Thermomechanical properties of a new small-scale reinforced concrete thermo-active pile for centrifuge testing

The use of thermo-active geo-structures has been recognised to be a sustainable engineering solution that can reduce carbon emissions from civil infrastructure. Physical modelling in a geotechnical centrifuge has been increasingly used to study the behaviour of this kind of geo-structures and their interaction with the surrounding soil under cyclic heating/cooling loads. Previous studies have been limited by the choice of materials used to model thermo-active geo-structures (such as aluminium and conventional concrete), due to inaccurate scaling of the thermal properties and the inability to capture the quasi-brittleness and strength properties of reinforced concrete (RC) due to improper scaling of aggregate sizes. The paper aims to develop a new thermally-enhanced plaster-based model concrete which can realistically reproduce both the thermal and mechanical properties that are representative of concrete at prototype scale. The new model concrete, combined with steel wire reinforcement (i.e. geometrically scaled reinforcing bars and stirrups), was then used to create 1:20 scaled RC thermo-active piles. Effects of temperature on their thermomechanical behaviour, including the coefficient of thermal expansion, moment capacity and flexural stiffness, were investigated. The suitability of using the newly-developed RC thermo-active piles for future centrifuge testing is discussed.