Evaluation of Stabilized Soil Blocks with the inclusion of ‘Plastic Fibre’ as Sustainable Building Material: A Complete Review

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International Conference on Mechanical, Industrial and Materials Engineering 2013 (ICMIME2013)
1-3 November, 2013, RUET, Rajshahi, Bangladesh.
Paper ID: MS_32
Evaluation of Stabilized Soil Blocks with the inclusion of ‘Plastic Fibre’ as
Sustainable Building Material: A Complete Review
I. B. Muhit
Department of Civil Engineering, Chittagong University of Engineering & Technology,
Chittagong-4349, Bangladesh.
E-mail: imrose_cuet@live.com
Abstract
Now-a-days, huge amount of waste plastics is one of the major and important environmental hazards in Solid
Waste Management (SWM) sector. So an efficient and effluent use or management is necessary to recycle these
jungles of waste plastics. Through a fundamental research, use of these waste plastics in the specific form of
fibres in making block may prove more efficient and undoubtedly a great feedback to Solid Waste Management.
The significant effects of Plastic Fibre (which is embedded from waste plastic) on stabilized mud blocks as well
as performance effect as a sustainable building material is highlighted and reviewed in this research paper
through a systematic investigation process. By adding Portland cement, Lime and their combination was used
for preparing stabilized soil. Plastic carry bags (locally known as plastic bazar bags), plastic juice bottles and
mineral water bottles in chopped form were the major source of Plastic Fibre. These fibres were added 0.1% &
0.2% by weight of soil as reinforcement. The blocks mix compositions are different in percentage of cement and
percentage of lime with different percentage (0.1% by weight of soil & 0.2% by weight of soil) of plastic fibres.
The failure patterns of the blocks were analyzed along with tested for density as well as compressive strength in
MPa. From investigation it was found that, strength increases about 3% to 10% for different cement and lime
percentage for blocks prepared with 0.1% of plastic fibres. From failure pattern observation it was also visible
that, uses of fibres reinforcement improve ductility which was compared with raw blocks.
Keywords: Sustainable building materials, Solid waste management, Plastic fibres, Stabilized blocks, Density,
Compressive strength, Ductility.
1. Introduction
Earth in the form of mud bricks has been used as the construction material for thousands of years. To improve
physical characteristics of compressed soil masonry blocks, moist soil is mechanically compacted. But the key
problems arise from the materials, in the presence of water or moisture is low tensile strength with brittle
behavior and deterioration. Stabilization with renowned binders like cement or lime can improve the water
resisting capacity as well as strength. From H. Binici et al. (2007) and A. Mesbah et al. (2004) it is clear that, to
improve tensile strength, durability and ductility in tension and to reduce shrinkage cracking, natural fibres have
been used from long days ago. Theoretical models were also developed on composite soil blocks reinforced with
fibres subjected to shear.
The enormous amount of waste plastics is one of the major environmental concerns for recent decades as a part
of solid waste management. In mud block making uses of waste plastics in the form of fibres which may term as
‘Plastic Fibre-Mud Blocks’ is one of the interesting and efficient methods of solid waste management. The
efficiency and contribution of this type of solid waste management can be investigated through a fundamental
research. Maximum studies on natural fibres are concentrated on cellulose based or vegetable fibres, which may
obtain from renewable plant resources and it is evident from the review of the existing literature. But in case of
animal fibre, and plastic fibre as well as polystyrene fabric this resource is not valid at all. That’s why, to make
plastic fibre mud blocks appealing to all and applicable widely, some research on the physic-mechanical
properties and characteristics is indispensible. From the preliminary investigation of some systematic study, this
paper highlights and represents the key observations on the effect of embedded fibre (the source is plastic waste)
on the strength performance of stabilized mud blocks corresponding to different amount of plastic fibre.
2. Key Materials and Experimental Approach
The soil which is being collected for making blocks was carried through standard soil classification. The basic
summaries is shown in Table 1

