Feasibility of Liquid Nitrogen Frozen Concrete as Cooling Unit for Mass Concrete: Strength Development and Interface Characteristics

Liquid nitrogen frozen concrete introduces a novel cooling method for mass concrete structures. This approach involves subjecting fluid concrete to low-temperature treatment and then strategically placing frozen concrete blocks within mass concrete to regulate the internal temperature. This process effectively reduces the internal temperature of mass concrete without the need for additional cooling materials. We conducted a study on the feasibility of using liquid nitrogen frozen blocks in the combination of mass concrete, including interface and performance control. Strength and durability tests were conducted to explore interfacial interaction issues during the cooling process, assessing key technical parameters such as compressive strength and chloride ion migration resistance. Microstructural analyses, including mercury intrusion porosimetry and scanning electron microscopy, were also performed to investigate the underlying mechanisms. The results indicate that the interfacial issues between frozen concrete and ordinary concrete are negligible. When the performance of frozen concrete is enhanced, the 28-day strength of the composite structure can be reduced by only 4.6%, while the resistance to chloride ion migration can be improved by about 20%. Frozen concrete demonstrates excellent temperature control capabilities, making it suitable for regulating the temperature of mass concrete as well as in extreme environmental conditions.