Cross-laminated timber (CLT) became a popular engineered wood product in recent years for highquality and innovative timber buildings. As for any building product, the fire behaviour of CLT panels requires careful evaluation in the design of such buildings. The adhesive used in the bond lines of CLT plays an important role in the fire design. However, currently, European standards do not provide a test method to assess the adhesive performance in CLT exposed to fire. This paper presents a series of fire tests performed with CLT panels glued with different adhesives. It is shown how the mass loss of the CLT panels in standard fire resistance tests can be used to assess the adhesive performance in CLT exposed to fire.
The state of the art requires a closed waiting time of about one hour for the beech glulam production. This has a negative influence on the production costs. Micro structured surfaces showed good performance in combination with coatings. The authors have performed tension-shear and delaminating test in order to investigate the influence of micro structured surfaces on the bond quality of hardwoods. The results are very promising and show clearly improved delaminating resistance for all tested adhesive. No closed waiting time was needed to achieve satisfying results using MUF in combination with beech.
Cross laminated timber (CLT) has been developed to a worldwide well-known and versatile useable building material. Currently increasing rates in production volume and distribution can be observed. In fact CLT, thanks to its laminar structure making it well suited for use in construction, provides new horizons in timber engineering, in areas which had until now been the realm of mineral building materials like concrete and masonry.
After a short introduction, this paper aims to demonstrate current production processes used for rigid CLT. In section 2 the process steps are described and essential requirements, as well as pros and cons of various production techniques, are discussed. Latest results of R & D and of development and innovation in production technology are presented. In section 3 test and monitoring procedures in the area of the internal quality assurance, known as factory production control (FPC), are presented. Diverse regulations, in the form of technical approvals for CLT as well as in the CLT product standard prEN 16351 , are discussed. Additionally, some technological aspects of the product, CLT, together with a comparison of geometrical and production relevant parameters of current technical approvals in Europe are provided in section 4. In the final and main part of the paper, production and technology is presented in a condensed way. The outlook for current and future developments, as well as the ongoing establishment of the solid construction technique with CLT, is given. The product, CLT, comprises an enormous potential for timber engineering as well as for society as a whole. Standardisation and further innovation in production, prefabrication, joining technique, building physics and building construction make it possible for timber engineering to achieve worldwide success.