Vol. 9 | No. 4 |706 - 715 | October - December | 2016
ISSN: 0974-1496 | e-ISSN: 0976-0083 | CODEN: RJCABP
http://www.rasayanjournal.com
http://www.rasayanjournal.co.in
STUDY ON THE STRENGTH PROPERTIES OF MARINE
ALGAE CONCRETE
R. Ramasubramani*, R. Praveen and K. S. Sathyanarayanan
Department of Civil Engineering, Faculty of Engineering and Technology,
SRM University, Kattankulathur-603 203, Tamil Nadu, India.
*E-mail: [email protected]
ABSTRACT
Study on marine algae was performed which concluded that the chemical reaction with the cement makes the
environment free from pollution. Since algae are environmental friendly, this makes the concrete more economic
and, at the same time, there is a reduction of the problem on waste. In this study, marine brown algae were used as
additive material to concrete. With a fixed water to cement ratio (W/C = 0.5), marine brown algae is added at 2%,
5%, 8% and 10% from the cement content in producing M25 grade concrete. Harden tests were performed at 3, 7
and 14 days. The results showed that the various strength properties of concrete increased or decreased with addition
of marine algae. The compressive strength tends to decrease for more addition of marine algae. Deflection
characteristics test showed that the ultimate load carrying capacity of optimum mix concrete beam was higher than
conventional concrete beam. This study shows that 8% addition of marine algae to concrete showed an increase in
strength properties and when the addition increased to 10% the properties started to decrease.
Keywords: Marine brown algae, compression test, spilt tensile, Flexure, E-value.
© RASĀYAN. All rights reserved
INTRODUCTION
Algae are photosynthetic aquatic plants that utilize inorganic nutrients such as nitrogen and phosphorus.
The Phaeophyceae or brown algae, is a large group of mostly marine multicellular algae, including many
seaweeds. Worldwide there are about 1500–2000 species of brown algae. Some species are of sufficient
commercial importance, such as Ascophyllumnudism, that they have become subjects of extensive
research. Most brown algae contain the pigment fucoxanthin, and hence they are in greenish brown
colour.
Genetic studies show their closest relatives to be the yellow green algae. Brown algae exist in a wide
range of sizes and forms. The smallest members of the group grow as tiny, feathery tufts of threadlike
cells no more than a few centimeters long. Some species have a stage in their life cycle that consists of
only a few cells, making the entire alga microscopic.
Other groups of brown algae grow too much larger sizes. These are used as fertilizer, energy source, and
food source, for pigments, pollution control, and medicinal purposes. Concrete based on Portland cement
is the most widely used construction material in the world, and its production follows a trend of growth.
In 2011, the world production of Portland cement reached 2.8x109 tonnes and is expected to increase
around 4x109 tonnes for the 2050. About 15% of the total concrete production contains chemical
admixtures, which are chemicals added to concrete, mortar or grout at the time of mixing to modify their
properties, either in fresh or hardened state
Need for this study
Research is always more interested in the use of such products in the concrete mix. This makes the
concrete more economic and, at the same time, there is a reduction of the problem in waste. By studying
the properties of algae concrete the work is necessary in pollution less environment and to avoid the voids
in concrete.
STRENGTH PROPERTIES OF MARINE ALGAE CONCRETE
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Vol. 9 | No. 4 |706 - 715 | October - December | 2016
Marine algae
About 71% of the world is surrounded by ocean. The most important herbivores in ocean are
phytoplankton and benthic algae. The marine algae familiarly known as seaweeds are a diverse group of
photoautotrophic organisms of various shapes (filamentous, ribbon like, or plate like) that contain
pigments such as chlorophyll, carotenoids, and xanthophylls’. The growth of marine algae is abundant in
coastal area since sandy beaches provide excellent attachment points in a constantly moving and dynamic
environment of the sandy shore. The first type of plant life to attach itself to the coastal concrete structure
is a filamentous macro algae. The colonization is likely to be, due to the constant abrasion of the lower
regions by the action of the tide lifting the sand and small stones from around the base of the structure. A
number of seaweeds can be found in this type of environment although there are usually a few dominant
species like Chaetomorpha antennae. These green algae are classified in the Phylum Chlorophyta. Many
species of green algae grow attached to rocky and concrete substrates on or near the ocean's surface. In
general, because they are attached to a substrate, they are not tossed up on the beach by the waves.
