Cape Town – New research has found that a new composite material made from invasive Port Jackson trees and recycled low-grade plastic waste could help to eradicate South Africa’s social housing crisis.
It was developed by Dr Abubakar Sadiq Mohammed, whose recent doctoral studies showed that a combination of these two types of waste may be used to build better low-cost houses.
In December last year, Dr Mohammed, received his PhD in wood product science from Stellenbosch University’s (SU’s) Faculty of AgriSciences.
Dr Mohammed’s dissertation is titled “Properties of wood-plastic composites made from alien invasive tree waste and recycled low-density polyethylene for interior use in social housing”.
It underlines the urgent need to find sustainable solutions for South Africa’s social housing challenges.
Through his research, he developed a wood-plastic composite using a mix of biomass from all parts of a Port Jackson tree (Acacia saligna) and recycled, low-density polyethylene.
This light polymer is primarily used in packaging such as plastic bags.
“Plastic waste is a known global menace, so the idea was to transform this waste material into something useful,” he said.
“I was also interested in developing affordable, eco-friendly alternatives to existing low-cost building materials.”
Wood-plastic composites are generally made from recycled plastic and small wood particles or fibres.
Typically, manufacturers separate the woody parts of the chosen plants used from the non-woody parts (such as bark, leaves and seeds). Until now, the non-woody parts of alien invasive trees were considered contaminants rather than suitable components from which to produce composite materials.
Dr Mohammed analysed the physical and mechanical properties of the new composite boards and determined how well the material performed in terms of certain processing requirements.
Specifically, Dr Mohammed tested the boards’ resistance to mould infestation and analysed their fire-resistant properties.
He also considered the impact of the thermal degradation of the individual biomass constituents (such as bark, twigs, leaves and wood) on the physical, mechanical, acoustic and thermal insulation properties of these boards.
His results show that wood-plastic composites made with Port Jackson trees have better mechanical properties, regardless of their exact composition, compared to two other invasive species, black wattle (Acasia mearnsii) and red river gum (Eucalyptus camaldulensis).
Cape Times