Properties Of 10 Ghanaian High Density Lesser-Used-Species Of Importance To Bridge Construction – Part 2: Mechanical Strength Properties

Abstract

Logs from sixty trees of ten high density Lesser Used Species (LUS) of potential importance to bridge construction were extracted from four forest reserves -Bobiri, Pra-Anum, Nueng, and Subri River in four different ecological zones. The logs from the trees were converted on a horizontal bandmill to 27 and 53 mm thick boards. One-half of the boards were used in the green state and the other half air dried. Mechanical strength test specimens were prepared and tested in accordance with the British Standard BS 373:1957. The range of mean strength values in N/mm 2 in the 'green' [and dry] conditions for the ten wood species were as follows: -Modulus Hardness in kN: 3.5-11.3 [5.1-17.0]. The 10 species in decreasing order of strength was as follows: Lophira alata (Kaku) > Cynometra ananta (Ananta) > Strombosia glaucescens (Afina) > Celtis mildbraedii > Nauclea diderrichii (Kusia) ≥ Celtis zenkeri ≈ Piptadeniastrum africanum (Dahoma) > Nesogordonia papaverifera (Danta) > Combretodendron africanum (Essia) > Sterculia rhinopetala (Wawabima). Mean ratios of dry to 'green' MOR and MOE were 1.44 and 1.28. There was a good correlation (84.4~98.2%) between the Density (X) and the various mechanical strength values (Y). Regression equations in the form: Y = aX b were derived with R 2 values of 0.72-0.93.

Assessment of physical and mechanical properties of juvenile and matured Bambusa vulgaris glue-laminated bamboo for structural applications in Ghana

“…This could further suggest that higher MOE is an assurance in terms of material utilization potential, especially for structural and non-structural applications in both the furniture and building construction industries. In addition, matured glue-laminated bamboo compares favourably with some of the tropical hardwood species like Khaya ivorensis with an MOE of 9113 MPa [42][43], Sterculia rhinopetala with an MOE of 13382 MPa [44], Combretodendron africanum with an MOE of 9739 MPa [45]. The matured glue-laminated bamboo with MOE of 13379 MPa could be used for similar construction works in Ghana since the MOE compares favourably with the above wood species.…”

“…Additionally, matured glue-laminated bamboo could also compare favourably with some of the tropical hardwood species like Khaya ivorensis with an MOR of 73.9 MPa [43], Sterculia rhinopetala with an MOR of 81.7 MPa [44], Combretodendron africanum with an MOR of 103.7 MPa [45]. Comparatively, the matured glue-laminated bamboo with an MOR of 82.48 MPa could be used for similar construction works in Ghana since the MOR compares favourably with the above wood species.…”

Properties Of 10 Ghanaian High Density Lesser-Used-Species Of Importance To Bridge Construction – Part 1: Green Moisture Content, Basic Density And Shrinkage Characteristics

“…Specimens were prepared from the green boards for the determination of the green moisture content, basic density, and dimensional shrinkage (from green to 12% moisture content and from green to oven-dry state) for all ten species. Some boards were cut and stored for subsequent mechanical strength (Ofori et al, 2009b) and woodworking studies.…”

Study Effect of Carbon: Nitrogen Ratio on the Minerals Weathering by Using Scanning Electron Microscope

“…Although conventional wood preservatives are very effective against wood destroying organisms, they are also hazardous to the environment, animals and human beings [5][6][7][8][9][10][11][12][13][14][15] because they have very long bio-degrading lives. Even CCA which was previously thought to be stable in wood has now been found not to be.…”

“…One readily accessible less hazardous option is the treatment of low durability timbers with extractives from highly durable ones, most of which are quickly biodegradable. Extractives from the heartwood of highly durable timbers are mostly used [7][8][9][10][11][12][13][14] while those from other parts of trees like leaves, bark, root, needles and seeds are seldomly used. However,the fraction of extractive compounds in stem bark is four to five times that of bark free wood, and needles have seven to eight times that of bark free wood 13 .…”