Effect of a waterproof agent on gypsum particleboard properties

This paper describes the influence of the addition of an organosilicon waterproof agent on the properties of gypsum particleboard (GPB). Test results showed that the additive at an appropriate concentration reduces the thickness swelling (TS) and water absorption (WA), and increases the mechanical properties. TS was lowered to ∼1.6% and internal bond strength (IB) was increased to ∼0.4 MPa when 3% organosilicon agent was added. Accordingly, the TS was reduced by 53% and the IB increased by 45% relative to control board without additives. The modulus of rupture (MOR) and modulus of elasticity (MOE) were also increased in the presence of the organosilicon waterproof agent. The effect was pronounced for MOR. On the other hand, too high a content of organosilicon additive had a negative effect and the corresponding property values were poorer. X-Ray diffraction revealed that the content of gypsum dihydrate increased in the presence of the additive, but other chemical changes were not observed. Scanning electron microscopy (SEM) confirmed that the crystal size in gypsum was reduced is the presence of the additive.