EVALUATION OF THE MECHANICAL PERFORMANCE AND
COMMERCIAL OPPORTUNITIES OF THICK BASALT COMPOSITE
STRUCTURES
E. Archer¹, S. Buchanan², S. Kirby², A.T. McIlhagger¹
1. Engineering Composites Research Centre, University of Ulster,
Jordanstown, Northern Ireland, BT37 0QB.
2. Axis Composites Limited, The Innovation Centre, NISP, Queens
Road, Belfast BT3 9DT.
ABSTRACT
New basalt fibre composite applications could be commercialised due to
the potential low cost of this material together with its good mechanical
performance, in particular at high temperature. In this work the possibility to
replace glass fibre was investigated where mechanical tests were carried out on Eglass and basalt fibre reinforced plastic laminates. The basalt laminates tested
were manufactured using press forming and the E-glass laminates were
manufactured using a VaRTM method. The results obtained on the two fibre
laminates were compared showing improved performance of the basalt material
in terms of tensile modulus. Furthermore, compression after impact strength
(CAI) was obtained for the 15mm thick basalt laminates. These properties suggest
possible applications of basalt fibres in fields where glass composites are
nowadays largely dominant.
KEYWORDS: Basalt fibres, Basalt Composite
1.
INTRODUCTION
Basalt is a natural material that originates from volcanic rocks and has
traditionally been used (as crushed rock) in construction, industrial and highway
engineering. However, additional applications are being found for this versatile
and environmentally friendly material for instance the melting of basalt (13001700°C) and spinning it into continuous reinforcing fibres where these can be
used in downstream processes to manufacture a composite material/product for a
diverse range of applications [1].
When used as fibres, basalt can reinforce a new range of composites
consisting of polymer matrices or aggregates, which are tailored towards the
specific performance requirements of the end application. It can also be used in
combination with other reinforcements (e.g. basalt/carbon fibres) to produce
hybrid composites with multifunctional application such as high strength,
temperature, fire resistant and light weight performance.
The development and implementation of basalt fibre reinforced composites
into industrial applications is in its infancy when compared with other industrial
fibre reinforced composite types such as glass where the annual world production
of glass fibres is in the region of 3.5-4 million tonnes in contrast to basalt fibre
production of 3000-5000 tonnes.
Basalt fibre composites offer new possibilities to achieve performance that
is superior to E-glass and comparable to S-2 glass at a competitive price (e.g. 1620 £/kg for S2 glass fibre versus 2-3 £/kg basalt fibre). The potential applications
and opportunities are numerous for instance, high temperature resistance
materials (e.g. brake system components), structural damping materials (e.g.
tripods, generator panels etc), wind turbine blades (e.g. spar caps), automotive
parts (e.g. high temperature shielded panels) and personnel and vehicular
protection modules (e.g. ballistic protection, fire protection etc.) [2]. This
opportunity could be of particular importance to the Northern Ireland economy
and Basalt rock deposits are in abundance in the region.
2.
MATERIALS AND METHODS
For this study Basalt composite plaques were manufactured using Cray
Valley Encore 30 unsaturated polyester resin with 13 layers of 2 and 2 twill
1500gsm Basalt fibre with a saline size. The fibre and resin was deposited onto
the platens of a single daylight heated press at 140 oC plate temperate. The fibre
and resin was allowed to reach equilibrium temperature and a dwell time of 10
minutes was applied. The platen spacing used was 15mm.
E-glass fibre composite plaques were manufactured for comparison using
the VaRTM method with 8 layers of plain weave (200gsm) cut to 350mm x
350mm using a scalpel blade on a glass cutting table. A caul plate was used in
conjunction with a flexible membrane to consolidate the fabric reinforcements
under full vacuum, prior to the injection of resin by peripheral gating at a tool
temperature of 75oC. Araldite LY564 and Hardener HY2954 (based on bisphenol
A epoxy and a cycloaliphatic amine hardener) was mixed and degassed at 2.86:1
by weight before transfer of the resin. After injection, a ramp was applied to
100oC. The temperature was held isothermal for 60 minutes; the composite
plaque was then de-moulded and post cured for a further 180 minutes at 140oC.
Figure 1. VaRTM apparatus.
After cure test coupons were extracted using an OMAX 2626 WaterJet
Machining Centre. Fibre volume fraction was measured using the density
buoyancy method in which the sample’s mass in air is recorded before weighing
the sample again in distilled water according to ASTM D792-91 [2]. Therefore,
having obtained the specific gravity and knowing the densities of the constituent
parts i.e. the fibre and resin, the percentage content of the fibres was calculated.
