a sustainable construction material due to its potential for resource efficiency. Prior research has shown that tunnel slag can be effectively utilized in mortar production, reducing the need for conventional cement. However, TSM is prone to cracking during service, which limits its application in critical structural contexts. Acrylamide (AM) modification has been proposed as a method to improve the mechanical performance of TSM. Yet, the effects of AM on hydration behavior and microstructure remain unclear. This gap motivated researchers to explore how AM influences hydration kinetics and pore structure. No prior work had resolved the impact of curing temperature and humidity on AM-modified TSM. Understanding these factors is essential for developing optimal curing strategies. The current study addresses this uncertainty by analyzing hydration and microstructural evolution. The findings may help refine the use of AM in sustainable construction materials.

This study aimed to investigate how acrylamide (AM) modification affects the hydration behavior and microstructure of tunnel slag mortar (TSM) under different curing conditions. The specific problem addressed was the lack of understanding about how AM influences hydration kinetics and pore structure in TSM. The motivation for this work stems from the need to optimize TSM’s performance in construction applications. By varying curing temperature and humidity, researchers sought to determine the optimal conditions for AM-modified TSM. The study also aimed to assess the sensitivity of AM-modified TSM to environmental factors. This information could inform the development of sustainable construction materials. The results may guide the selection of AM dosages and curing regimes in practical applications. The study’s findings may help improve the durability and mechanical properties of TSM.

Researchers used low-field nuclear magnetic resonance (LF-NMR) to track hydration kinetics in AM-modified tunnel slag mortar (TSM). X-ray diffraction (XRD) was employed to identify hydration products and assess their evolution. Scanning electron microscopy (SEM) provided insights into micromorphology and pore structure changes. The study involved modifying TSM with varying dosages of acrylamide (AM) and subjecting samples to different curing conditions. Curing temperature was varied between 20 °C and 60 °C to assess thermal effects. Curing humidity was also controlled to determine its influence on hydration and pore refinement. The experimental design allowed for a systematic comparison of AM-modified TSM under diverse environmental conditions. These methods enabled a comprehensive analysis of hydration behavior and microstructural evolution.

The results showed that AM incorporation delayed early hydration in tunnel slag mortar (TSM) but did not change the types of hydration products. Increasing the curing temperature partially counteracted the retarding effect of AM. At 40–60 °C, a 3% AM dosage enhanced hydration more effectively than lower dosages. Pore refinement was found to be highly dependent on environmental conditions. At 20 °C, a 3% AM dosage produced optimal pore refinement. However, high temperatures led to pore coarsening instead of refinement. AM-modified TSM showed greater sensitivity to curing humidity compared to conventional TSM. Adequate moisture was identified as a critical factor for optimizing pore structure. These findings suggest that curing conditions must be carefully controlled when using AM-modified TSM.

The study concludes that acrylamide (AM) modification affects the hydration kinetics of tunnel slag mortar (TSM) but does not alter hydration product types. The retarding effect of AM is mitigated at higher curing temperatures, especially at 40–60 °C with a 3% AM dosage. Pore refinement in AM-modified TSM is strongly influenced by environmental factors. At 20 °C, a 3% AM dosage yields optimal pore refinement, but high temperatures lead to pore coarsening. AM-modified TSM is more sensitive to curing humidity than conventional TSM. These findings suggest that curing conditions must be carefully selected to optimize performance. The study highlights the importance of controlling moisture levels during curing. The results may help guide the application of AM-modified TSM in construction.