Marine brown algae concrete
Marine Algae are the one of the nature friendly substance. It controls the chemical reaction of Cement. It
avoids voids and decrease permeability of the concrete. Marine algae are the self-consolidating concrete
(SCC). Marine algae, which are, can reduce the metal equilibrium concentration to very low levels in
metals. In this Fig.-1 shows the marine brown algae. Then Fig.-2 shows the collecting to the brown algae.
It will help to avoid the voids of concrete. So the various percentages of wet and dry marine brown algae
concrete 2%, 5%, 8% and 10% is used on concrete.
Fig.-1: Marine Brown Algae
Fig.-2: Collecting Marine brown algae
EXPERIMENTAL
The project deals with the study of concrete when marine algae are added to concrete at different
percentages. The primary concern of this study is to determine the strength characteristics of marine algae
concrete.
1. Cube Specimens
A mould of internal dimensions of 150 × 150 × 150 mm was used for casting of cubes for compression
strength for both conventional concrete and maine algae concrete Specimens.
2. Cylinder Specimens
A mould of internal dimensions of 100 mm diameter and 200 mm height was used for casting of cylinder
for split tensile strength for both conventional concrete and steel fiber reinforced concrete Specimens. The
Fig.-3 shows the Casting of Cubes and cylinders.
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Fig.-3: Casting of Cubes and cylinders
3. Beam Specimens
A mould of internal dimensions of 100 × 100 × 500 mm was used for casting beams for flexural strength
for both conventional concrete and marine algae concrete specimens. Fig.-4 shows the casting of flexure
beams.
Fig.-4: Casting of flexure beams
Long Beams
A mould of internal dimensions of 150 × 200 × 1200 mm are used for casting of long beams tested under
two point loading for deflection and crack formation, for both conventional concrete and optimum
mix proportions. The Fig.-5 shows the wooden moulds used for casting of long beams.
Casting and curing of specimens
The ingredients of the concrete i.e., cement, fine aggregate, coarse aggregates, etc., were collected
according to the specified specifications and mixed in concrete mixer according to the mix proportions.
The concrete was placed in moulds as specified pervious sections. The concrete was laid in three layers
and each layer was tamped with the tamping rod, after filling the mould completely, the moulds should
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vibrate by keeping on a vibrating machine.After casting the specimens were kept undisturbed for 24
hours. The specimens would de-mould and kept it in a curing tank in which the water should be at least
50 mm above the specimen surface. Fig.-6 shows the curing of specimens in curing tank. The curing of is
done for 28 days to attain the target mean strength the design concrete grade (Fig.-6).
Fig.-5: Wooden Moulds for Long Beams and Casting
Fig.-6: Curing of Specimens in Curing Tank.
Impact test
Impact test was conducted for concrete specimen with dimension of 150 mm diameter and 60 mm. The
specimen was placed carefully on the plate of drop weight machine. Iron ball was placed over the
specimen and weight is dropped carefully over the iron ball. This procedure was continued till the
specimen got crack. The number of blows given for the specimen for cracking is noted (Fig.-7).
EXPERIMENTAL
Deflection test for long beams
Specimen details
The cross-sectional dimension of long beams was taken as 150 × 200 and length was take as 1200 mm.
The Fe 415 grade of steel was used for both longitudinal and transverse reinforcements. Table-1 show the
details of minimum longitudinal reinforcements and spacing of transverse reinforcements required and
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actually provided respectively.The beams had been designed and made strong to avoid the failure,
especially at the middle portion. The beam size and length were chosen to ensure that the beams would
fail in deflection and also to test the specimen with the loading frame and the testing facilities available in
the structural laboratory of SRM University.
