In this paper, novel geopolymer-coated expanded clay-phase change material (GP-L-PCM) macrocapsules added to geopolymer concrete (GPC) with volume ratios of 25%, 50%, and 75% for the production of GP-L-PCM slabs are described. The same amounts of lightweight expanded clay aggregate (LECA) were used to develop LECA slabs. The thermal and structural performances of LECA and GP-L-PCM slabs were compared with a reference GPC slab. It was observed that LECA and GP-L-PCM slabs exhibit lower heat transmission, represented by lower maximum surface temperatures (a decrease of 5.6 degrees C and 8.0 degrees C on the back surface) than that of GPC slab. Accordingly, the LECA and GP-L-PCM slabs exhibit U-values of 1.6 and 0.9W/m(2)K, respectively, with 75% addition of LECA and GP-L-PCM capsules compared to 2 W/m(2)K for GPC. Substantial decrease in compressive strength was observed in the LECA and GP-L-PCM slabs as compared to GPC for all tested samples. (C) 2019 Elsevier B.V. All rights reserved.