Research Paper DURABILITY STUDY ON HVFA BASED BACTERIAL … · 2015-04-13 · Reinforcement corrosion is the most wide spread damage mechanism to which reinforced concrete structures

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Int. J. Struct. & Civil Engg. Res. 2014 M Dhaarani and K Prakash, 2014

DURABILITY STUDY ON HVFA BASED BACTERIALCONCRETE—A LITERATURE STUDY

The aim of this research project is the development of durability of concrete in which integratedbacteria promote self-healing of cracks. Traditional concrete does usually show some self-healing capacity what is due to excess non-hydrated cement particles present in the materialmatrix. These particles can undergo secondary hydration by crack ingress water resulting information of fresh hydration products which can seal or heal smaller cracks. However, theintegration of excess cement in concrete is unwanted from both an economical and environmentalviewpoint. Cement is expensive and moreover, its production contributes significantly to globalatmospheric CO2 emissions. In this study durability of concrete is developed by self-healingsystem in which bacteria converts the metabolic organic compounds to calcite. The result hasbeen expected that the ingress water channeled through freshly formed cracks activate presentbacteria which through metabolic conversion of organic mineral-precursor compounds producecopious amounts of calcite. The self-healing capacity of this system is currently being quantifiedwhat should result in an estimate of the materials durability increase. A self-healing concretemay be beneficial for both economical and environmental reasons. The bacteria based concreteproposed here could substantially reduce maintenance, repair and premature structuredegradation what not only saves money but also reduces atmospheric CO 2 emissionsconsiderably as less cement is needed for this type of self-healing concrete.

Keywords: Bacterial concrete, High volume fly ash, Durability, Water absorption, Sorptivity

1 M.E. Student, Department of Civil Engineering,, Nandha Engineering College, Erode, Tamil Nadu, India.2 Assistant Professor, Department of Civil Engineering,, Nandha Engineering College, Erode, Tamil Nadu, India.

INTRODUCTIONReinforcement corrosion is the most widespread damage mechanism to whichreinforced concrete structures are subjectedwhen they are exposed to aggressiveenvironments. Annual expenditure to repaircorrosion damage are huge to address thisproblem implementation of corrosion

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Int. J. Struct. & Civil Engg. Res. 2014

Research Paper

production should be considered when thereis a risk of reinforced corrosion. The corrosionof structural steel is an electrochemicalprocess that requires the simultaneouspresence of moisture and oxygen. Essentially,the iron in the steel is oxidised to produce rust,which occupies approximately six times thevolume of the original material. The rate at

M Dhaarani1* and K Prakash2

*Corresponding Author: M Dhaarani, [email protected]

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which the corrosion process progressesdepends on a number of factors, but principallythe ‘micro-climate’ immediately surroundingthe structure.

Fresh concrete contains high pH value (12-13) with high alkalinity. This creates a protectivepassive oxide layer over the steel surface,preventing it from corrosion. Gradually, withconstant ingress of oxygen, water, chloridesand carbon dioxide, etc. The pH value of theconcrete reduces to below 8 causing the decayof the protective layer. The Chloride ions alsoattack the passive layer on the metal surfaceexposing it to oxygen and moisture. Once thepassive layer is broken the electrochemicalreaction of corrosion progress unimpeded.

Self-healing property of the concrete hasbeen introduced by the use of microorganism.Different types of Bacillus family bacteria areused for self-healing process of concrete.Bacillus pasturii bacterial properties arestudied and then cultivated for the bioconcrete. Bacteria of different concentrationare mixed with the concrete during mixing. Thebacteria inside the concrete were in deactivestate. Concrete structure is damaged andwater starts to seep through the cracks thatappear in the concrete, the spores of thebacteria germinate on contact with the waterand nutrients. Having been activated, thebacteria start to feed on the calcium lactate.As the bacteria feeds oxygen is consumed andthe soluble calcium lactate is converted toinsoluble limestone.

The limestone solidifies on the crackedsurface, thereby sealing it up. It mimics theprocess by which bone fractures in the humanbody are naturally healed by osteoblast cellsthat mineralize to re-form the bone. The

consumption of oxygen during the bacterialconversion of calcium lactate to limestone hasan additional advantage. Chemical agents likenitrogen, acid etc., are essential in the processof corrosion of steel. When the crack opensthe bacteria consumes oxygen to start itsgrowth and form calcium lactate to fill the smallcracks. Then the bacterial concrete increasesthe durability of concrete structures byprotecting steel from corrosion.

