Assessment of the performance of unplastered pet bottle masonry walls in noise reduction.
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Date
2021-02-15Author
Rwothungeo, Rodgers
Tumwebaze, Arnold
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Environmental noise has long been recognized as a nuisance affecting the quality of life and wellbeing
with certain levels of it known to cause severe health problems to those who are exposed to
it. Several noise mitigation strategies exist: a barrier may be constructed between the noise source
and the receiving end. This barrier may be classified according to the acoustic comfort it avails.
From the inception of the ecofriendly PET bottle masonry in the construction of walls for
dwellings, little is known about the acoustic performance of this material. This research focused
on assessment of the performance of unplastered PET bottle masonry walls in noise reduction and
it zeroed in on the effect of composite wall density, effective wall thickness and the sound
frequency of sound on the performance.
Five unplastered PET bottle masonry wall models were erected using ‘bottle’ bricks bonded in
cement and sand mortar with the designations; BSW (for 2l sand-filled bottle wall), MSW (for
500ml sand-filled bottle wall), SSW (for 330ml sand-filled bottle wall), SPW (for 330ml
polyethene-filled bottle wall) and SAW (for 330ml air-filled bottle wall). The walls were tested
for composite wall density using the displacement method for volume and their effective wall
thicknesses determined in accordance to BS EN 1996-1-1:2005 Part 5.5.1.3. Their respective
airborne sound insulation performance was tested in accordance to BS EN ISO 16283-1:2014 and
finally, they were acoustically classified in based on ISO/DIS 19488.
From the study, it was found out that increasing the composite density of the wall by using denser
material as infill in the bottles of the wall brought about an increase in the sound reduction
properties of the wall. This however is not true for other infill materials like air that have different
sound attenuation mechanisms yet they are less dense. In effect, SAW performed better than the
SPW yet it is less dense. Increasing the wall thickness also brought about better performance in
the walls however, this result was compounded by an increase in the wall density with increase in
thickness. Also, the more massive walls (BSW and MSW) performed best in the high sound
frequency range compares to the less massive ones, yet the converse was true in the low sound
frequency range where the less massive walls like SSW performed best in sound insulation. In
accordance to ISO/DIS 19488, BSW, MSW and SSW was of acoustic class E while SAW was of
class F and SPW was of no performance defined (npd) in space type 2. All walls were npd in space
types 1 and 3.