E XPERIMENTAL STUDY ON B ACTERIAL C ONCRETE WITH P …€¦ · Bacterial concrete is also known as self-healing concrete or Bio concrete. Bacte rial concrete is specially m ade to

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International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 4, April 2017, pp. 201–209 Article ID: IJCIET_08_04_026 Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=4 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed

EXPERIMENTAL STUDY ON BACTERIAL CONCRETE WITH PARTIAL REPLACEMENT

OF CEMENT BY FLY ASH R. Sri Bhavana

Post Graduate Student, Department of Civil Engineering, KL University, Vaddeswaram, Andhra Pradesh, India

P. Polu Raju Associate Professor, Department of Civil Engineering, KL University, Vaddeswaram, Andhra Pradesh, India

S S Asadi Associate Professor, Department of Civil Engineering, KL University, Vaddeswaram, Andhra Pradesh, India

ABSTRACT One of the most common problems developed in concrete is about cracks. Cracks

are unavoidable in concrete and make the concrete elements weak. Cracks allow water and other salts to seep through them and make the concrete weak and reduce the life of concrete. Corrosion of steel due to salts weakens the reinforced concrete in tension as well. So there is need to develop the methods for curing the cracks and regaining the strength of concrete structures. Currently synthetic polymers can be used to repair the cracks which are harmful to environment which lead to develop biological treatment techniques. In this study, a biological repair technique was used in which bacteria of 105cells/ml were mixed with concrete to heal the cracks. The experiments were carried out to evaluate the effect of Bacillus subtilis on the compressive strength, Tensile strength and Flexural test for 3, 7 and28 days. In addition to above technique fly ash was partially added in the place of cement. The fly ash (0, 10 and 30 %) was added by weight of cement in concrete mix and experiments were carried out. The experimental results show that 10 % fly ash replaced concrete with and without bacteria has more strength when compared to the conventional concrete. Key words: Bacterial Concrete, Fly Ash, Eco-friendly, Bacillus Subtilis.

Cite this Article: R. Sri Bhavana, P. Polu Raju and S S Asadi, Experimental Study on Bacterial Concrete with Partial Replacement of Cement by Fly Ash. International Journal of Civil Engineering and Technology, 8(4), 2017, pp. 201–209. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=4

R. Sri Bhavana, P. Polu Raju and S S Asadi


1. INTRODUCTION Now a day’s world’s main importance is on green and sustainable development of construction industry. Thermal power plants generate large amount of fly ash as a waste material which is a non-decomposed material shows imperative blow on environment and living organisms. Cement was partially replaced with pozzolanic material like fly ash reduces the impact over environment and lead to sustainable development [1, 2]. Cement industries are the major contributors for pollution by releasing CO2. So by partial replacement, cement industries can serve both the purposes of meeting the demands of construction industry and by providing clean and green environment. Moreover there are many advantages on using fly ash as a constituent like reducing heat of hydration in cement which is the main reason for developing cracks in concrete, reduces alkali aggregate reaction and permeability, increased resistance to sulphate attack and corrosion , improves workability which makes concrete mass durable and strong. The requirement of cement is reduced by using fly ash and thus contributes in reducing construction cost. In many developed countries, for durable concrete fly ash is used as essential component. In this study, fly ash is partially replaced in the range of 0 %, 10 % and 30 % by weight of cement in M30 grade of concrete and experiments were conducted and results are drawn. But there is a disadvantage in using fly ash as replacement of cement in concrete because the rate of strength developed is less compared to the ordinary port land cement [1]. Fly ash with other cementing material increases filling ability, passing ability, resistance to segregation [3].

In concrete cracks are most common due to its low tensile strength. High tensile stresses impose deformations due to temperature gradients, reinforcement corrosion, silica reaction, differential settlements and sulphate attack. If the treatment to cracks was not instant and accurate, cracks tend to enlarge rapidly and need costly repairs. Micro-cracks developed in concrete allow liquids and gases through them which eventually lead to damage not only concrete but also the reinforcement gets corroded. Therefore, micro-cracks may lead to structural failure due to failure of both concrete and reinforcement [3, 4]. To sustain and self-strengthening of concrete in harsh environments like sea floors, off shores, highways, sewage pipes, bridges, tunnels and structures for liquid, solid waste carrying toxic and radioactive waste bacteria(bacillus pasteurii) is added [5].

