Experimental study on the performance of phase change energy storage concrete for energy piles based on Gum Arabic and PEG-600

To produce phase change energy storage concrete, phase change materials (PCM) can be encapsulated and mixed into concrete. Phase change energy storage concrete energy piles demonstrate higher heat transfer efficiency than conventional ones. Concrete strength decreased by replacing coarse aggregates with phase change aggregates. Gum Arabic (GA) can enhance the strength of concrete and is more economical and environmentally friendly than mineral admixtures. This research manufactured PCM-HSB aggregates by encapsulating hollow steel balls (HSB) with polyethylene glycol 600 (PEG-600). GA is selected as an admixture to enhance the strength of concrete. The mechanical and thermal characteristics of GA-PEG-HSB concrete were tested at various GA admixtures (0.7%, 0.9%, 1.1%, 1.3%), and PCM-HSB replacement rates (15.0%, 17.5%, 20.0%). Determination of concrete characteristics by compressive strength, thermal conductivity, specific heat capacity, and Coefficient of thermal expansion (CTE). The test evidence shows that the PCM-HSB replacement rate has a negative correlation with the thermal conductivity of concrete but a positive correlation with the specific heat capacity. The compressive strength of the concrete was affected by GA, and the peak compressive strength of the concrete was reached at 0.9% dosage. The optimal ratio of GA-PEG-HSB concrete is water: cement: fine aggregate: coarse aggregate: PCM-HSB: GA=210: 500: 633: 842: 157: 1.89. The optimal replacement rate of the PCM-HSB is 20 %, and the optimal dosage of the GA is 0.9 %. The experimental results show that the mechanical and thermal properties of GA and PEG-600 phase change energy storage concrete are superior and meet the future development needs of energy pile technology.