Abstract: The work presents a development of EN338 strength classes for Strombosia pustulata, Pterygotama crocarpa, Nauclea diderrichii and Entandrophragma cyclindricum Nigerian timber species. The specimens for experimental measurements were obtained from the timber-shed at the famous Panteka market in Kaduna in the northern part of Nigeria. Laboratory experiments were conducted to determine the physical and mechanical properties of the selected timber species in accordance with EN 13183-1 and ASTM D193. The mechanical properties were determined using three point bending test. The generated properties were used to obtain the characteristic values of the material properties in accordance with EN384. The selected timber species were then classified according to EN 338. Strombosia pustulata, Pterygotama crocarpa, Nauclea diderrichii and Entandrophragma cyclindricum were assigned to strength classes D40, C14, D40 and D24 respectively. Other properties such as tensile and compressive strengths parallel and perpendicular to grains, shear strength as well as shear modulus were obtained in accordance with EN 338.
Abstract: Contamination of heavy metals in tin tailings has
caused an interest in the scientific approach of their remediation. One
of the approaches is through phytoremediation, which is using tree
species to extract the heavy metals from the contaminated soils. Tin
tailings comprise of slime and sand tailings. This paper reports only
on the finding of the four timber species namely Acacia mangium,
Hopea odorata, Intsia palembanica and Swietenia macrophylla on
the removal of cadmium (Cd) and lead (Pb) from the slime tailings.
The methods employed for sampling and soil analysis are established
methods. Six trees of each species were randomly selected from a
0.25 ha plot for extraction and determination of their heavy metals.
The soil samples were systematically collected according to 5 x 5 m
grid from each plot. Results showed that the concentration of heavy
metals in soils and trees varied according to species. Higher
concentration of heavy metals was found in the stem than the
primary roots of all the species. A. Mangium accumulated the highest
total amount of Pb per hectare basis.