Influence of perlite and aerogel addition on the performance of cement-based mortars at elevated temperatures

Structures confront severe damages when subjected to fire, related to the characteristics of the fire (i.e. maximum temperature, duration) and the constructional types and materials confronted. During the last decades, the influence of fire and extreme temperatures on building materials has been induced. In this paper, the influence of perlite and aerogel addition on the resistance of cement-based mortars at elevated temperatures is studied. Four compositions of cement-mortars have been manufactured and tested at 200°C, 400°C, 600°C, 800°C and 1000°C. The mortar mixtures was based on cement I42.5 and siliceous sand (0-4mm) in a Binder/Aggregate ratio of 1/2. A proportion of 20% w/w of aggregates was substituted by perlite, while an addition of aerogel at a proportion of 0.5% w/w of binders was performed. After their exposure at the elevated temperatures, the physico-mechanical properties of the specimens were recorded, concerning: volume change, weight loss, porosity, apparent specific gravity, dynamic modulus of elasticity, flexural and compressive strength. Additionally, macroscopic and microstructural observation was conducted. From the comparative evaluation of the results it was concluded that although the perlite and aerogel addition, reduced the initial strength of the mortar compositions, they had a positive effect on their resistance at elevated temperatures, especially regarding their volume stability and mechanical properties above 800°C.