Fig.-7: Drop Weight Impact Test on Concrete Specimen.
Conduct of experiments
The experiment conducted was explained here in a detailed manner. The beam to be tested was lifted and
kept inside the loading platform of the frame where the steel roller supports were made ready to carry the
beams on both edges to act as simply supported beam. Indian standard medium beam (ISMB) 175 steel
beam was placed parallel and seated on the top surfaces of the beam. Hydraulic jack of 25 T capacities
was placed above the ISMB I75 for application of load. 20 T capacity proving ring was placed above the
hydraulic jack at its centre. The beam was so adjusted that the centres of the proving ring and beams were
in the same line by using plumb-bob. Dial gauge was fixed at the mid-point of the beam portion and
supports are placed 5 cm away from either edge of the beam. The beam loading is done as of two point
loading simply supported beam. Now the arrangement was ready for performing the experiment. The dial
gauges were also set for zero before the start of tests. The load was constantly applied through the
hydraulic jack. ISMB used transferred the load to its edges equally. Beams were allowed and subjected to
a constant increase in the rate of loading till the ultimate load was reached.
RESULTS AND DISCUSSIONS
As a part of experimental investigation, various tests were conducted on the material to test their
properties and in finding out the strength and durability characteristics of the concrete.
Compressive strengths, flexural strengths and tensile strengths were measured using a compressiontesting machine with a maximum capacity of 2000kN. For all tests, each value was taken as the average
of three samples. Test results for conventional concrete and marine algae concrete for 3, 7 and 28 days
curing were tabulated. The following tests were conducted to determine the property of materialsi. Determination of fineness of cement
ii. Determination of normal consistency of cement
iii. Determination of initial setting time of cement
iv. Specific gravity of cement
v. Specific gravity of aggregates
vi. Specific gravity of glass powder
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Compressive Strength
Three numbers of the sample in each of concrete were subjected to compression test using the
compression-testing machine. The result of the average strength of cubes is shown in Table-1. The
comparison of the compressive strength of conventional concrete with that of marine algae concrete is
illustrated using a bar chart in Fig.-8.
Table-1: Compressive strength results for Conventional concrete Vs Marine algae concrete (N/mm2)
Percentage addition of Marine algae
No. of days
2%
5%
8%
10%
Conventional
Concrete
3
10.72
11.73
12.36
9.69
10.23
7
17.86
18.14
19.15
17.34
17.34
28
26.82
27.36
29.24
23.44
26.31
The concrete where marine algae were added to concrete showed an increase in compressive strength.
The strength increased with the number of days of curing. The maximum compressive strength attained
was 29.24 N/mm2 for 8% addition of marine algae to concrete.
Compressive
strength
35
30
25
20
3 days
15
7 days
10
28 days
5
0
CC
2%
5%
8%
10%
Percentage addition of Marine algae
Fig.-8: Comparison of compressive strength of conventional and marine algae concrete
Three numbers of the sample in each of concrete were subjected to testing using the compression-testing
machine. The result of the average strength of cylinders is shown in Table-2 and the comparison of split
tensile strength of conventional concrete with that of marine algae concrete is illustrated using bar chart in
Fig.-9.The strength increased with the number of days of curing. The maximum split tensile strength
attained was 4.6 N/mm2 for 8% addition of marine algae at the end of 28 days.
Table-2: Split tensile strength results for conventional concrete and marine algae concrete
Percentage addition of Marine algae
No. of days
2%
5%
8%
10%
Conventional
Concrete
3
2.4
2.6
2.9
1.9
2.3
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7
3.7
3.9
4.2
3.1
3.6
28
4.1
4.3
4.6
3.4
3.9
Split Tensile strength
(N/mm2)
5
4
3
3 days
7 days
28 days
2
1
0
0%
2%
5%
8%
10%
Percentage addition of Marine algae
Fig.-9: Comparison of tensile strength of conventional Vs marine algae concrete
Flexural Strength
Three numbers of the sample in each of concrete were subjected to testing using the compression-testing
machine. The result of the average strength of flexure beams is shown in Table- 3 and the comparison of
the flexural strength of conventional concrete with that of marine algae concrete is illustrated using line
graph in Fig.-10. The maximum flexural strength attained was 4.7 N/mm2 for 8% addition of marine
algae.
