PHYSICAL AND MECHANICAL PROPERTIES OF BAMBOO (Bambusa vulgaris) BASED CEMENT-BONDED COMPOSITES AS INFLUENCED BY PRODUCTION VARIABLES

Abstract

Cement Bonded Composites were produced from the mixture of Bambusa vulgaris (Bamboo) particles and inorganic binder. The study investigated the influence of Board Density (BD), Mixing Ratio (MR) and Curing Reagent Concentrations (CRC) on the behaviour of bamboo bonded composites. The effects of three levels of Board Density (1000 kg/m3, 1100 kg/m3 and 1200kg/m3), three levels of cement/particle Mixing Ratio (1.5:1, 2.5:1 and 3.5:1) and three levels of Curing Reagent Concentrations (1.5 %, 2.5 % and 3.5 %) were assessed. The experimental design was a 3 x 3 x 3 factorial experiment in a Completely Randomized Design (CRD) which gave 27 treatment combinations of experimental boards. Properties assessed include Water Absorption (WA), Thickness Swelling (TS), Modulus of Rupture (MOR), Modulus of Elasticity (MOE), Energy at Break (EB) and Accelerated Aging (AA). The Cost Benefit Analysis (CBA) of the boards was also determined. Data obtained were subjected to Analysis of Variance, Correlation and Multiple Regression analyses. The Water Absorption (WA) and Thickness Swelling (TS) properties decreased as the Board Density, Mixing Ratio and Curing Reagent Concentration increased. The Water Absorption values ranged from 3.40 % to 17.84 %, while the Thickness Swelling values ranged from 0.11 % to 0.73 % after 24hr immersion. The Modulus of Rupture, Modulus of Elasticity and Energy at Break increased as the Board Density, Mixing Ratio and Curing Reagent Concentration increased. The Modulus of Rupture ranged from 2.29 N/mm2 to 9.04 N/mm2 while Modulus of Elasticity ranged from 747 N/mm2 to 4573 N/mm2 and Energy at break ranged from 0.065 Nm to 0.261 Nm. The study shows increase in BD, MR and CRC caused decrease in dimensional movement and increase in the strength of boards. Similarly, Water Absorption and Thickness Swelling properties decreased as the Board Density, Mixing Ratio and Curing Reagent Concentration increased after accelerated aging. The Water Absorption values ranged from 6.33 % to 20.90 %, while the Thickness Swelling values ranged from 0.26 % to 1.07 % after Accelerated Aging test. The Modulus of Rupture, Modulus of Elasticity and Energy at Break increased with increase in Board Density, Mixing Ratio and Curing Reagent Concentration after Accelerated Aging test. The Modulus of Rupture ranged from 1.774 N/mm2 to 8.883 N/mm2 while the Modulus of Elasticity ranged from 720 N/mm2 to 4220 N/mm2and Energy at break ranged from 0.06 Nm to 0.16 Nm after Accelerated Aging test. The strongest, stiffest and most dimensionally stable boards were produced at the highest Board Density (1200kg/m3), Mixing Ratio (3.5:1) and Curing Reagent Concentration (3.5 %). The correlation analysis revealed a significantly high and positive relationship between Water Absorption and Thickness Swelling (0.876**), Modulus of Rupture and Modulus of Elasticity (0.988**), Modulus of Rupture and Energy at break (0.968**), and Modulus of Elasticity and Energy at Break (0.960**). While a negative relationships existed between the physical properties and mechanical properties of the Cement Bonded Composites. In addition, Cost Benefit ratio gave a value greater than unit 1, which connotes that the project is economically viable, socially acceptable and profitable. The study thus confirms that the hot water pretreated bamboo particles were suitable for the manufacturing of Cement Bonded Composites. This study should encourage research activities in the investigation of the suitability of other non-wood lignocellulosic materials in the production of composite boards.