Journal of Minerals & Materials Characterization & Engineering, Vol. 11, No.4, pp.437-443, 2012 Printed in the USA. All rights reserved
Mechanical Propertie s of H ybrid Cement itous Composites
I.O. Oladele*, A.D. Akinwekomi and U. Donatus
Department of Metallurgical and Materials Engineering, Federal University of Technology,
Akure, Ondo State, Nigeria.
*Corresponding author:
Pulverised stem fibres of the natural sponge plant, SP, (Acanthus montanus) and stranded
coconut fibre, CF, (Cocos nucifera) from the coir tree were used as reinforcements for thin
cement sheets in this research work. The mixture of cement and pulverised waste paper,
which formed the matrix, was maintained constant while the fibre mass concentration of both
fibres were varied. The slurry formed b y adding water to the mi xture of the matrix materials
and the reinforcement fibres, was poured into rectangular mould and consequently pressed to
eject excess water. De-moulded samples were allowed to cure in the laboratory for twenty-
eight days before flexural and compressive tests were carried out. The analysis of the
experimental results established that sample coded as S4, with 30% CF and 70% SP, showed
the most promising result. This implied that particulate reinforcement in cement matrix
composite contributed to higher and improved flexural load bearing capacity and ductility
when utilised in a higher proportion than long fibres.
Keywords: Mechanical properties, hybrid, natural sponge, coconut fibre, cement matrix.
438 I.O. Oladele, A.D. Akinweko mi and U. Donatus Vol.11, No.4
The use of fibres as reinforcement is as old as human civilization. Traces of natural fibres
such as flax, cotton, silk, wool and plant fibres have been located in ancient civilizations all
over the globe. For example, the recorded usage of flax can be dated back to 5000 BC; it is
considered the oldest natural textile fibre [1, 2]. More recently, the use of natural fibres in
construction has been limited to thin elements for roofing, cladding, and internal and external
partitioning walls; these have been produced in an effort to develop low cost materials and as
a substitute for asbestos, especially in the developing economies.
Today, a deficit of habitations is a major problem in bot h developed societies and developing
countries. Little attention is given to the problem; while millions of people live in sub-human
conditions, the majority of researchers direct their projects towards the development of
advanced materials and sophisticated analysis of structural systems [3].
The development of low cost materials with high durability and enhanced mechanical
properties becomes a real challenge to the engineers of the 21st century. Environmental
issues such as the greenhouse effect have also become major concerns. The lee way may,
perhaps, be viewed in bio-degradable composite systems with low cement content. These
composites can find applications in various fields such as permanent formworks, rowing-
boats, facades, tanks, domestic pipes, corrugated and flat roofing elements, insulating panels,
strengthening of existing structures and structural building members.
The geometrical increase in the world population signifies that more reinforced concrete
structures will be built with an accompanying deterioration problems coupled with increase in
the demand for non-renewable resources [4].
Natural fibres are a renewable resource and are available almost all over the world [5].
Therefore to promote the use o f concrete reinforced with n atural fibres could be a viable wa y
to improve concrete durability and sustainable construction which will alleviate the problems
of housing and environmental degradation resulting from the use of non-renewable resources.
Therefore, the aim of this paper is to make use of the combination of coconut fibre of a
specified length and particulate natural sponge fibre for the production of ceiling board for
the building industry.
The materials used for this research work were all sourced and obtained locally. These
included fibres from the stem of the natural sponge plant, SP, (Acanthus montanus), coconut
fibre, CF, (Cocos nucifera) from the coir tree, pulverised waste paper from old newspaper
pages, wooden moulds, polythene sheets and Portland cement. The CF were cut down to
40mm length to avoid balling problem during mixing and to facilitate homogeneous mixing
of the composite [6] while the SP fibres were pulverised.
The variable in this research work was fibre mass concentration. The mixture of cement and
waste paper in the ratio 70:30 by weight was maintained constant. The fibre mass fractions,
Mf aimed at were Mf = 0, 2,4,6,8 and 10%. This fibre mass fraction was defined as the ratio
of fibres to the dry constituents of the matrix (cement and waste paper) by weight [7]. Table 1
below gives the matrix and fibre mass compositions utilized for this research work.
Table 1. Matrix and Fibre Mass Compositions
Fib r e
Weighed masses of pulverised paper, cement and fibres were homogeneously mixed together.
