Enhancing thermal insulation in cement mortar with silica aerogel and recycled PET plastic

Rising energy costs create a significant challenge in balancing thermal comfort for building occupants with reduced energy consumption. This research to the best of our knowledge for the first time, incorporates surface-modified silica aerogel and recycled PET plastic to develop thermal insulation cement-based mortar with favourable thermal and mechanical properties. Two mortar series were prepared; the first series contained a conventional mortar mix, with 3 %, 5 % and 7 % of untreated silica aerogels as a volume replacement to natural sand. The second mortar series were prepared by adding 3 % recycled polyethene terephthalate (PET) plastic as a volume replacement to natural sand with three thermal insulation cement mortar mixes containing surface-modified silica aerogel in order to explore the potential for sustainable construction practices. To evaluate the performance of these mortars, we investigated setting time, flow of fresh mortar, and dry bulk density. The compressive and flexural strength as well as, the thermal conductivity and microstructure were analysed here. The thermal conductivity of mortar has been reduced by up to ⁓ 55 % compared to standard mortar samples due to partial substitution of sand in mortar with hydrophobic silica aerogel powders and PET plastic. In addition, the same mortar mix satisfies the N-type masonry mortar according to (BS-EN 413–1:2011, ASTM c270–10, AS 1012/As 3700) practice code for building compressive strength as well as flexural strength and setting (initial and final) times, respectively, so it can be used as thermal insulation cement- based mortar within masonry construction, for example, to reduce thermal bridging effect. • Improved adhesion between silica aerogel particles and cement binder in mortar. • Use of recycled PET plastic in silica aerogel thermal insulation cement mortar. • Up to 55 % reduction in thermal conductivity values of mortar. • Compressive strength values of mortar and the initial and final setting times are within British standards.