Abstract
Fire retardant impregnated wood (FRW) was tested for moisture absorbency in high moisture condition. Fire retardant chemicals were two commercial phosphoric acid types and mixture of phosphoric acid type and boric acid type. The effect of chemical type, chemical retention and exposure relative humidity upon the moisture absorbency of FRW was investigated. And chemical's efflorescence of FRW was presumed from the amount of chemical dissolving drops occurred on surface of specimens during test. Maximum moisture absorption was affected by chemical type, and increased with increasing exposure relative humidity. Among the same chemical type, maximum moisture absorption of specimen increased with chemical retention, and their relationship was linear. The amount of drops on the surface of specimen was affected by chemical type, and increased with chemical retention and exposure relative humidity. Specimen that observed larger amount of drop, tended to show higher maximum adsorption. We concluded that chemical's efflorescence of FRW was related to moisture absorbency, and affected by chemical type, chemical retention and exposure relative humidity.