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Table 1. Summary of Standard Soil Classification
Sand (%) Silt (%) Clay (%) Specific Gravity Optimum Moisture
Content (%)
Dry Density
(g/cc)
58.5 37.5 4.00 2.63 17.5 1.83
Soil was stabilized by combination of cement-lime. The quantity of cement and lime added was 8% & 10% and
after several trials 2% & 4% by weight of soil respectively. Similar observations regarding the quantity of
stabilizers (7.5% of cement and 2% lime) were made by Jagadeesh, 2007 at ‘Building with Stabilised Mud’.
Basically it relies on the type and nature of soil. During making of block, plastic fibre of length 20 mm were
added with mixture of 0.1% & 0.2% by weight of soil. The plastic fibre was in chopped form of carry bags
having aspect ratio 125 and mineral water bottles having aspect ratio 84. Figure 1 show some chopped plastic
fibres which wasn’t the actual picture of the experiment but supplied with this paper to identify the types and
format of the chopped plastic fibre. Seven types of sample were prepared where one is control block containing
only raw soil. The remaining six types of samples were raw soil with 8% cement, raw soil with 8% cement and
2% lime, raw soil with 8% cement and 4% lime, raw soil with 10% cement, raw soil with 10% cement and 2%
lime, raw soil with 10% cement and 4% lime respectively, having blocks size 305mm x 143mm x 100mm.
These mixture combinations are shown in tabular form in Table 2.
By pressing the prepared soil at OMC, blocks were made and straw as well as gunny bag were used to cover the
block stack during curing period. Sprinkling of water on these covers consists the curing. After 3, 7 and 28 days
the prepared blocks were tested for compressive strength by using a digital compression testing machine with
lowest count of 20 N which ranges up to 1000 kN. In the end, dry density fluctuations and effect on compressive
strength were analyzed and finally from the deep observation of failure pattern of the sample blocks the benefits
of fibre reinforcement in ductility and crack propagation properties were evaluated.
Fig. 1. Chopped Plastic Fibre
Table 2. Composition of the Blocks
Composition of the Mix Dimension (mm)
L x B x H
Sample Labeling
Raw Soil (Control Block) 305 x 143 x 100 C
Raw Soil with 8% Cement 305 x 143 x 100 C1
Raw Soil with 8% Cement and 2% Lime 305 x 143 x 100 C2
Raw Soil with 8% Cement and 4% Lime 305 x 143 x 100 C3
Raw Soil with 10% Cement 305 x 143 x 100 C4
Raw Soil with 10% Cement and 2% Lime 305 x 143 x 100 C5
Raw Soil with 10% Cement and 4% Lime 305 x 143 x 100 C6

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3. Results and Discussions
3.1 Effects on Density and Specific Gravity
There is a significant effect on density and specific gravity for different mixing proportions. From experiment it
is visible that, the density of the soil blocks with different mixing compositions varied from 1800 kg/m3 to 1898
kg/m3. Effects of different mix composition with (0.1% by weight of soil & 0.2% by weight of soil) or without
plastic fibre, on density is shown in Table 3 in the form of test result. It is also proved from experiment that
adding of plastic fibre doesn’t create a radical change in density and in almost each cases density falls slightly
after adding 0.1% fibre and density falls remarkably after adding 0.2% fibre. It is clearly shown in Figure 2.
Most important thing to mention that, the specific gravity of the fibres fluctuates within 1.07 to 1.1.
Table 3. Density (Kg/m3) for Different Composition
Sample No.
0% Fibre
0.1% Fibre
0.2% Fibre
Kg/m3 Kg/m
3
Kg/m
3
C 1889 1825 1800
C1 1892 1888 1841
C2 1883 1854 1829
C3 1855 1847 1831
C4 1898 1882 1834
C5 1885 1865 1823
C6 1866 1860 1822
1740
1760
1780
1800
1820
1840
1860
1880
1900
1920
0% Fibre 0.1% Fibre 0.2% Fibre
C
C1
C2
C3
C4
C5
C6
Fig. 2. Fluctuation of Density for Different Composition
3.2 Effects on Compressive Strength
At 28 days curing the compressive strength of the blocks fluctuated from 2.00 to 4.29 MPa depending on
different composition of mix and percentage of plastic fibre. If control blocks (C) and blocks stabilized with 8%
cement content (C1) compared, it is evident that strength increases approximately 8.5%. Moreover, 29.5%
strength increases in case of comparing between control blocks (C) and blocks consists of 10% cement (C4).
Again compared to block with 10% cement (C4) there was an increase of 5.6% and approximately 18% in
strength when this soil block was stabilized by 2% (C5) and 4% of lime (C6) respectively. The stabilized treated
mud blocks exhibits strength values ranges from 2.71 MPa to 4.14 MPa which contains 0% plastic fibre and
these may compared with the well burnt brick’s compressive strength of 3.5 MPa as per BIS 1077-1992 (Fifth
Revision). It is notable that, for all mixing compositions the blocks with 0.2% of plastic fibre the compressive
strength were reduced but it was positive for 0.1% plastic fibre. Almost in every case compressive strength was
increases significantly for the blocks with 0.1% plastic fibre. Large quantity of fibres distributed non-uniformly
in the blocks and creating weaker plane, which may leads to reduction in strength. The strength in MPa are
shown in Table 4 with sample number and Figure 3 shows the fluctuation of strength pattern with respect to
different mixing composition for with (0.1% and 0.2%) and without plastic fibre.

