Polyurethane bonded cross-laminated timber prepared from Pinus radiata

Abstract

The utilization of cross-laminated timber (CLT) in the multi-storey construction sector has been increasing over the last two decades. To effectively bring these new materials into the mainstream construction market, reliable information is needed on physical and mechanical behaviour of such composites. Further, destructive testing is not always possible and depends only on limited samples. Hence, deriving material properties by non-destructive means can be very helpful. Similarly, predicting the properties of a composite from the properties of its constituent material derived by non-destructive testing can save time, material and money. However, the accuracy of prediction is very important as it influence the decision of the structural engineer/architects. In this endeavour, the present study reports the physical and mechanical properties of polyurethane bonded cross-laminated timber prepared from radiata pine wood. Acoustic-based non-destructive test was carried out to determine the dynamic modulus of elasticity (DMOE) of individual planks as well as individual layers. Based on the dynamic MOE of individual lamella, the MOE of CLT was predicted using the rule of mixture and the predicated MOE was validated by measuring the actual MOE of the CLT by destructive testing. Although the flexural modulus and compressive strength of radiata pine CLT are lower than that of Norway spruce, a timber commercially used in the production of CLT, the superior bonding performance, as evident from the lower delamination and higher bond shear strength, suggests the potential of radiata pine in CLT production for light frame construction. The MOE predicted through the rule of mixture was quite comparable to the MOE derived by destructive testing.