The aims of this study were to impregnate polyethylene glycol (PEG) 4000 in low-cost silica fume (SF) to form phase change material (PCM) composites with cementitious value, and to provide a quick -fix design for PCM (1) with tailor-made thermal properties and behaviors by particle blending of two types of polyethylene (PEG)/silica fume (SF) composites having different PEG wt% loading, and (2) with enhanced physical properties by turning the powdery PEG/SF composites into round granules through spherical agglomeration. The simple composite blending method was used to broaden and tune the application temperatures in response to variable conditions and environments without the need of searching for new materials to mitigate global warming. Spherical agglomerates of PEG/SF composite exhibited a good homogeneity in thermal properties and low Carr's indices indicating of excellent flowability, packability and compactibility, and offering an enhanced contact area for heat transfer and uniform mixing with other building materials. Noticeably, the agglomerates displayed higher heat capacity values of solid phase, C-ps, and liquid phase, C-pl, than those of the composite determined by temperature -history method. The thermal stability of PEG75/SF composites was also attested by the small enthalpy loss, and the highly reproducible melting and solidification behaviors after more than 100 temperature cycles. (C) 2017 Elsevier Ltd. All rights reserved.