Synergistic modulation of thermo-mechanical properties in gypsum-based self-leveling mortar using inorganic-shell microcapsules phase change materials Chang Chen a,* , Sijia Hou a , Yanxin Chen a , Feifei Peng a , Shaowu Jiu a , Qiang Song a , Yan Liu b a College of Materials Science and Engineering, Xi’an University of Architecture and Technology, Xi’an, Shaanxi, 710055, China b State Key Laboratory of Green Building, Xi’an University of Architecture and Technology, Xi’an, Shaanxi, 710055, China A R T I C L E INFO Keywords: Inorganic-shell microencapsulated phase change materials Gypsum-based self-leveling mortar mechanical properties Phase change enthalpy Thermal conductivity ABSTRACT To overcome the inherent limitations of gypsum-based self-leveling mortars (GSMs) in floor heating applications, specifically high porosity and inadequate thermal regulation capacity, high- performance GSMs were developed by incorporating two innovative inorganic-shell micro- encapsulated phase change materials (MPCMs): octadecane@SiO 2 and sodium acetate trihydrate- urea@SiO 2 . The systematic investigation elucidates the correlation between MPCM content and thermo-mechanical properties in GSMs. Experimental results reveal that increasing MPCMs content significantly reduces the flowability of GSMs (decreases of 22.8 % for octadecane@SiO 2 - GSMs and 15.9 % for sodium acetate trihydrate-urea@SiO 2 -GSMs), while the setting time exhibits a non-linear trend: decreasing initially and then increasing. Appropriate MPCMs incorporation enhances mechanical properties via a physical filling effect: GSM with 1.5 wt% octadecane@SiO 2 and GSM with 2.0 wt% sodium acetate trihydrate-urea@SiO 2 specimens achieved flexural/ compressive strength increases of 37.1 %/17.6 % and 54.1 %/30.1 %, respectively. Microstruc- tural characterization verified that MPCMs form stable interfaces with the matrix through van der Waals forces. However, excessive content (octadecane@SiO 2 -GSMs >2.0 wt%, sodium acetate trihydrate-urea@SiO 2 -GSMs >3.0 wt%) induces agglomeration defects, leading to performance degradation. Thermal analysis demonstrates that sodium acetate trihydrate-urea@SiO 2 -GSMs, benefiting from the higher phase change enthalpy of sodium acetate trihydrate-urea@SiO 2 (286.80 J/g), exhibit optimal temperature regulation balance at 2.0 wt% content, showing a surface temperature difference reduction of 6.5 ◦ C during heating and an increase of 4.4 ◦ C during cooling compared to the control group. This study reveals how MPCMs dispersion, pore structure, and interfacial bonding work together, providing a theoretical basis for developing novel energy- efficient building materials with high thermal storage efficiency and structural stability. 1. Introduction Global energy consumption surged by > 50 % between 2000 and 2025 [1]. Buildings represent approximately 40 % of global energy demand and 39 % of energy-related carbon emissions worldwide [2–4]. Notably, operational phases account for nearly 80 % of * Corresponding author. E-mail address: changchen420@xauat.edu.cn (C. Chen). Contents lists available at ScienceDirect Journal of Building Engineering journal homepage: www.elsevier.com/locate/jobe https://doi.org/10.1016/j.jobe.2025.114220 Received 31 July 2025; Received in revised form 13 September 2025; Accepted 27 September 2025 Journal of Building Engineering 113 (2025) 114220 Available online 29 September 2025 2352-7102/© 2025 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.