Process for partial delignification and filling of a lignocellulosic material, and composite material structure able to be obtained by this process

A treatment process for treating a structure of lignocellulosic material, comprising:

• (a) soaking the structure of lignocellulosic material with at least one fluid to dissolve at least 40% and at most 85% by weight % of the lignin present in the material;
• (b) washing the structure resulting from (a) with at least one fluid so as to discharge the dissolved lignin, so as to produce a partially delignified structure;
• (c) filling the partially delignified structure with at least one filling compound, so as to produce a filled partially delignified structure;
• and
• (d) finishing the filled partially delignified structure, so as to obtain a composite material structure formed of a three-dimensional network of transformed filling compound incorporated in a network of cellulose and lignin.