A new model concrete for reduced-scale model tests of energy geo-structures

Concrete energy geo-structures such as piles and diaphragm walls exhibit complex thermomechanical behaviour and interaction with the surrounding soil. Small-scale physical model tests including the use of geotechnical centrifuges have been utilised to study such soil-structure interaction. However, existing materials used to model concrete energy geo-structures do not simultaneously scale both the mechanical and thermal properties. This study attempts to develop a new material that could have representative thermal and mechanical behaviour of concrete. The new material is a plaster-based mortar with the addition of fine copper powder. It is revealed that adding copper powder from 0 to 6% (by volume) to the mortar resulted in a 90% increase in thermal conductivity. More importantly, such an addition was not found to cause significant increase or reduction of the mechanical strength, including both the unconfined compressive strength and modulus of rupture. These findings suggest that while the thermal properties of concrete can be properly scaled, the new type of mortar can maintain its ability to also correctly scale the mechanical behaviour of concrete simultaneously. This will allow the study of a range of geotechnical problems, where thermal properties and structural strength are important, such as slope reinforcement using concrete energy piles.