Properties Of Cement Syntactic Foam Composite For Sound Insulation Application
Loading...
Date
2018-08-01
Authors
Hasan, Norwanis
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
An innovative technique, in producing Cement Syntactic Foam (CSF)
composite, is proposed in this research project. This cellular composite material
consists of a cement matrix embedded with in-house developed Cement Hollow
macrosphere (CHS). Simple and innovative approach was implemented in the
preparation of CHS where expanded polystyrene (EPS) beads were used as initiation
material to generate the hollow sphere. The EPS beads were coated with the epoxy
resin and cement powder, were later cured and post-cured at high temperature. This
process shrinks the EPS beads thus producing a hollow sphere structure. The CHSs
were coated for second and triple coating as to vary the wall thicknesses. The CSF
composites produced by CHS with single, double and triple coatings are referred as
CSF-1x, CSF-2x and CSF-3x, respectively. The process of pre-determined amount of
CHS before fabricating the CSF composite, gave an optimal packing of sphere as to
achieve well distributed void. This step successfully reduced the density of CSF-1x,
CSF-2x and CSF-3x, almost 51%, 47% and 41% respectively in comparison to the
control plain cement (PC). The compressive strengths of CSF-1x, CSF-2x and CSF-3x were 8.9, 11.7 and 13.3 MPa, respectively. From the comparative compressive properties of CSFs it were found that the CSF incorporated with thicker-coatings of
CHS showed a higher compressive strength than that incorporated with thinner-coatings of CHS. The failure patterns within the test samples are examined to determine the failure mechanism. These observations show that both CSFs exhibited
shearing type failures, but with different types of crack fractures caused by
differences in CHS wall thicknesses. Acoustic tests (sound absorption and sound
transmission loss) were conducted to examine the acoustic behaviour of CSF in
comparison to PC. The sound absorption coefficient in CSF at frequencies of 400 Hz
to 1600 Hz was in the range of 0.15 to 0.25, whereas the PC was below 0.15. The
significant improvement of sound absorption in CSF over PC can be attributed to the
presence of open porosity combined with rough internal pores on its surface. This
rough and porous structure allows considerable sound wave dissipation via friction
when in contact with the CSF surface sample; thus raising the sound absorption
coefficient. The sound transmission loss in CSF at frequencies of 400 Hz to 1600 Hz
was in the range 20 to 60 dB; whereas the PC was in the range 60 to 80 dB. The
closed-cell structure of the CSF prevented the passage of air, thus giving high
resistance to the sound wave’s travel as similarly experience by PC. The simulation
study was successfully performed using ANSYS-FLUENT 14 software. From the
simulation, it was found that the interaction between the properties of the material
and sound pressure can be visualized; which usually is difficult to achieve in a
laboratory setting.