Increasing Sustainability in Buildings Through Energy-Efficient Concrete

Abstract

The energy performance of buildings is influenced by a wide range of climatic and design-related variables, including but not limited to ambient temperature, heating and cooling systems, and thermal properties of building elements. This thesis explored the magnitude of the impact of the thermal properties of concrete compared to other influential factors and assessed their critical role in the energy performance of buildings. To this end, several approaches have been employed to improve the thermal performance of concrete, such as partial to full replacement of cement and natural aggregates with supplementary cementitious materials and recycled concrete aggregates, respectively, resulting in the production of lightweight concrete. However, incorporating recycled contents into concrete mixes beyond certain percentages can negatively impact the mechanical performance of concrete, which poses a challenge for engineers and designers balancing thermal, environmental, and mechanical performances. With the goal of spanning the mentioned requirements, this thesis proposed an AI-assisted framework integrating data-driven modelling techniques and multi-objective optimisation algorithms to optimise recycled aggregate concrete mixes targeting energy performance-related and economic objectives without compromising their mechanical strength.

In this sense, incorporating recycled contents and air bubbles into concrete mixes was found to be an effective approach to address some hurdles associated with concrete 3D printing, which is a promising technique for large-scale construction projects due to its speed and cost-efficiency. The results showed that increasing air voids allowed for replacing recycled content beyond commonly used percentages, resulting in lightweight and ultra-lightweight 3D printable cementitious composites with significant thermal conductivity improvements.