There are many techniques available for the treatment of cracks. Besides, by these techniques there are disadvantageous like different thermal expansion coefficient, environment hazard and health hazard. There is a necessity to develop a new biological technique which is both environmental and health friendly. Therefore, bacterially produced Calcite precipitation (CaCO3) is a biological technique called bio-mineralization is used as self-healing concrete [6,7]. This technique is also used to increase the stiffness of the cracked concrete specimen. Microbial Calcite Precipitation (MICP) technique lead to develop the research in its ability to heal the cracks in concrete, restoration of historical monuments, sand consolidation and other such applications. Use of these MICP techniques and Bio mineralogy lead to invention of new material called Bacterial Concrete [8].

Bacterial concrete is also known as self-healing concrete or Bio concrete. Bacterial concrete is specially made to increase the lifespan of concrete structure by the self-healing action of that concrete. Cracks which appeared on the surface layer of concrete were healed due to calcite crystals produced by bacteria. Compressive strength of the concrete was increased by bacteria such as Bacillus pasteurii, bacillus cohnii, bacillus pseudofirmus, sporosarcina pasteurii and Arthobactercrystallopoietes through their biomass. Corrosion in reinforcement of reinforced concrete can be reduced by Bacillus sp. CT–5. Water and chloride permeability can be reduced by bacteria sporosarcina pasteurii. B.sphaericuscan and Bacillus pasteurii provoke calcite precipitation in the cracks, accumulating compression

Experimental Study on Bacterial Concrete with Partial Replacement of Cement by Fly Ash


strength. There is a reduction in the raise of water by capillary action in microbial concrete as the size of pores is very less compared to the ordinary concrete [9]. Maximum increase in compressive strength is 15.47% observed with 105cell/ml of bacteria [10]. At 35% fly ash bacterial concrete has less deflection, flexural strength, when compared to controlled concrete beams [11]. Bacterial concrete is eco-friendly and it does not show any effect to living beings [12].

In the present work, an experimental work was carried out on bacterial concrete by adding different proportions of fly ash. Tests were conducted to determine strength of both bacterial concrete and normal concrete.

2. RESEARCH SIGNIFICANCE The main significance of the study is to heal the cracks in structural elements by using the bacteria called Bacillus subtilis. Synthetic polymers can also be used to treat the cracks which are harmful to environment, which needs to develop biological treatment techniques. Biological treatment is a type of technique in which bacteria is mixed with conventional concrete to heal the cracks in structural elements. Another important significance is to reduce the production of cement which contributes to air pollution by releasing CO2. Fly ash, which is a thermal power plant wastage having cementitious properties is used as the substitute to cement and helps in reducing the usage of cement.

3. EXPERIMENTAL PROGRAMME

3.1. Material Used In this experiment 43 grade OPC is used. The tests on cement is done as per IS 4031-111988 code. The cement specific gravity was 3.10. Fly ash was used as a pozzolana material in concrete. Fly ashes are generally finer than cement. Fly ash is a by-product obtained from coal. It mainly consists of glassy spherical particles as well as residues of magnetite and hematite, char, and some crystalline phases formed during cooling. Table 1 shows the chemical properties of fly ash.

Table 1 Chemical Properties of Fly Ash

S.No Property % by mass Fly Ash 1 SiO2+Al2O3+Fe2O 92.51 2 SiO2 53.26 3 MgO 0.78 4 Total Alkali (Na2O+K2O) 0.77 5 Sulphuric Anhydride 0.16 6 Al2O3 28.65 7 Fe2O3 5.61

Coarse aggregate is rock which have been squashed and sieved. Coarse aggregate size is normally in the range of 5 to 50mm. The particles of coarse aggregate ought to be more prominent than 4.75mm. Specific gravity of coarse aggregates is 2.80 and bulk density is 1680kg/m3. Generally, the preferred fine aggregate in concrete is river sand which belongs to Zone II. The sand ought to be free from clay and inorganic materials. Specific gravity of coarse aggregates is 2.64 and Bulk density is 1562kg/m3.In this present work, the Bacillus Subtilis bacteria was used. It is a soil bacterium. Whenever this bacteria is amalgated with concrete, it will have the capacity to precipitate calcium carbonate.



