EFFECTS OF CHEMICAL ADDITIVE CONCENTRATIONS ON STRENGTH AND SORPTION OF CEMENT-BONDED BOARD
Keywords:Board density, cement-wood ratio, Nauclea diderrichii
The influence of chemical additive concentration on the strength and sorption properties of cement-bonded boards (CBBs) produced from Nauclea diderrichii wood flakes was investigated. CBBs were made at three chemical additive concentrations: 1, 2 and 3% calcium chloride by weight of cement; three
nominal board densities: 950, 1150 and 1250 kg m-3 and two cement-wood ratios: 1.5:1 and 2.5:1 (weight to weight basis). The modulus of rupture (MOR) and modulus of elasticity (MOE) values increased with increased chemical additive concentration. However, increase in chemical additive concentration caused reduction in water absorption (WA) and thickness swelling (TS) after 24-hours of water soaking. MOR and MOE increased while WA and TS decreased with increase in board density and cement-wood ratio. All the CBBs produced in this study meet British standard requirements for the flexural MOE property and TS performance in the presence of water. However, only the CBBs produced using chemical additive concentrations of 2 and 3% at both 1.5:1 and 2.5:1 of cement-wood ratio satisfy the British requirement.