Study On Processing Technology Of Strengthened LVL From Plantation Chinese Fir

Laminated veneer lumber (LVL) has been developed rapidly in developed countries and it has been abroad used in building and bridge in recent years. But the production of LVL is small and the products quality of LVL can not meet the international standard, there is great chance for the development of LVL in China. As a wood-based composite, LVL is a high performance building material, which in performance of achieves greater strength with smaller weight, stiffness, and mechanics stability from a timber resource than solid lumber. LVL application in public building with a long span is broad in the future.This paper focuses on the Chinese Fir veneer enhancement, dyeing, strength and physical ability to meet the actual situation of research and application of Chinese Fir and LVL. This paper deals with the manufacturing technology of strengthened laminated veneer lumber (LVL) from plantation Chinese fir. This strengthened LVL is manufactured using Chinese Fir veneer, impregnated with modified water-soluble UF resin. The effecting factors on modulus of elasticity (MOE) and modulus of rupture (MOR) of strengthened LVL, such as, impregnating process,dry-temperature, compression ratio, hot-pressing temperature and hot-pressing time were studied. The results indicated that the five factors all had effect on the physical properties of the LVL. Compression ratio and mass increasing ratio were the two dominant variables both affecting LVL MOE and MOR. Besides, High dry temperature of the veneer after impregnated with modified water-soluble UF resin could harden before hot-pressing progress. Therefore, temperature under 70℃is suitable. As far as the pressing time and temperature, separately 1.2-1.6 min/mm and 140℃were suitable. After dyeing of the veneer, the range of this kind LVL application extended, and the result of best dyeing process was 50℃, under 0.8 MPa persisting 20min.