3.2. Culturing of Bacillus Subtilis Primarily 1.25g of Nutrient broth (media) was added to a 50 ml of distilled water in a conical flask. Conical flask was covered with a cotton plug and was enclosed with silver foil. Solution was sterilized using an autoclave for about 20 minutes at 121°C and 15lbs. In autoclave, water should be filled up to level 1. After sterilization, the solution was contaminant free and it was in clear orange colour as shown in fig.1 (a). Later, the flasks were opened in lamina air flow chamber and 1mL of the bacteria was added to the solution and was incubated in an orbital shaker witha speed of 125 rpm at 37°C. After 24 hours, it was observed that the colour of bacterial solution changed to whitish yellow turbid as shown in fig.1 (b) which indicates the growth of bacillus subtilis.

(a)…. (b)

Figure 1 (a) Without bacteria (only media), (b) With bacteria

3.3. Concrete Mix Design The selection of specific materials and proportions of concrete to achieve the goal of required properties with most economical use of materials such as strength, durability and workability. In present study mix design of M30 is prepared as per IS: 8112(2013) and proportion is 1:1.5:2.5 having water-cement ratio of 0.45 ratio. Bacillus subtilis bacteria were added to the concrete 105cells/ml to increase the strength and on other hand it reduces the internal cracks the concrete According to IS: 456-2000 the minimum water cement ratio is 0.45. Five different mix proportions are prepared i.e., 0%, 10% and 30% as partial replacement of fine aggregate.

4. RESULTS AND DISCUSSION

4.1. Compression Strength The size of cubical moulds used in compression strength test was 150x150x150mm. Cubes are casted for 0%, 10% and 30% of fly ash with and without bacterial solution. Cubes are tested in compressive testing machine shown in fig.2 after 3, 7 and 28 days curing period. After curing cubes are placed in. Compression strength results are shown in below graphs (Fig.3). From the experimental results, it has been observed that cement replaced with 30% fly ash showed less compressive strength compared to 10% fly ash in both normal and bacterial concrete.



Figure 2 Compressive strength test

Figure 3 (a) Compressive strength results without bacterial solution

Figure 3 (b) Compressive strength results with bacterial solution

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4.2. Tensile Strength Test The sizes of cylindrical moulds are 150mmx300mm for tensile strength test. Cylinders were casted for 0%, 10% and 30% of fly ash with and without bacterial solution. Cubes were tested in tensile strength machine shown in fig.4 after 3, 7 and 28 days curing. Tensile strength results are shown ingraphs (Fig.5).From the experimental results, it has been observed that the bacterial concrete showed more strength than normal concrete.

Figure 4 Split Tensile Strength Test

Figure 5 (a) Tensile strength results without bacterial solution

Figure 5 (b) Tensile strength results without bacterial solution

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4.3. Flexural Strength Test For flexural strength test 500x100x100mm moulds are used. Prisms were casted for 0%, 10% and 30% of fly ash with and without bacterial solution. Cubes were tested in flexural strength machine shown in fig.6 after 3, 7 and 28 days curing. Flexural strength results are given in below graphs.(Fig.7). From the experimental results, it has been observed that cement replaced with 10% of fly ash showed more flexural strength with compared to 30% fly ash in both conventional and bacterial concrete.

Figure 6 Flexural Strength Test

Figure 7 (a) Flexural strength results without bacterial solution

Figure 7 (b) Flexural strength results with bacterial solution

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5. CONCLUSION Bacterial concrete is advantageous than conventional concrete due to its self-healing capacity

and eco-friendly nature.

Concrete with 10% fly ash showed increase in strength and 30% flyash showed decrease in strength when compared to normal concrete.

