The Flexural Strength of Bacteria-Based Concrete for Sustainable

Materials

Mutia Gina Savira

, Ujang Ruslan

, Keryanti

and Luthfi Muhammad Mauludin

Civil Engineering Department, Politeknik Negeri Bandung, Jl. Gegerkalong Hilir, Bandung Barat, Indonesia

Chemical Engineering Department, Politeknik Negeri Bandung, Jl. Gegerkalong Hilir, Bandung Barat, Indonesia

Keywords: Flexural Strength, Bacillus Megaterium, Fly Ash, Cracks.

Abstract: Concrete is the most popular material used in construction. In fact, concrete lies in its resistance to

compressive forces. However, the drawback of the concrete materials is weak in tension. Because of its

weakness, it can cause cracks in the concrete. One way to handle cracks in the concrete is to make bacteria-

based concrete. In this research, the type of bacteria used in concrete mixing is Bacillus megaterium. The

purpose of this research is to study the effect of Bacillus megaterium on the flexural strength of concrete. The

bacteria proportions of 1% and 2%, which are adopted in this study, were combined with fly ash as an additive

material. The specimens were casted into beam molds sized (500x100x100) mm and then tested under a three-

point bending machine to observe its bending capacity. The flexural strength of bacteria-based concrete was

observed for some periods, namely 14 days and 28 days. From this research, it can be concluded that the

flexural strength of bacteria-based concrete was raised up to 14,64% compared to virgin concrete.

1 INTRODUCTION

In infrastructure, concrete structures are the most

popular structures. The advantage of a concrete

structure is its resistance to compressive forces. This

material is widely used because of its strength and

durability (Bashir et al., 2016). On the other hand, the

weakness of the concrete structure is weak tension.

From this weakness, concrete is quite sensitive to

cracking which can compromise the durability of the

concrete structure as a whole (Luthfi Muhammad

Mauludin & Rabczuk, 2021) so it can cause cracks in

the concrete. Starting from a small crack, then it

becomes a medium crack and finally into a large

crack. If small cracks are not treated immediately, it

will cause larger cracks so that it can trigger cavities

that can make the reinforcing steel corrosive. If

repairs are not immediately carried out, it will result

in structural failure (collapse) and can also threaten

human life.

Cracks in concrete must be carefully monitored

and periodically repaired for ensuring durability and

safety (Luthfi M. Mauludin et al., 2018). Small cracks

(microcracks) such as the one in that develop in the

concrete due to unbalanced (balanced) tensile forces.

Therefore, there is a self-healing concrete technology

with a mechanism to independently repair the cracked

part without human intervention in its maintenance

(Mauludin et al., 2018).The crack trajectory is highly

dependent on the inclusions in the material (Luthfi

Muhammad Mauludin & Rendragraha, 2022).

Because of that, the maintenance and repairs on

concrete structures are needed periodically according

to their needs and conditions. Meanwhile, the cost of

maintaining and repairing concrete structures is quite

high, Especially the crack that is located in difficult

area, such as in water or on the ground.

To solve this problem, bacteria-based concrete is

an alternative to many other conventional

technologies because they are environmentally

friendly, and have the ability to act as self-healing

agents (Tiwary, 2021). The active bacterial cells able

to convert the calcium lactate (CaC6H10O6) into

CaCO3 (Calcium Carbonate) using oxygen and water

(Tziviloglou et al., 2016).

In this study, a test will be carried out in the form

of the application of Bacillus megaterium bacteria

and calcium lactate which is inserted into the concrete

mixture.

986

Savira, M., Ruslan, U., Keryanti, . and Mauludin, L.

The Flexural Strength of Bacteria-Based Concrete for Sustainable Mater ials.

DOI: 10.5220/0011982900003575

In Proceedings of the 5th International Conference on Applied Science and Technology on Engineering Science (iCAST-ES 2022), pages 986-991

ISBN: 978-989-758-619-4; ISSN: 2975-8246

2 LITERATURE REVIEW

Bacterial Concrete or Bacterial-Based Concrete is

intelligent concrete that exhibits human-like self-

healing characteristics that increase the strength of the

structure, especially under stress, and other

advantages such as the overall service life of the

structure were found to be increased, the effective

utilization of bacteria from corrosion, due to the

presence of water vapor generated used as a catalyst

to continuously maintain the quality of concrete, self-

healing concrete is better than traditional concrete

because of its environmentally friendly nature

(Ghodke & Mote, 2018).

Some researchers have conducted several

methods of self-healing concrete with using many

healing agents. Namely as follows.

a. Mauludin et al., 2018 in a journal article entitled

Computational modeling of fracture in

encapsulation-based self-healing concrete using

cohesive elements examined self-healing

concrete using computational methods carried

out with Abaqus, Python and Matlab software.

b. Rahmawan et al., 2021, in his journal entitled

Application of Bacteria as Self-Healing Agents

in Concrete, discuss the comparison of various

types of bacteria.

c. Gruyaert et al., 2016, in their journal entitled

Capsules with evolving brittleness to resist the

preparation of self-healing concrete. This

journal discusses the types of capsule shells.

