Effect of Microencapsulated Temperature Rise Inhibitor on the Temperature Rise of Medium-Sized Concrete

This study investigates the effect of microencapsulated temperature rise inhibitors (TRIs) on the hydration temperature evolution and crack resistance of medium-sized concrete structures. Unlike mass concrete, medium-sized concrete elements such as beams, slabs, and columns pose unique challenges in temperature control due to their moderate volume, limited heat dissipation, and susceptibility to thermal stress-induced cracking. To address this issue, concrete mixtures with TRI dosages of 0%, 0.05%, 0.1%, and 0.15% were evaluated using a sealed foam box method, allowing for precise monitoring of hydration temperature development under insulated conditions. The results indicate that TRIs effectively suppress peak hydration temperature and delays its occurrence, with higher TRI dosages leading to more pronounced effects. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirm that the hydration suppression is attributed to a controlled-release mechanism, where TRIs gradually dissolve, forming a hydration barrier on cement particles. This slows down calcium hydroxide (CH) crystallization, alters C-S-H gel evolution, and reduces early age heat accumulation, mitigating thermal cracking risks. Furthermore, mechanical property tests reveal that, while early age compressive and tensile strength decrease with TRI addition, long-term strength recovery is achieved at optimum TRI dosages. This study identifies 0.1% TRI as the most effective dosage, striking a balance between hydration heat reduction and long-term mechanical performance. These findings provide a scientific basis for optimizing TRI dosages in medium-sized concrete applications, offering a practical solution for thermal cracking prevention.