Water was then added until suitable slurry was formed. The slurry was poured into the
rectangular moulds measuring 150mm X 50mm X 30mm and labelled with the corresponding
mass fraction. A-5 ton hydraulic jack was used in compressing the composites for
approximately one hour until excess water was dispelled before they were de-moulded. The
composites produced were allowed to cure in the laboratory air for twenty-eight days before
mechanic al test s were carried out. Three s amples were tested fo r each fo rmul a and a mean of
the results was recorded.
440 I.O. Oladele, A.D. Akinweko mi and U. Donatus Vol.11, No.4
2.1. Flexural and Compressive Tests
Flexural test based on the three-point loading principle was carried out on the Tensometric
Testin g Machine. The flex ural load (force at peak) and deflect ion at yield were automatically
generated by the machine. The compressive test was also done on the same machine.
3.1. Flexural Load
The flex ural load (force) is the max imum load t he compos ite can b ear befo re fracture du ring
flexure/ bend test [6]. Figure 1 depicts the results graphically.
Samples S3 and S4 exhibited the higher and highest resistances to applied load respectively,
with S3 having 143.75 N while S4 had 156.10 N. S 1 closely followed with a v alue of 130.95
N. However, S9 had the lowest value of 115.35 N. The trend observed was that as the CF
fraction increased in the matrix, the flexural strength also increased from S2-3, reaching a
peak for S4, before decli ning for S9. The implicat ion of this is that the fibres included in the
matrix actually contributed to strengthening and delayed matrix cracking according to Brandt,
2008. SP, in the particulate form seemed to show better strengthening when it has a higher
volume fraction in the matrix than CF. S10, however, did not follow the observed trend. It
showed quite a high resistance to fracture with a value of 99.70 N. The relatively high
flexural load could have been due to CF, being present in a larger fraction than SP.
3.2. Flexural Deflection (Mid-span deflection)
The flexural (mid-span) deflection is a measure of both the ductility and toughness of each of
the samples [6]. The results of this test are presented in Figure 2 below:
S4 had the highest ductility value of 1.2 mm while S3 had the poorest ductility with a value
of 0.0870 mm. This was followed closely by the control sample, S1, with a recorded value of
0.1070 mm. Excepting the S3 sample, the fibre reinforcement generally improved ductility
when compared with S1, the unreinforced sample. Improvement in ductility was, however,
not prominent for S3 and S8 (values of 0.0870 mm and 0.1300 mm respectively). S9 also
exhibited the next higher value of ductility of 0.7155 mm. It contained a higher fibre fraction
of CF than SP. Though no general trend could be established for this property, some extreme
peaks could be established, especially for S4 (higher fibre fraction of SP) and S9 (with a
higher proportion of CF).
3.3. Compressive Load
The compressive strength reported is compressive force at peak. The results are shown in
Figure 3 below:
S1 exhibited the highest resistance to compressive load, with a value of 5737.0 N. This was
followed closely by S4 and S3, with values of 5193 N and 4476.0 N respectively. The high
resistance to compression depicted by S1 could be at tributed t o the presen ce of few o r no air
442 I.O. Oladele, A.D. Akinweko mi and U. Donatus Vol.11, No.4
pores in its matrix. The incorporation of fibres into the matrix introduced some air pores. This
accounted for the reduction in the compressive loads that could be sustained by the test
samples. This is also true for the other reinforced samples (i.e.S2 to S10).
The results and analyses of the data obtained from this research work showed that randomly
distributed natural vegetable fibres could be used to improve the flexural strength of flat
cement composite sheets. S4, with 30% CF and 70% SP, showed the most promising result.
This implied that particulate reinforcement in cement matrix composite contributed to higher
and improved flexural load bearing capacity and ductility as measured by the mid-span
deflection. Compressive load was not adversely affected by the inclusion of fibres in the S4
sample. Strength and ductilit y showed better improvement at the optimum fibre mass fraction
of 70% SP and 30% CF.
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Structures- A New Perspective”, CBM-CI International Workshop, Karachi, Pakistan.
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Vegetable Fibre-Mortar Composites of Improved Durability”, Cement & Concrete
Composites, Vol. 25, pp. 185-196.
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“Potential of Crushed Waste Calcined-Clay Brick as a Partial Replacement for Portland
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6. Oladele, I.O., Akinwekomi, A.D., Aribo, S., and Aladenika, A.K., 2009, “Development of
Fibre Reinforced Cementitious Composite for Ceiling Application”, Journal of Minerals
& Materials Characterization & Engineering, Vol. 8, No.8, pp 591-598.
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Composites, (eds. H.W. Reinhardt and A.E. Naaman), E and FN Son, London, pp. 84-99.