Influence of aerogel as aggregate in the properties of cement mortars

Abstract

In the present work, natural aggregates were replaced in a percentage of 50% by weight by grains of aerogel of the same granulometry. The aim was to record the mechanical, physical and thermal properties achieved in comparison to the reference mortar. Aerogel is a synthetic porous, light, solid material, 98% of which is air. The mean diameter of the included pores is 20nm. The pores are filled with air, which cannot move, adding exceptional thermal properties. It is a very light material (density 120-150Kg/m3) with grain size 0-2mm. The presence of aerogel resulted in low flexural and compressive strength (50% and 35% reduction respectively) in comparison to the reference. Thermal camera was used to record the thermal properties. In the modified mortars, higher resistance to heat transfer was recorded. The porous nature of the aerogel grains explain the higher shrinkage recorded during the first 28days and the high values of open porosity of the specimens while water absorption by capillarity was low due to the fact that the existing pores do not form a net but they are isolated. In conclusion, adding aerogel grains in mortars can assist the thermal behavior but the mechanical properties are reduced. For special application where high strength is not required but thermal problems need to be solved it seems that aerogel is a promising material.