The natural variability and moisture sensitivity of bamboo limit its widespread use in construction applications. To address these challenges, densification and delignification processes have emerged as promising modification techniques. Densification and delignification processes can lead to significant improvements in the physical, mechanical, and chemical properties of solid wood. In this study, a two-step process of delignification and densification was carried out on Dendrocalamus asper bamboo specimens. The objective was to assess whether the optimized parameters of densification for natural bamboo on an open pressing system can be transferred for delignified bamboo. Delignification was achieved using an alkali solution (NaOH and Na₂SO₃) with two different temperature settings (25 °C or 100 °C). The pre-treated samples were dried in one of the two different conditions, either at 100 °C for 24 h or 25 °C for 30 days, resulting in four different groups with an average moisture content ranging from 7 to 10%. The samples were densified to 50% of their original thickness through an open thermo-mechanical press system at 160 °C with a compression rate of 6.7 mm/min and compared to densified bamboo without delignification (reference). The compression stress required to achieve a 50% degree of densification was evaluated, with untreated samples exhibiting an average value close to 17 MPa. Following treatment, the compression stress ranged from 7 to 13.4 MPa, indicating that the exposure to a high pH solution facilitates the densification process. However, a reduction in flexural properties (MOR, LOP, and MOE) was observed on the alkali-treated samples after a three-point bending test. Physical properties (water absorption and thickness swelling) were not altered after delignification. These findings demonstrate that the direct application of a densification process optimized for natural bamboo is not fully effective for chemically modified bamboo, highlighting the need for adjustments. Delignified bamboo showed an increase in free space after chemical treatment, which should be further densified under higher degrees.

In this study, a two-step process of delignification and densification was carried out on Dendrocalamus Asper bamboo specimens. It is aimed to investigate the densification properties of the bamboo samples after removing the lignin. To delignify the samples, two different approaches were applied. The first group was treated in a room-temperature NaOH + NaSO3 solution, while the second group was treated in the same solution at 100 ^oC. Afterward, the samples were dried in either an oven with 100 ^oC or at room temperature of 25 ^oC. Hence, a total of four different groups of delignified and dried samples were produced with an average moisture content of 7 - 10 %. The samples were then densified to 50 % of their original thickness having the thickness reduction determined a priori using a thermo-mechanical press system at 160 ^oC. The results indicated that all alkali treated samples required a lower load for the densification process compared to the reference. Average compression stress of 17.0 MPa for the reference, 10.3 MPa for the samples treated with alkali solution at room temperature, and 7 MPa for the boiled alkali solution treated samples were applied to achieve a densification degree of 50%. The drying process also affected the compression resistance of bamboo and oven-dried specimens showed an increase of 30% and 17% for room temperature and boiling temperature treatment respectively. The modulus of rupture, limit of proportionality, and elastic modulus of densified bamboo were all negatively impacted by the pre-treatment, according to the results of the bending test. Overall, untreated and treated bamboo displayed similar behavior for physical attributes in densified samples. After being treated with alkaline solution, bamboo showed reduced levels of lignin as well as hemicellulose and cellulose, according to chemical tests. In conclusion although the treatment facilitates the densification process, the time employed for the treatment and the final properties of the material did not prove to be advantageous