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Table 4. Strength (MPa) for Different Composition
Sample No.
0% Fibre
0.1% Fibre
0.2% Fibre
MPa MPa MPa
C 2.71 2.90 2.00
C1 2.94 3.36 3.00
C2 3.49 3.95 3.14
C3 2.95 3.60 3.02
C4 3.51 3.99 3.26
C5 3.71 3.97 2.85
C6 4.14 4.29 3.78
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
0% Fibre
0.1% Fibre
0.2% Fibre
C6
C5
C4
C3
C2
C1
C
Fig. 3. Fluctuation of Strength for Different Composition
From this experiment and from S.M. Marandi et al. (2008) and C. Galan-Marin et al. (2010) it can be said that
during fibre sliding, cement stabilized soil blocks provide some resistance and this leads to the increase in
compressive strength at all.
3.3 Effects on Failure Mode and Crack Propagation
The control blocks which contains only raw soil, exhibits an abrupt failure without introducing any symptoms or
warning and the mode is quick. On the contrary, the blocks with fibres were quite different in nature from
control blocks and these specimens still deformed after the ultimate load was reached and finally crack was
observed on the specimen. But these specimens showed fine irregular and distinguishable crack on its surface as
like as raw soil control blocks. S.M. Marandi et al. (2008) observed same things in a study on strength and
durability of randomly distributed palm fibres reinforced with silty-sand soils. From a complete analysis of
failure modes and crack propagation the benefits of plastic fibre was evaluated that it can improve ductility as
well as crack propagation after initial formation.
4. Conclusions
This research was conducted to evaluate the density, compressive strength and failure pattern for different
stabilized condition with 0% plastic fibre, 0.1% plastic fibre and 0.2% plastic fibre respectively. By maintaining
and following various standards this study was conveyed.
 The density of the soil blocks with different mixing compositions varied from 1800 kg/m3 to 1898
kg/m3. Adding of plastic fibre doesn’t contribute magical change in density and in almost each cases
density falls slightly after adding 0.1% fibre and density falls remarkably after adding 0.2% fibre.

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 From comparison of control blocks (C) and blocks stabilized with 8% cement content (C1), it is evident
that strength increases approximately 8.5% and 29.5% strength increases in case of comparing between
control blocks and blocks consists of 10% cement (C4).
 There was an increase of 5.6% and approximately 18% in strength when this soil block was stabilized
by 2% (C5) and 4% of lime (C6) respectively when compared to block with 10% cement (C4).
 Large quantity of fibres distributed non-uniformly in the blocks and creating weaker plane, which may
leads to reduction in strength.
 The control blocks which contains only raw soil, exhibits an abrupt failure without introducing any
symptoms or warning and the mode is quick
 The blocks with fibres deformed after the ultimate load was reached and finally crack was observed on
the specimen.
 The chopped plastic fibres from mineral water pet bottle are not consistently sound with soil in
improving the compressive strength.
5. Acknowledgement
The author wishes to thank Benny Mathews Abraham from School of Engineering, CUSAT, Kochi, India for his
intellectual contribution and help throughout the work. The inspiration of Dr. G. M. Sadiqul Islam and Dr.
Aysha Akter of Chittagong University of Engineering & Technology (CUET) are gratefully acknowledged.
6. References
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