Using polymer type capsules.

In previous studies, tests have been carried out

using encapsulated techniques both computationally

and experimentally, then there are studies using the

overall base material in the form of geopolymers and

there are studies that focus on the levels of Bacillus

megaterium bacteria which are effective for

increasing the compressive strength of concrete.

3 MATERIALS

3.1 Bacteria

The type of bacteria used in this research is namely

Bacillus megaterium. Bacillus bacteria can produce

as fillers for binding materials to shrink the capillary

pores of concrete to increase its strength and

durability (Andalib et al., 2016).

Bacillus megaterium is an organism that has

following characteristics: not filamentous, gram

positive, rod-shaped, produces endospores, catalase

positive, aerobic, nitrite negative and VP negative.

This kind of bacteris have endospore in the middle

of its cell. Bacillus bacteria have a positive effect on

the compressive strength of concrete and flexural

strength compared to conventional samples, and can

reduce water absorption (permeability) (Stanaszek-

Tomal, 2020).

The following is the classification of Bacillus

megaterium as listed in Figure 1:

Kingdom : Bacteria

Filum : Firmicutes

Kelas : Bacilli

Ordo : Bacillales

Famili : Bacillaceae

Genus : Bacillus

Spesies : Bacillus megaterium

Source: (Jayanti rusyda, 2014)

Figure 1: Bacillus megaterium Bacteria.

3.2 Fly Ash

Fly ash is used to stabilize the temperature of cement

so as not to harm the microbes inside. This type of

geopolymer has several advantages: more

environmentally friendly (in the manufacturing

process without releasing CO2 emissions into the

atmosphere), high workability (easy to flow or self-

leveling), more resistant to chemical attack (sulphate,

acid, and chloride), and more resistant to high

temperatures. Therefore, other substances are needed

such as Sodium Hydroxide (NaOH) and Sodium

Silica (Na2SiO3) (Rizal et al., 2020).

The type of fly ash is grade 6 or class F which is

an active type of fly ash, it can be used as a binder not

only as a filler as listed in Figure 1.

4 METHODOLOGY

To carry out this research, good planning is needed so

that in its implementation it can run effectively and

efficiently. The type of this reasearch is experimental.

The Flexural Strength of Bacteria-Based Concrete for Sustainable Materials

987

Figure 2: Fly Ash.

The reseacrh was begun with studying the

previous studies on bacteria-based concrete. The

design the concrete with f’c 20 MPa specification,

was used ACI 211.1-1991 standard for 36 speciments.

The next step is testing the concrete materials. The

tests are Cement Specific Gravity (SNI 1527-2531-

1991), Cement Grain Fineness (SNI 03-1969/1970 –

ASTM C.127/128-95), Coarse Aggregate Gradation

Testing (SNI 03-1968-1990/ BS 410-1986),

Aggregate Moisture Testing (SNI-03-1971-1990),

Sludge Content Testing Passed through Sieve 200

(SNI 03-4142-1996/ ASTM C.117-95), and Organic

Fine Aggregate Testing (ASTM C.33-95).

Figure 3: The Preparation of Concrete Materials

After the materials test and mix design had been

done, the next step are preparation of the bacteria,

concrete materials as listed in Figure 3 and making

the speciments.

Figure 4: Bacteria Sample.

After prepared the media (nutrient agar) was

prepared with using autoclaved at 120°C for 15

minutes, then the media kept in the incubator at 35°C

and the colony of bacteria will growing there. After 3

days, the colony of bacteria will be moved into a

nutrient broth then shaked in 5 days along as listed in

Figure 4.

Figure 5: Concrete Casting Process.

To perform the flexural strength test, the bacterial

sample mixed with the concrete. When bacterial

concrete was casted, bacteria sample was added to the

water in ratio 1:100 (1% proportion) and 2:100 (2%

proportion). To cast the virgin concrete (conventional

concrete), no bacteria was added and no other

treatment was applied. The concrete casting process

is as listed in Figure 5.

Figure 6: The Bending Machine.

To do Flexural Strength Test, he standard that

used in this test is ASTM C.293. Flexural strength test

was performed on beam of size 100 mm × 100 mm ×

500 mm with three point bending. The testing was

conduct in 14 days and 28 days. Then tested under

three point bending machine as listed in Figure 6.

5 RESULT AND DISCUSSION

The following are the result of flexural strength in 14,

and 28 days, flexural strength values of virgin

concrete, Bacteria-based concrete (BBC) which

iCAST-ES 2022 - International Conference on Applied Science and Technology on Engineering Science

988

proportion are 1% and 2%, concrete with fly ash 2%,

then Bacteria-based Concrete with fly ash 2%

containing 1% and 2% bacteria proportions were

tested.

