Effect of Metakaolin Addition on The Mechanical Performance and Durability of Granulated Blast Furnace Slag Based Geopolymer Mortar with Micro-Encapsulated Phase Change Materials

Incorporating microcapsule phase change materials (MPCM) into geopolymer is one of the most successful solutions for enhancing building thermal comfort and replacing Portland cement-based materials. Although MPCM improves the thermal capacity of the cementitious matrix, whether it's made of cement or geopolymer, it presents a number of disadvantages in terms of mechanical and physical performance. Several researchers have pointed out that this scientific subject remains unresolved. The purpose of this study is to investigate the influence of 10% and 20% metakaolin (MK) inclusions on the mechanical properties and durability of geopolymer-MPCM mortars based on granulated blast furnace slag (GBFS) and to compare them with Portland cement-MPCM based mortars. The results show that the addition of two proportions of metakaolin is able to compensate well for the loss of mechanical strength associated with the addition of MPCM. Thus, up to 20% MPCM, the addition of metakaolin increases compressive strength by approximately 10 MPA. Compared to Portland-MPCM cement mortars, all geopolymer-MPCM mortars show higher compressive strength, better workability and lower porosity. Finally, in terms of durability evaluation, the resistivity measurements reveal that the risk of corrosion of the cement-based mortar on the steel bars is negligible, while the risk of corrosion of the geopolymer-based mortar on the steel bars is low.