Microencapsulated Phase Change Materials to Develop Functional and 3D-printable Cementitious Composites

Rising energy demands from population and economic growth necessitate reducing the 16.5% household energy consumption allocated to heating and cooling systems, and revolutionizing conventional construction. This thesis explores the feasibility, potential, and limitations of enhancing thermal performance in buildings by integrating conventional microencapsulated phase change materials (MEPCMs) into 3D-printable cementitious systems and proposes a novel approach for synthesizing cement-compatible MEPCMs.

The first part of the thesis explores the incorporation of commercially available MEPCMs into 3D-printable cementitious composites, including ordinary Portland cement-based mortars and fly ash-based geopolymer as a sustainable alternative. These investigations address the influence of MEPCMs on rheological properties essential for the 3D printing process, early-stage hardening evaluation, hardened material properties, and the thermal performance of printed structures.

The second part addresses the common challenge of mechanical strength reduction when incorporating common polymeric MEPCMs into cementitious materials. To overcome this, a novel method for synthesizing cement-compatible MEPCMs is developed using cenospheres, which constitute ~1% of coal fly ash, a byproduct of thermal power plants with an annual production of 750 million tons. The cenospheres are functionalized and sealed with silica, a cement-friendly material, and melamine-formaldehyde polymer, a widely used industrial shell, to encapsulate PCMs. This approach facilitates an in-depth investigation of the interfacial interactions between the microcapsules and the cementitious matrix, where silica sealing shows 50% better mechanical strength than MF sealing.

In summary, this thesis contributes to significant advancements in construction materials by demonstrating the potential of MEPCMs to enhance the thermal efficiency of 3D-printable cementitious composites, reducing energy consumption by up to 40%. This research also establishes a foundation for future developments in cement-compatible thermally efficient construction materials, promoting innovative strategies to reduce energy consumption and environmental impact.