A recent study has introduced a fully coupled thermo-fluid–solid finite element model to more accurately predict temperature distribution and cracking risk in mass-reinforced concrete structures.
Study: Study on air-pipe cooling effect and cooling strategy of mass reinforced concrete wall. Image Credit: Francesco Scatena/Shutterstock.com
Published in Scientific Reports, the research explores how heat transfer at the concrete–pipe–air interface can be optimized to improve cooling efficiency and structural durability.
Background
Mass concrete is essential for constructing large and complex structures such as dams, high-rise foundations, tanks, and bridges. However, these massive pours often face challenges related to heat generation during cement hydration, which can cause thermal stress, internal cracking, and long-term durability issues.
The problem becomes more pronounced when steel reinforcement is used. Steel has a much higher stiffness than concrete, leading to stress concentration at the interface and increasing the likelihood of cracking.
To mitigate these risks, engineers typically use techniques like low-heat cement mixes, precooling, surface insulation, and post-cooling methods—particularly pipe-based systems that help regulate internal temperatures after pouring. While numerical models such as FE simulations are often used to study these systems, fully integrated heat–fluid–solid models remain relatively underexplored.
This study addresses that gap by developing and validating a comprehensive FE model to simulate air-pipe cooling in reinforced concrete walls, with a focus on temperature control and crack prevention.
Methods
The experiment involved a full-scale concrete wall designed to replicate real-world conditions. The test specimen measured 7200 × 3600 × 800 mm and included reinforced concrete foundations and end columns to simulate structural stiffness beyond the test section.
The wall was constructed using C50 concrete with a cement content of 415 kg/m3. To evaluate mechanical strength, 150 mm cubic samples were prepared and cured under the same conditions, with compressive strength tested 28 days after pouring. The thermal properties of the concrete were also characterized.
Ten cooling pipes were embedded within the wall at 250 mm intervals. Horizontal rebars were spaced at 200 mm, while vertical rebars were placed at 400 mm. Columns at both ends featured longitudinal rebars spaced at 100 mm. The wall was cast using plywood molds embedded with wood and steel tubes to guide the cooling system.
Immediately after pouring, air-pipe cooling was initiated and maintained for 72 hours. Platinum resistance temperature sensors were placed throughout the structure to monitor temperature changes in the concrete, air inlet, and outlet. This data was then used to calibrate and validate a numerical simulation built in COMSOL Multiphysics 6.2.
Results and Discussion
Sensor readings showed a sharp rise in temperature shortly after pouring, followed by a gradual decline—driven initially by the intense heat of hydration and later by the cooling system. However, the area near the foundation, which lacked prestressed reinforcement, exhibited insufficient cooling. This region consistently recorded higher temperatures than the rest of the wall.
At around 1.26 hours after casting, temperatures near the foundation peaked at 46.43 °C. Temperature distribution along the cooling pipes was mostly linear, except near the pipe ends, where some variation was observed. This consistent gradient produced similar temperature-time curves along different pipe sections.
As expected, the hydration process drove an initial temperature increase. After approximately 20 hours, as hydration slowed due to water consumption, the temperature began to fall. Time-temperature curves showed that the coolest zones were near the pipes and the wall surface, confirming the localized effectiveness of air-pipe cooling.
When comparing experimental data with the simulation results, minor discrepancies were noted—mainly due to ambient temperature fluctuations. A smoothing algorithm was applied to the test data, significantly improving alignment with the FE model and confirming its reliability for simulating real-world conditions.
Conclusion
This study confirms that air-pipe cooling is a practical and effective method for controlling temperature rise and minimizing thermal cracking in mass-reinforced concrete walls. By developing and validating a fully coupled thermo-fluid–solid FE model, the researchers gained a detailed understanding of how key design parameters—such as wall thickness, pipe spacing, airflow rate, and pipe layout—directly impact cooling performance.
One of the most important findings is that cooling should begin immediately after pouring and continue for at least 24 hours when working with 800 mm-thick walls. Any delay or early shutdown significantly increases peak temperatures and the likelihood of cracking. For thicker walls or slower-setting concrete, even longer cooling durations are needed to maintain structural integrity.
These insights offer engineers a data-driven foundation for designing more reliable and efficient cooling strategies in large-scale concrete construction.
Journal Reference
Yan, F., Luo, Z., Geng, Y., & Li, X. (2025). Study on air-pipe cooling effect and cooling strategy of mass reinforced concrete wall. Scientific Reports, 15(1). DOI: 10.1038/s41598-025-87033-4, https://www.nature.com/articles/s41598-025-87033-4
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