Processing of calcium sulfoaluminate eco-cement coatings containing microencapsulated phase change materials

On the one hand, calcium sulfoaluminate (CSA) eco-cements release about 40% less carbon dioxide (CO₂) than Portland cement during fabrication; on the other hand, phase change materials dispersed in a cementitious matrix can help to optimise the indoor temperature of buildings, reducing carbon dioxide emissions related to heating/air conditioning. However, this is only economically viable if it is used as a thin layer (a coating). In addition, the combination of both materials supposes a double environmental benefit. Consequently, the main objective of this work is the preparation of a suitable homogeneous and well-adhered bilayer sample, composed of CSA and CSA-MPCM. To achieve this, in the first step, the effect of pH, temperature and stirring was studied for microencapsulated phase change material (MPCM) aqueous suspensions (47.3 wt%); second, the MPCM (45 wt% with respect to dry cement) was dispersed in a CSA paste; then, in a third step, a homogeneous well-adhered coating of CSA-MPCM, with undamaged MPCM, was obtained on a CSA matrix. This was achieved through rheological measurements and checked by microscopy. Finally, the corresponding CSA and CSA-MPCM mortars were characterised through their mechanical properties (compression) (70 and 13 MPa at 7 days, respectively) and thermal conductivity (2.06 and 1.19 W/mK, respectively).