Wood veneer strips as reinforcement for cement-bonded particleboards

Abstract

ABSTRACT High resistance against moisture, fire, and biodegradation is typical for cement-bonded particleboards (CBPB). However, the mechanical properties of these materials are rather low compared to other wood-based panels, despite the high density. This study deals with a new approach to increase the bending properties of CBPB with a novel reinforcement produced from veneers. Veneer strips were produced from Norway spruce and beech, each in veneer thicknesses of 1.4 and 2.4 mm. These veneer strips were placed near the surface of the CBPB during mat forming without any pre-treatment. Bending properties of the reinforced CBPB were tested after 24 h (only spruce) and 28 days (spruce and beech) of curing. Both the modulus of rupture (MOR) and elasticity (MOE) were significantly increased after 24 h due to the reinforcement as compared to the non-reinforced reference. By increasing thickness and content of the veneer strips the effect was enhanced. However, for spruce, after 28 days no significant differences between the reinforced and the reference CBPB were detectable anymore. Beech veneer strips even led to a pronounced decrease of the MOR. Instrumented analyses revealed that the reason for this missing reinforcement effect has primarily been an inhibition of cement hydration due to the alkali-activated degradation products from the veneer strips.