ABSTRACT
Presently, cement-bonded particleboards are manufactured in 12 countries. The total capacity is about 3,500 m3/d. The board comprises about 20 wt% of wood particles and 80 wt% of hardened portland cement. The modulus of rupture of the boards is about 8 to 10 MPa and the density is between 1,100 and 1,250 kg/m3 (Simatupang 1989). The manufacture of cement-bonded particleboards is based on the patent of Elmendorf (1966). A scheme of the industrial process is shown in Fig. 1. Suitable wood is converted to appropiate wood particles, and mixed with water containing additives and cement. The furnish is a spreadable mixture and is relatively dry, compared to cement mixtures, generally applied in concrete technology. The furnish is continuously spread on metall cauls. Subsequently it is prepressed and the cauls are stacked. On the bottom and on top of each stack, two heavy iron frames are placed. With a hydraulic press the stack is pressed to the desired height, and also to the desired board thickness. Due to the long setting time of portland cement, the stack has to be kept under pressure until the green
Abstract The manufacturing process and the properties of cement-bonded
particleboards are shortly described. It is feasible to reduce the press time from 6-8 h to 10-15 minutes, if potassium, sodium or ammonium carbonate and waterglass are added as accelerator. Properties and durability of experimental particleboards made according to the new process are presented and compared with conventionally made cementbonded boards. Feasibility and limitations of the novel process are discussed.
