Lightweight reinforced wood beams through compression of its surface layers combined with the removal of lignin and hemicellulose

When wood is used as a stressed component of building materials, the parts most prone to failure are the upper and lower surfaces which can be called the weak structure. In a hydrothermal environment, lignin and hemicellulose in wood readily soften and dissolve, thus leading to their designation as the weak structure. The weak structures results in the wood having a low strength. In this paper, the sandwich beam material can be obtained by removing two steps from the top-down method, whereby the weak structure of the wood surface was removed by the alkaline mixed solution, and then the wood surface was densified. The authenticity of the sandwich structure is proved by a scanning electron microscope (SEM) and density profile analysis. When the moisture content (MC) is 10 %–12 % and the mass loss ratio is 23.04 %, the optimal resilience of the sandwich beam is only 1 %, the maximum modulus of rupture (MOR) and modulus of elasticity (MOE) are 1.42 and 2.1 times greater than those of natural wood, respectively. This finding shows that our method strengthens the weak structure of natural wood, which has good flexural performance and springback ratio.