Use of Molten Plastics in
developing alternative building
Paper presented at the 20th Institution
of Engineers of Kenya Conference held
at Tom Mboya Collage, Kisumu.
8th -10th May 2013 by
Bernadette Sabuni.
Use of Molten Plastics in developing
alternative building materials
Paper presented at the 20th Engineers’ International
Conference held at Tom Mboya Labour College Kisumu.
8th -10th May 2013
Bernadette Sabuni.
1.0 Introduction
• Plastic manufacturing is a multi-million dollar
industry. However, disposal of these plastics after
use pose environmental problems.
• Plastics in different forms are found in all
municipal solid waste.
• It is a common sight in both urban and rural areas
to find empty plastic bags and type of plastic
packing material littering the environment
• Due to its biodegradability it creates stagnation in
water and associated hygiene problems
Introduction Cont.
• It has been shown that plastics, when added
to hot aggregate will form a fine coat of plastic
over the aggregate thus improving conditions
of bonding.
• The composite material is found to have
higher strength, higher resistance to water
absorption and better performance over a
period of time.
2.0 Materials
• This research project sought to determine the
properties of samples made using molten
plastics and quarry dust.
• Waste plastics were in the class of
thermoplastics collected within the university
• Quarry dust was obtained from stock piles at
the university construction site.
2.1 Plastic Wastes
2.2 Quarry Dust
3.0 Method
• Samples were made by casting of the molten
plastic-quarry dust mix in cylindrical moulds
obtained by cutting steel tube 150mm height
and 105mm diameter.
• The were then immersed in water for 24 hours
before testing.
3.1 Melting of the Plastics
3.2 Mixing
3.4 Homogeneous Mix
3.5 Placing and Compaction of the
3.6 Curing of Samples
4.0 Results
• As percent plastic increases, the density
decreases proportionally.
• Water absorption decreases non- linearly as the
% of plastic increases. The decrease of water
absorption with increase in plastic matrix may be
attributed to the water repelling properties
associated with plastics.
• the strength increases gradually and then
exponentially from the first plot up to a value of
10.50 N/mm², then decreases with further
increase in plastic proportion
4.1 Density
4.2 Water Absorption
4.3 Compressive Strength
5.0 Conclusion
• From the study it is evident that blocks made
using waste plastic binder and quarry dust in
an optimum mix proportion can meet the
strength requirement for load bearing (>5.0
N/mm²) walls.
• The resulting composite material has water
repelling properties.
6.0 Recommendations
• There is need to test the blocks at different
temperatures to establish the behavior exhibited
• Since blocks made from this material may not be
joined using cement mortar an alternative
approach is required e.g. the mortarless
interlocking blocks
• This concept can be improved to make it feasible
in a factory setting for instance a hydram machine
can be modified to make such blocks.
7.0 Challenges
• Temperature regulation was very critical in this
exercise not only to avoid complete combustion
of plastics but also to allow mixing, placing and
compaction of the samples.
• It was noted that a temperature drop below the
melting range could caused plastic set before
• The fumes from melting plastic and the high
operating temperatures posed a risk to health.
• Also manual mixing posed difficulties in achieving
consistency of molten plastic – quarry dust mix.
Thank You for Listening
Comments, questions,

- The Institution of Engineers of Kenya