Figure 18.
Thermal macro-cracks on part of the geopolymer concrete specimen cross-section at (a) 800 °C and (b) 1000 °C (Note: GPH-H, Mix proportions: 1201 kg m−3 coarse crushed basalt aggregate, 539 kg m−3 natural siliceous sand, 460 kg m−3 fly ash, 150 kg m−3 sodium silicate, 50 kg m−3 sodium hydroxide, 3-sodium-silicate-to-sodium-hydroxide ratio, sodium hydroxide solution molarity of 14, 80 °C curing temperature, and 5.21% water content; 200×, 200× magnification; 1000×, 1000× magnification). Reproduced with permission from [22], [Construction and Building Materials]; published by [Elsevier], [2020].