Abstract:
The main objective is to investigate the utilization of waste polyethylene bags for the
manufacturing of non-load bearing Hollow Concrete Blocks (HCB) partially replacing
the sand volume and analyzing its effect on the compressive strength, density and water
absorption of the block. Using waste polyethylene bags as part of a construction material
can be an effective solution to the plastic pollution and also help reduce the need of
aggregate mining from the environment.
The research experiment was conducted by preparing hollow concrete block samples that
are prepared by replacing the sand volume (0%, 10%, 20%, 30% and 40 %) with
shredded waste polyethylene bags. These replacement percentages are considered to find
the possibility of attaining higher diversion of PE wastes to the HCB manufacturing.
Results showed a decrease in the compressive strength and density of the HCB with the
increase in the amount of shredded polyethylene. The decrease in the density of the
blocks is mainly due to the light weight nature of the plastic when compared to the other
aggregates. The compressive strength of the blocks up to 40% replacement of shredded
polyethylene bags was high compared to the standard compressive strength requirements
for a non-load bearing blocks, while the highest value being obtained at 10%; this is due
to the prevention and obstruction of micro fractures by the PE by obstructing its
propagations and could also be due to the increased bending strength of the plastic
converting the shear stress to tensile stress unlike the sand material.
However, the water absorption of the HCB increased with increase in the amount of PE.
Due to the coarser nature of the shredded polyethylene bags there was a reduction on the
packing efficiency of the mortar mix leading to higher pore formation and increased
water absorption. The manufacturing cost of the blocks with PE infusion also increased
as the percentage of PE replacement increased, this is due to the high cost of recycled PE
which was obtained from private recycling company. Generally, results showed that it is
viable to use shredded waste polyethylene bags as partial replacement to sand in the
manufacturing of non-load bearing HCBs.