Effects of microencapsulated phase change material on physico-mechanical and thermoregulation performance of lightweight geopolymer concrete with zeolite and perlite

This study examines impact of microencapsulated phase change material (MPCM) additives on physical and mechanical characteristics of geopolymers produced using natural zeolite and slaked lime. The binder composition consists of 90 % zeolite and 10 % slaked lime, activated with NaOH at a Na/binder ratio of 14 % by weight. Basalt-based sand and perlite were used as aggregates with a water/binder ratio of 0.60. MPCM was added in varying proportions of 8 %, 16 %, and 24 % relative to the binder weight. Samples were molded in dimensions of 50 × 50 × 50 mm and 200 × 200 × 20 mm, then cured at 95 °C for 24 h. Differential Scanning Calorimetry (DSC) outcomes presented that geopolymer composite with MPCM has a melting degree of 26.45 °C and a melting enthalpy of 17.8 J/g. Fourier Transform Infrared Spectroscopy (FTIR) results confirmed physical integration of MPCM into geopolymer structure. The study also evaluated compressive strength, ultrasound pulse velocity (UPV), dry unit weight, and microstructural properties using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Thermoregulation performance experiments demonstrated that the MPCM-enhanced samples effectively moderated temperature fluctuations, maintaining lower temperatures for controlled heating and higher temperatures for natural cooling phases compared to the control sample. Thermal regulation capabilities of MPCM-infused geopolymers were evidenced by their property of absorbing and releasing heat, which is critical for energy-efficient building materials. Additionally, the durability and stability of the geopolymer matrix were enhanced by the uniform dispersion of MPCMs, which also improved the composite's mechanical performance. The successful integration of MPCMs highlights their potential in developing sustainable construction materials that contribute to energy savings and environmental conservation.