Viscoelastic and chemical properties of wood subjected to cement alkaline environment

Wood and natural fibers degrade in the cement alkaline environment—this causes durability concerns when combining lignocellulosic materials and cement. Wood is a viscoelastic material and creeps. In this work, we focus on the changes in the viscoelastic, physical, and chemical properties of wood, and their relationships in the alkaline environment at normal and elevated temperatures that occur during the cement hydration process. We used the dynamic mechanical thermal analyzer (DMTA) and the time–temperature superposition principle (TTSP) to measure the viscoelastic properties and build master curves to predict the long-term performance of the lignocellulosic material. Fourier Transform Infrared Spectroscopy (FTIR) and Ion Chromatography (IC) were used for the chemical analysis. The alkaline environment caused mass and volume loss. We found that at the temperature of 50 °C, the mass and the volume rates of change were about three times those at 20 °C. The mass and the volume decreased at about the same rate for temperatures and treatment times. The mass loss was caused by the hydrolysis and the dissolution of hemicelluloses and lignin from the cell walls. The loss modulus (E′′) showed a linear trend with the frequency rate of the storage modulus (E′FR); The storage modulus (E′) showed a linear trend with density. At 20 and 50 °C, the E′′ and E′FR increased with the treatment time.