Table-3: Flexural strength results for conventional concrete and marine algae concrete
Flexural Strength (N/mm2)
Description
28 Days
Conventional
3.6 N/mm2
2% addition of marine algae
3.9 N/mm2
5% addition of marine algae
4.3 N/mm2
8% addition of marine algae
4.7 N/mm2
10% addition of marine algae
4.5 N/mm2
Impact strength
The samples in each concrete were subjected to testing using the drop weight impact test. The maximum
number of blows for the first crack and failure was 94 and 96 for 8% addition of marine algae in concrete.
The results of impact strength of concrete are shown in Table-4.
Young’s modulus
The sample in each of concrete was subjected to testing using the compression-testing machine with
fixing the compressometer. The test setup is shown in Fig.-11 and the results of the modulus of elasticity
of concrete are shown in Table-5.
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Flexural Strength
(N/mm²)
5
4
3
2
28 days
1
0
0%
2%
4%
6%
8%
10%
12%
Percentage addition of Marine algae
Fig.-10: Comparison of flexural strength of conventional Vs marine algae concrete
Table-4: Impact strength results for conventional concrete and marine algae concrete
Impact Strength in blows
S.No
Description
1
Initial crack
Failure
Conventional concrete
85
88
2
2% addition of marine algae
87
90
3
5% addition of marine algae
91
92
4
8% addition of marine algae
94
96
5
10% addition of marine algae
88
91
Fig.-11: Young’s modulus setup
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Table-5: Young’s modulus results for conventional concrete and marine algae concrete
Description
Young’s modulus in Mpa
Conventional Concrete
1.34 x 10
2% addition of marine algae
1.42 x 10
5 % addition of marine algae
1.51 x 10
8 % addition of marine algae
1.58 x 10
10 % addition of marine algae
1.46 x 10
4
4
4
4
4
Deflection characteristics
The deflection of the long beams were studied with the help of crack forming with respective the load
applied and the deflection of the beam at the midpoint of the beam. The maximum deflection of the
conventional concrete is 13 mm at 9.6 tonnes of load and for optimum mix the maximum deflection is
7.43 mm at 11.2 tonnes of load.The initial crack in CC beam starts at 2.4 tonnes and for OM beam it starts
at 3.6 tonnes. The CC beam cracks at the shear portion of the beam (at supports), this shear failure was
arrested in the OM beam. The cracks formation was uniform (all over the beam) in the OM beam,
comparatively the CC beams crack formation is not in uniform (more at supports) the specimens with the
crack formation. Fig.-12 shows the specimen under testing and Fig.-13 shows the tested beam specimen.
Fig.-14 show the deflection crurve for both the CC and OM beams.
Fig.-12: Specimen under testing
Fig. -13: Tested beam specimen
CONCLUSION
Following are the important results arrived from this study and they are; The 8% adition of marine algae
in concrete gives the optimum result.The optimum mix gives 20%, 20%, and 25% increase in
compression strength, split tensile strength and flexural strength respectively when compared with
conventional concrete.The optimum mix concrete beam sustains 15% higher load compare to the
conventional concrete beam.
ACKNOWLEDGEMENT
The authors wish to thank the SRM University Management, for their support to complete this study and
those who were directly or indirectly involved in this study.
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Load (kN)
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120
110
100
90
80
70
60
50
40
30
20
10
0
CC
OM
0
1
2
3
4
5
6
7
8
Deflection (mm)
9
10
11
12
13
14
Fig.-14: Load Vs Deflection curve for CC and OM beams
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