The immediate and short-term degradation of the wood surface in a cement environment measured by AFM

Abstract

This study aims to measure the pit torus and border to monitor the immediate and short-term degradation of wood surfaces after the concrete is cast and the cement hydration releases heat. The surface morphology and adhesion force curves were measured by atomic force microscopy during the treatments in saturated calcium hydroxide solutions ranging from 1 h to 27 days. The results showed that the pit torus and pit border showed different degradation processes. The adhesion force was sensitive to the type of the surface chemical components exposed during the degradation, while the surface modulus, deformation and jump-off force ratio were sensitive to the surface structural strength. The surface modulus of the pit torus degraded to 0.61–0.66 of the untreated original (95% CI) after 7-h treatments, and degraded almost completely after 48-h treatments. The surface modulus of the pit border degraded to 0.83–0.95 of the untreated original (CI) after 10 days and to 0.20–0.23 of the untreated original (95% CI) after 27 days of treatments. The treatment temperature 50 °C caused a 10-times faster degradation in the torus modulus compared to the temperature 20 °C.

Unraveling lignin degradation in fibre cement via multidimensional fluorometry

“…Most studies on durability (mechanical stability) of fibre cement are based on lengthy accelerated aging experiments (e.g., wet-dry cycles), which are highly time-consuming, and taxing on labor and materials. On the contrary, spectroscopic and/or microscopic characterization techniques 14 are rapid, and non-destructive, and can provide direct evidence about the phenomena that occur at the fibre–cement interface even at the preliminary stages of curing (i.e., 7d).…”