Tensile specimens were tested in the warp direction on a Zwick Z100
universal tester. The testing was performed to CRAG standard 300 [3]. An MTS
632.85F biaxial extensometer was used to determine tensile modulus and
Poisson’s ratio.
Further Basalt specimens were impacted according to ASTM
D7136/D163M -05 using an Instron 9200 Series drop weight impact tester at 6.7
J/mm thickness. After impact, samples were secured within the Compression after
impact testing rig. The CAI rig is described within the SACMA SRM 2R-94 test
standard and is based on the Boeing Model No. CU-CI CAI testing rig. The rig
has anti buckling rails on either side of the vertical supports.
2. RESULTS AND DISCUSSION
Table 1 shows the results for tensile modulus and Poisson’s ratio for the
two composites tested.
Table 1. Elastic tensile properties for Basalt and E-Glass composite.
Poisson's ratio
Basalt Composite
Tensile Modulus
GPa
26.4
E-Glass Composite
21.8
0.16
0.15
The results show that the elastic modulus of both composites is similar but
the basalt composite appears to have an advantage. This agrees well with the
findings of Lopresto [5] who found glass fibre samples to have a modulus of
16GPa and the basalt samples 25GPa. However, it should be noted that modulus
of the composite will change with the fibre volume fraction (Vf) so density
buoyance was conducted to determine composite Vf for both test materials. Also
it was noted that the stiffness of the composite could be affected by both the
weave style and the fabric areal weight, both of which will impact on the level
crimp exhibited by the reinforcing fibres. The E-glass used in this study was a
plain weave whereas the basalt composite was a twill weave (Figure 2). The Plain
weave style has a greater propensity for fibre crimp than a more open weave like
a harness satin on a twill weave. Conversely a lower areal weight which results
from finer fibre bundles tends to produce a fabric with less crimp than a more
coarse fibre bundle.
Figure 2. Plain weave and Twill weave.
Also the composite modulus is determined by the fibre modulus, and to a
lesser extent the modulus of the resin will also have an effect on the composite
resin according to the rule of mixtures:
EL  E1f V f  Em (1  V f )
(1)
Where:
EL= Longitudinal modulus of the composite
E1f= Longitudinal modulus of the fibre
Vf= Fibre volume fraction
Em= Modulus of the resin
The density buoyancy tests showed a density of 1890 kg/m3 for the basalt
composite and a density for the E-glass composite of 1830 kg/m3. Both plaques
had a fibre volume of approximately 50%.
-From the experimentally measured density buoyancy readings the following
can be calculated:
A
(0   L )   L
Relative density = A  B
(2)
Where:
A = apparent mass of specimen in air
B = apparent mass of specimen completely immersed in water
 0 = density of the liquid (appendix B)
 L = air density (0.0012g/cm3)
Fibre volume fraction is then calculated as follows:
Vf =
c  m
 f  m
(3)
Where
 c = density of composite
 m = density of matrix
f
= density of fibre
The Compression after impact strength of the thick Basalt fibre composite
was found to be 57MPa. This is much lower than the values recorded by Aktas
[6] who examined glass fibre epoxy composites which gave a CAI strength of
over 100MPa. It is believed that this could be due to the low performance of the
polyester resin that allowed a large amount of delamination in the composite
during impact testing.
4.
CONCLUSIONS
Basalt fibre composites appear to show improved tensile modulus
compared to E-glass composite for a similar density and fibre volume fraction.
However, the Compression after impact value was lower than expected. It is
thought that this might be improved by using a tougher resin system and ensuring
the resin is cured correctly. Further work is required to determine the optimum
parameters for maximum CAI properties.
4.
REFERENCES
[1] J. Sim , C. Park, DY. Moon, Characteristic of basalt fibre as a strengthening
material for concrete structures. Compos: Part B 2005;36:504–12.
[2] T. Czigan, Special manufacturing and characteristics of basalt fibre
reinforced hybrid polypropylene composites: mechanical properties and
acoustic emission study. Compos Sci Technol, 2006;66:3210.
[3] ASTM D792-91, Standard Test Methods for Density and Specific Gravity
(Relative Density) of Plastics by Displacement.
[4] CRAG Standard Method 302 "Method of test for the Tensile Strength and
modulus of multidirectional Fibre Reinforced Plastics”.
[5] V. Lopresto, C. Leone , I. De Iorio, Mechanical characterisation of basalt
fibre reinforced plastic. Composites: Part B, 42 (2011) 717–723.
[6] M. Aktas, C. Atas, BM. Içten, R. Karakuzu, An experimental investigation
of the impact response of composite laminates. Compos Struct,
2009;87(4):307–13.