石墨对混凝土导热系数及抗压强度影响规律分析

能源桩兼顾承载和换热两项功能,如何在保障桩体承载力的前提下,增强其导热性能,是提高浅层地热利用效率的关键。在混凝土中添加具有良好导热性能的石墨,测试不同石墨掺量下混凝土的工作性能、力学性能和导热系数,分析石墨对混凝土性能的影响规律。结果表明:添加石墨使混凝土的坍落度、抗压强度持续降低,导热系数逐渐升高,石墨掺量体积分数为5%时的混凝土配合比,可兼顾导热性能与承载力两项指标。采用VHX5000超景深显微镜对石墨混凝土的细观结构进行观察,发现随着石墨体积分数的增大,细骨料中石墨粉之间排列紧密形成连续的导热通道,使得热量快速传递,从而在宏观上提高混凝土的导热系数。

Analysis of the Influence of Graphite on the Thermal Conductivity and Compressive Strength of Concrete

Energy piles take into account both the bearing and heat transfer functions. How to enhance the thermal conductivity of the piles under the premise of ensuring the bearing capacity of the piles is the key to improving the efficiency of shallow geothermal utilization. Adding graphite with good thermal conductivity to concrete, testing the working performance, mechanical properties and thermal conductivity with different graphite content, and analyzing the influence of graphite on concrete performance. The results show that the addition of graphite makes the slump and compressive strength of concrete continue to decrease, the thermal conductivity increases gradually, and the concrete mix ratio when the volume fraction of graphite is 5% can take into account the thermal conductivity and bearing capacity. The microstructure of graphite concrete was observed by VHX5000 ultra-depth microscope. It was found that as the volume fraction of graphite increased, the graphite powder in the fine aggregate was closely arranged to form a continuous heat conduction channel. This enables rapid heat transfer, which increases the thermal conductivity of concrete at a macroscopic level.