Stabilization of Sodium Silicate with Polyacrylate in Wood Concerning Fire Resistance

Abstract

Abstract Any effects of polyacrylate on sodium silicate stabilization, improvement of fire resistance as well as physical and mechanical properties of fir wood (Abies sp.) was investigated in the current research work. Impregnation of the wood samples was done using a vacuum-pressure method. The samples were prepared according to the related standards methods and then they were impregnated with sodium silicate (concentration of 60%; S60) and polyacrylate (concentration of 50%; Pa50) as sole and mixed ones with different ratios (S60:Pa50 ratios as 2:1 and 1:2) under a vacuum of 0.5 bar for 30 minutes and a pressure of 6 bar for 3 hours. After impregnation, weight gain percentage (WPG), leaching, water absorption, volumetric swelling, anti-swelling efficiency (ASE), FTIR spectroscopy, impact load strength as well as fire resistance were determined in the treated samples. The results revealed that using polyacrylate reduced sodium silicate leaching from wood. While, sodium silicate treated wood samples showed sever leaching problem (> 16%). The least the leaching occurred in polyacrylate treated samples (almost 2%). Any presence of the polyacrylate in mixed treatments reduced the leaching; up to 10% for S60-Pa50- (2:1) and 8% for S60-Pa50- (1:2). Similarly, swelling was reduced in the samples due to addition of polyacrylate. However, ASE was reversely increased up to 39.80% and 30.10% in S60-Pa50- (1:2) and S60-Pa50- (2:1) after soaking in water for 144 hours. Any combination of the sodium silicate and polyacrylate provided proper fire resistance of the samples versus the polyacrylate treated samples. Those samples treated with sodium silicate the best protection against fire. However, the high the leaching of the sodium silicate was sever limiting problem. The impact load resistance was increased in the samples treated with a mixed sodium silicate and polyacrylate due to presence of the sodium silicate.