Influence of the Curing Temperatures on the Mechanical Properties of Hemp Fibre-Reinforced Alkali-Activated Mortars

Abstract

The aim of this research was to investigate how the curing temperature influences the mechanical properties of fibre reinforced alkali activated matrices. The mortar matrix contained fly ash as a binder, sodium water glass as an activator and sand with a particle size between 0.4 and 0.8 mm. As reinforcement hemp fibres of 10 mm in length and of volume ratio 1% of the composite were used. The prism mortars had dimension of 40 × 40 × 160 mm3 and were cured under three different temperatures: 20 °C, 60 °C and 80 °C. The results showed that after adding the fibres specimens cured at room temperature (20 °C) increased their compressive strength, flexural strength and energy absorption for 4%, 57% and 711% respectively. At the 60 °C and 80 °C curing temperatures the compressive strength of the specimens decreased for 8% and 27% respectively, whereas the flexural strength decreased for 14% in case of 60 °C curing temperature but remained the same after the curing temperature of 80 °C. The energy consumption of the specimens increased for 331% and 153% when specimens were cured at the 60 °C and 80 °C respectively.