In mass concrete structures, thermal control of cement hydration heat is essential to prevent harmful thermal cracking and long‑term durability problems. This study numerically evaluates the transient thermal performance of three embedded cooling pipe layouts—Serpentine Type 1, Serpentine Type 2, and Spiral from Center—using both water and a high‑conductivity nanofluid, and compares them against a no‑pipe Baseline condition. For water cooling, the maximum concrete core temperature decreases from 80°C in the Baseline to 60, 58, and 50°C for Serpentine Type 1, Serpentine Type 2, and Spiral from Center, corresponding to 25%, 27.5%, and 37.5% reductions in peak temperature, respectively. The maximum temperature gradient (ΔTmax) is reduced from 25°C to 18, 17, and 14°C, indicating 28%, 32%, and 44% decreases in thermal non‑uniformity and potential thermal stress. In the spiral layout, employing a nanofluid instead of water further improves performance, increasing the reduction in core temperature from 30% to 35% and the reduction in ΔTmax from 44% to about 52%. These findings highlight the superiority of the Spiral from Center configuration combined with nanofluid in managing the thermal response of mass concrete and provide practical guidance for optimizing the design of embedded cooling pipe systems in large concrete elements such as dams and massive foundations.