Calcite precipitate of bacteria indirectly increases the strength of concrete by filling the voids.

The cost of Bacterial concrete is more. So, it is profitable when we go for higher RC structures. By using bacterial concrete the rehabilitation cost can be reduced.

ACKNOWLEDGEMENT I sincerely thankful to Mr. M. Maheshwara Reddy, Associate professor of Biotechnology Department, K L University, for his timely advices in the completion of project. My special thanks to K.S.L. Ramya Krishna, Research scholar of Biotechnology Department, K L University, for her guidance and support in completion of this project.

REFERENCES [1] Patil, S. L., Kale, J. N., Suman, S. “Fly Ash Concrete: A Technical Analysis For

Compressive Strength”. International Journal of Advanced Engineering Research and Studies, 2(1), 2012, pp. 128-129.

[2] Kiran, T. G. S., Ratnam, M. K. M. V. “Fly Ash as a Partial Replacement of Cement in Concrete and Durability Study of Fly Ash in Acidic (H2so4) Environment”. International Journal of Engineering Research and Development, 10(12), 2014, pp. 01-13.

[3] Soundharya, S., Nirmalkumar, K. “Study on the Effect of Calcite-Precipitating Bacteria on Self-Healing Mechanism of Concrete (Review Paper)”. International Journal of Engineering Research & Management Technology, 1(4), 2014, pp. 202-208.

[4] DeBelie, N., DeMuynck, W. “Crack repair in concrete using Biodepositon”, International conference on concrete repair, rehabilitation and retrofitting, 2008, pp. 24-26.

[5] Reddy, B. S., Safiuddin, M. “Mechanical Properties of Bacterial Concrete using Fly Ash as Partial Replacement”. International Journal for Scientific Research & Development, 4(9), 2016, pp. 19-22.

[6] Bang, S. S., Ramakrishnanan, V. “Microbiologically-enhanced crack remediation (MECR)”, The International Symposium on Industrial Application of Microbial Genomes, 2001.

[7] Gollapudi, U.K., Knutson, C.L., Bang, S.S., M.R. Islam, “A new method for controlling leaching through permeable channels”, Chemoshere 30, 1995, pp. 695-705.

[8] M.S. Vekariya, P. Jayeshkumar, “Bacterial Concrete: New Era for Construction Industry”. International Journal of Engineering and Technology, Volume 4 Issue 9 - Sep 2013.

[9] Siddharth, P., Jamnu, M. A. “Effect on Compressive Strength of High Performance Concrete Incorporating Alccofine and Fly Ash”. International Journal of Innovative Research & Development, 3(2), 2014, pp. 124-128.

[10] Manjunath, M., Kadapure, S. A., Kalaje, A. A. “An Experimental Investigation on the Strength and Durability Aspects of Bacterial Concrete with Fly Ash”. Civil and Environmental Research, 6(6), 2014, pp. 61-68.

[11] Naveen, B., Sivakamasundari, S. “Study of Strength Parameters of Bacterial Concrete with Controlled Concrete and Structural Elements made with Concrete Enriched with



Bacteria”. International Conference on Engineering Innovations and solutions, 2016, pp. 53-59.

[12] Ravindranatha, Kannan, N., Likhit, M. “Effect of Bacteria on Partial Replacement of Concrete with Fly-Ash and GGBS”. International Journal of Research in Engineering and Technology, 3(3), 2014, pp. 660-662.

[13] Pappupreethi K, Rajisha Velluva Ammakunnoth and P. Magudeaswaran, Bacterial Concrete: A Review. International Journal of Civil Engineering and Technology, 8(2), 2017, pp. 588–594.

[14] Abhishek Thakur, Akshay Phogat and Khushpreet Singh , Bacterial Concrete and Effect of Different Bacteria on the Strength and Water Absorption Characteristics of Concrete: A Review. International Journal of Civil Engineering and Technology, 7(5), 2016, pp.43–56.

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E XPERIMENTAL STUDY ON B ACTERIAL C ONCRETE WITH P …€¦ · Bacterial concrete is also known as self-healing concrete or Bio concrete. Bacte rial concrete is specially m ade to