A review of grout materials in geothermal energy applications

Ground heat exchangers are surrounded by grout material, making it one of the most important components in geothermal energy applications since significantly affects system's thermal performance. The current study reviews different types materials and compares their thermophysical properties. critical parameter is grout's conductivity which always presents a proportional relation with efficiency. Numerous factors involved this review to ascertain theier impact on grouts’ performance such as flowability, shrinkage, moisture content, freezing, capacity, strength, permeability, solubility imbalance. grouts compared bentonite, cement, sand, graphite, controlled low-strength dolomite, phase change materials. literature shows that best choices grouting they can provide high storage stability temperature uniformity. major problem low conductivity. Thus, recommended use composite enhance increase storage/retrieval rate.