Early age and hardened properties of 3D printable cement-lime mortars with microencapsulated PCM and cellulose microfibers

The design of sustainable functionalized materials suitable for new building technologies has become a challenge for the construction sector. In this study, 3D printable cement-lime mortars incorporating microencapsulated phase change material (PCM) and cellulose microfibers (CMF) were designed and experimentally characterized considering the requirements for architectural applications. The use of lime aims to reduce environmental impact, PCM intends to enhance thermal performance and CMF to provide early age integrity. Two reference mortars were designed, with and without CMF, and PCM was incorporated at 10, 20 and 30% into both reference mixtures. An experimental program was carried out evaluating mortars’ fresh state rheological properties, early age performance and short- and long-term hardened-state physical, thermal and mechanical properties. Long-term carbonation was also assessed. The experimental approach provided a comprehensive understanding of how these components interact across all relevant stages of material development, from fresh state to long-term performance. Lime densified mortar matrix, due to carbonation, contributing to strength gain and reducing water absorption. PCM improved thermal behavior by enhancing their energy storage capacity up to a 35 – 40%, while CMF mitigated early age setting delays in mixtures containing PCM but reduced the thermal storage enhancement at PCM contents above 20%.