5.1 The Effect of Bacteria in

Conventional Concrete

After tested in 14 dyas of the specimens, there are a

trend increasing between the bacteria based-concrete

and virgin concrete the virgin concrete, concrete with

bacteria-based concrete 1% and bacteria-based

concrete 2% were tested and the result is increased

between the virgin concrete and the bacteria-based

concrete 2% as listed in Figure 7. The increasing is up

to 14,64%.

Figure 7: Graph Showing The Flexural Strength in 14 and

28 Days.

Figure 8: Graph Showing The Comparing Flexural Strength

in 14 and 28 Days.

Then, after 28 days, the virgin concrete, concrete with

fly ash 2%, bacteria-based concrete 1% and bacteria-

based concrete 2% were tested and the result is

increased between the virgin concrete and the

bacteria-based concrete 2% as listed in Figure 7. The

increasing is up to 4,44 for BBC 2 % and 4,64 for

BCC 1% compared with the virgin concrete as liested

in Figure 7.

So, the comparison between the 14 and 28 is listed in

. It shows that the result of an increasing trend of

bacteria-based concrete with a significant increase

between the virgin and the bacteris-based concrete

which bacteria proportion that the highest flexural

strength is 2% bacteria proportion.

5.2 The Effect of Bacteria in Fly Ash

Concrete

Figure 9: Graph Showing The Comparing Flexural Strength

of Virgin Concrete and Fly Ash Concrete in 14 and 28 Days.

Then, after 28 days, the virgin concrete, concrete with

fly ash 2%, bacteria-based concrete 1% and bacteria-

based concrete 2% were tested. And the Figure 9

shows that adding a fly ash in 2% could not increase

the flexural strength of virgin concrete.

The flexural test result in 14 days as listed in

Figure 10, is increased between the concrete + Fly

Ash 2% and the bacteria-based concrete 2%. The

increasing is up to 10,54% for BBC 2 % and for BCC

1%, there was degression into 8,13% compared with

the concrete+ Fly Ash 2%.

The following is the flexural result of adding 2%

fly ash into bacteria-based concrete 1% and bacteria-

based concrete 2% in 28 days as listed in Figure 10.

The comparison between 1% and 2% bacteria

proportion in 28 days was variated degression

between the concrete + Fly Ash 2%. For the BBC

1%+Fly Ash 2% the degression was 7,79% and for

the BBC 2%+Fly Ash 2% the degression was 7,79%

compared with the concrete + Fly Ash 2%.

3,205

3,365

3,674

3,729

3,824

3,903

2,8

3,3

3,8

4,3

Virgin

Concrete

BBC1% BBC2%

FlexuralStrength(MPa)

Comparisonbetween14and28days

FlexuralStrength(MPa)in14days

FlexuralStrength(MPa)in28days

3,205

3,729

3,183

3,453

3,1

3,2

3,3

3,4

3,5

3,6

3,7

3,8

FlexuralStrength

(MPa)in14days

FlexuralStrength

(MPa)in28days

FlexuralStrengthofVirginCncreteandFly

AshConcrete

VirginConcrete Concrete+FlyAsh2%

The Flexural Strength of Bacteria-Based Concrete for Sustainable Materials

989

Figure 10: Graph Showing The Flexural Strength of fly ash

2% concrete, fly ash 2% + bacteria 1% concrete , and fly

ash 2% + bacteria 2% concrete in 28 Days.

5.2 The Specimens After Flexural

Strength in 14 Days and 28 Days

The following are the condition of specimens after

flexural strength test as listed to Figure 11 and Figure

12.

Figure 11: The Specimens After Flexural Strength Testing

Conditiosns.

Figure 12: The Crack Pattern of Specimens After Flexural

Testing.

6 CONCLUSION

The goal of this research was to see how bacteria

(Bacillus megaterium) affected the flexural strength,

of conventional (virgin concrete) and bacteria-based

concrete. The results of this study can be concluded

as follows:

 Based on the test results, this bacteria-based

cocrete is a promosing material, by using

bacteria-based concrete could reduce to use

cement materials and forthemore it will be a

sustanable materials.

 The concrete samples were evaluated for

flexural strength in both conventional and

bacterial concrete. By applicated the bacteria in

concrte, it was positively affected to increase the

flexural strength compared with the virgin

concrete. The higher the proportion of bacteria,

it can make the higher flexural strength. In

comparison to ordinary concrete, the flexural

strength of bacillus megaterium as bacteria-

based concrete by 14,64% while the fexural

sstrength of adding fly ash 2% is 8,91%.

 By adding fly ash 2% and tested in 14 and 28

days, it doesn’t shows that the result is increased

the mechanical properties compared with the fly

ash concrete + bacteria. Due to the fly ash as an

additive could make another condition of

bacteria, so it could not be affected for the

flexural strength.

ACKNOWLEDGEMENTS

This research was funded by Politeknik Negeri

Bandung (POLBAN) through Post Graduate

Research Grant Program (PPS) in 2022.

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