Abstract:
Plastic production has overtaken most man-made materials including metals and has long been under environmental scrutiny.
Most plastic wastes are accumulated in landfills, natural environment and oceans. It is estimated that with the current trend of
global production and waste management, approximately 12000 million metric tons of plastic waste will accumulate in landfills
and in the natural environment by the year 2050. Plastics have very poor recycling rates, and their inherent menace is most
pervasive in low-income, developing countries. This paper presents results of study on plastic waste as binder in mixtures of sand
(fine aggregates) to produce building blocks for construction. Melted polyethylene plastic was mixed with sand (sandplast) in
different proportions of 1:1, 1:1.5, 1:2, 1: 2.5 and 1:3 (plastic: sand). Test results include compressive, tensile and impact
strengths, stress-strain response, fire resistance, water absorption and permeability of sandplast. The optimum mix ratio for the
compressive, tensile and impact strength was 1:2. The compressive and tensile strength of sandplast blocks ranged from 4.8 to
7.4 N/mm2 and 3.3 to 7.2 N/mm2
respectively. These are greater than the respective values for sandcrete blocks produced in
Ghana that generally vary from 1.4 to 3.5 N/mm2
and 0.1 to 0.3 N/mm2
. The static modulus of elasticity of sandplast averaged
approximately 89.0, 311.5 and 197.7 N/mm2
for mix proportions of 1:1, 1:2 and 1:3. At temperatures below 80oC the strength
properties and stability of sandplast blocks remained unchanged. When immersed in water, sandplast blocks were found to be
insoluble in water. The coefficient of permeability of sandplast averaged 4.6 x 10-4
, 8.2 x 10-4 and 21.8 x 10-4
cm/sec for mix
proportions 1:1, 1:2 and 1:3 respectively.
