what is cross laminated timber? The advantages of cross laminated timber

What is cross-laminated lumber?

Cross-laminated lumber is a factory prefabricated engineered wood that is made of at least 3 layers of solid wood or composite plywood vertically and orthogonally, and then pressed with adhesive. It has strong mechanical properties because it makes full use of the wood properties of high tensile strength along the grain direction and high compressive strength along the grain direction in the processing technology. Cross-laminated lumber is particularly suitable for plywood construction.


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What are the advantages of cross-laminated lumber?

(1) High strength, good bearing capacity and high dimensional stability. Due to the orthogonal structure between adjacent layers, the cross-laminated lumber has high strength in both the main and sub-directions of the material, which can prevent the connectors from splitting.

(2) Factory prefabricated and assembled on site. Cross-laminated lumber can be prefabricated in the factory and assembled on site, with fast assembly speed and low noise, which can not only speed up the project progress, but also ensure product quality, and promote the development of site-specific wood structure buildings.

(3) The utilization rate of wood is high. The cross-laminated lumber realizes the "good use of inferior wood, and great use of small wood". The main wood used in cross-laminated wood includes douglas fir, larch, spruce, pine, boxwood, etc, and some fast-growing wood can also be used as the lumber of cross-laminated wood.

(4) Good shock resistance, sound insulation and heat preservation effect. cross-laminated lumber has excellent functionality, outstanding thermal insulation and sound insulation effects, and is also used in areas where earthquakes frequently occur.

(5) Green and environmental protection. Cross-laminated lumber uses biomass material, which has the function of carbon sequestration, and can be recycled after dismantling.


Cross-laminated timber production process

The production process of cross-laminated lumber generally includes the following steps: lumber selection, lumber grading, lumber surface processing, lumber sawing, sizing, billet assembly, pressing, post-processing, packaging and transportation.

The sawn plywood must be dried before production. Drying can reduce the moisture content of the wood to a certain extent. Appropriate moisture content can help to obtain good gluing performance and dimensional stability, and prevent the sawn plywood from warping. It is necessary to ensure that the sawn plywood moisture content of the wood is close to about 12%, and the difference in moisture content between adjacent layers should be less than 5%.

Sizing on the surface of sawn timber is a very important part. The surface quality of sawn timber has a great influence on the quality of sizing. It is necessary to shorten the time between the surface processing of sawn timber and the sizing process. Due to the large size of the cross-laminated lumber, the surface is suitable for mechanical gluing, and the gluing speed should be set according to the adhesive.

The blanks of the cross-laminated timber should be laid perpendicular to each other on the adjacent two layers, and consist of a certain number of sawn timbers. The blanking time should not exceed the aging time of the adhesive.

The pressing of cross-laminated timber is divided into ordinary hydraulic pressure and vacuum pressing. Due to the small vacuum pressure during vacuum pressurization, a stress relief seam is often cut along the length of the sawn timber to reduce the deformation of the sawn timber.

The pressed cross-laminated timber should be sanded on the surface, and then the window openings and joints should be sawed according to the requirements of the building.



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