Microstructure and macroscopic properties of LC3 cementitious composites incorporating perforated cenosphere-encapsulated phase change materials

초록

This study presents a novel composite strategy to introduce perforated cenospheres encapsulated with phase change material (CenoPCM) into a limestone-calcined clay cement (LC3) system, with the goal of constructing a multifunctional cement-based material with both low-carbon properties and thermal regulation capabilities. The effects of CenoPCM on the hydration behavior, microstructure, and macroscopic properties were systematically investigated using multiscale testing methods, including isothermal calorimetry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DTG), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The results show that the introduction of the CenoPCM significantly reduces early strength; the 1-day compressive strength of the PCM6.4 sample decreased from 22.65 MPa to approximately 8.06 MPa (a reduction of approximately 64.41%), while the 28-day strength reached 57.85 MPa, which is within the applicable range. The calorimetric results show that the PCM system exhibits a significant hydration delay phenomenon, manifested as a delayed early exothermic peak and a reduction in the cumulative exothermic heat. The thermal performance test results revealed that the phase transformation effect of the PCM reduced the peak temperature of the sample by approximately 4 degrees C and slowed the temperature change process. The microscopic analysis results indicated that the CenoPCM did not introduce significantly new reaction products into the LC3 system; its main effects were effective dilution of the cementitious material, localized hydration delay, and alteration of the interfacial structure rather than direct participation in chemical reactions. This study innovatively introduces the CenoPCM, a component of the cementitious system, into the LC3 system, revealing its multiscale coupling influence mechanism in terms of the hydration behavior, interfacial structure, and macroscopic properties. This study demonstrates that synergistic thermal regulation and engineering performance effects can be achieved in a low-carbon LC3 system, providing new insights for the design of functionalized low-carbon cement-based materials.

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