Physico-mechanical, thermal properties and durability of foamed geopolymer concrete containing cenospheres

In this study, cenospheres (CP, a lightweight component) was used to replace part of fly ash (FA) to prepare ultra lightweight foamed geopolymer concrete (UFGC), and the fresh properties of the geopolymer paste was used to control the hardening performance of the UFGC sample. The results show that incorporating CP to the slag-FA system can effectively reduce the reaction rate of the geopolymer paste and increase its fluidity and setting time. Meanwhile, as the CP content increases, the density of the geopolymer foams decreases, and it exhibits better mechanical properties and thermal insulation performance when the substitution ratio of CP is 50%. In addition, a proper amount of CP improves the pore structure of the UFGC sample, reduces its sorptivity coefficient and drying shrinkage deformation. Therefore, a novel building exterior wall insulation material is prepared through CP to optimize the UFGC system, and its (C50) thermal conductivity is reduced by 37.86% compared to the control group, which is beneficial to the development of green and sustainable buildings.