Fly ash and slag cement slurry containing microencapsulated phase change materials: Characterization and application

Abstract

Based on the low hydration heat and temperature rise requirements of cement slurry used in natural gas hydrate layer, two novel microencapsulated phase change materials (MPCM-1 and MPCM-2) with different melting point were designed and synthesized; then, the heat evolution of cement slurry was controlled by MPCM-1 and MPCM-2 through physical means; the decomposition of hydrates was avoided. Before synthesizing MPCM-1 and MPCM-2, the micromorphology, particle size, and distribution of paraffin wax emulsion were studied. Then, the MPCM-1 and MPCM-2 containing paraffin wax with urea formaldehyde resin shell was synthesized by in situ polymerization, and the chemical structure and performances were investigated. The melting point of MPCM-1 and MPCM-1 is 23.09°C and 35.85°C; the phase change enthalpy is 97.49 and 85.69 J/g. The MPCM-1 and MPCM-2 were added into cement slurry, and the controlling effects on heat evolution were studied. As a result, it was found that the hydration heat and temperature rise of cement slurry were successfully reduced by using MCPM-1 and MPCM-2. Simultaneously, the investigations of fly ash and slag cement slurry were accomplished. Moreover, the fly ash and slag cement slurry containing microencapsulated phase change materials was prepared. It was shown that the 24 and 48-hour hydration heat were reduced by 1.10 × 105 and 10.5 × 105 J, respectively.