PROPOSED SYSTEMNowadays construction industries are mainlyfocused in the durability aspect of the structure.To overcome this need of contractors, bacteriahave been introduced in the constructionindustry. Bacteria added in to the concrete fillsthe pore spaces inside the concrete. Itincreases the durability of concrete. Bacterialconcrete reduces the repair work whichreduces the cement conception and also HighVolume Fly Ash was replaced to the cement. Itleads to reduce the CO2 emission. Bacterialconcrete make the environment free frompollution. Microscopic analysis is used toevaluate the growth of bacteria inside theconcrete specimens.

The main objective of using High VolumeFly Ash based bacterial concrete is to increasethe durability of concrete. Shrink the productionof cement and emission of CO2 to theatmosphere by increasing the usage ofbacterial concrete. Various tests are carriedout for finding the durability of the castedspecimens.

METHODOLOGYThe methodology of the work starts from thestudy on the properties of the materials and

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healing method for concrete would lead to anew way of designing durable concretestructures, which is beneficial for national andglobal economy.

The “Bacterial Concrete” can be made byembedding bacteria in the concrete that areable to constantly precipitate calcite. Thisphenomenon is called microbiologicallyinduced calcite precipitation. Calciumcarbonate precipitation, a widespreadphenomenon among bacteria, has beeninvestigated due to its wide range of scientificand technological implications. Bacterialconcrete is used to induce CaCO 3

precipitation. The basic principles for thisapplication are that the microbial ureasehydrolyzes urea to produce ammonia andcarbon dioxide, and the ammonia released insurroundings subsequently increases pH,leading to accumulation of insoluble CaCO3.The favorable conditions do not directly existin a concrete but have to be created. How canthe right conditions be created for the bacterianot only to survive in the concrete but also tofeel happy and produce as much calcite asneeded to repair cracks which increases thedurability of concrete.

CULTURE OF BACTERIAInoculation of the BacteriaThe bacteria of prepared cell concentration arethen inoculated in the prepared broth mediumkeeping it inside the Laminar Air flow chamber.The Air flow chamber before initial use needto be cleaned thoroughly with the methylatedspirit and with the UV radiation to kill themicrobes inside if any. The culture wasstreaked on nutrient broth with an inoculatingloop and the slants were incubated at 37 °C.

the past work done from the collection ofliteratures for review. The bacterial propertiesof the fly ash to be used need to be wellstudied.

The materials used for casting thespecimens were properly tested for finding thematerial properties. Depending on the materialtest mix design was prepared and casting hasto be developed. The specimens will be castfor finding the durability of the HVFA bacterialconcrete by the following methods.

• Water Absorption Test

• Sorptivity Test

• Half Cell Potentiometer Test

NEED OF BACTERIAL INCONCRETEConcrete is a material, which is by far the mostused building material in the world. Concretehas a large load bearing capacity forcompression load, but the material is weakintension. That is why steel reinforcement barsare embedded in the material to be able tobuild structures. The steel bars take over theload when the concrete cracks in tension. Theconcrete on other hand protects the steel barsfor attacks from the environment and preventcorrosion to take place. However, the cracksin the concrete form a problem. Here theingress of water and ions take place anddeterioration of the structure starts with thecorrosion of the steel. To increase the durabilityof the structure either the cracks that areformed are repaired later or in the designphase extra reinforcement is placed in thestructure to ensure that the crack width stayswithin a certain limit. For structural reasons thisextra steel has no meaning. A reliable self-

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This ensures the quality of cultured species.Inside the Air flow chamber total backflow ofatmospheric air is stopped in which the entryof harm full microbes can be stopped. Thespirit lamp need to be fired such that the totaltemperature for growth of bacteria can beachieved while transferring it. Keen care mustbe taken throughout the process to ensure thequality by cleanliness. This can be achievedby using the methylated spirit as sanitizer inhands. The face mask should be used toensure quality of cultured bacteria by avoidingthe flow of microbes (if present) into the culture.

IncubationThe bacteria in inoculated broth medium arenow incubated in the incubator at thetemperature of about 34 °C for the period of20 to 24 hours. This is normally done for thegrowth of bacteria, since the growth can onlybe enhanced at this temperature level.

Storage of Stock CultureNow the inoculated broth medium is keptinside the incubator to at least 12 to 14 hoursat normal room temperature to attain the cellgrowth of the bacteria.

Maintenance of Stock CulturesCultures of Bacillus Subtilus were maintainedon nutrient broth culture. After 20 to 24 hoursof growth, slant cultures were preserved underrefrigeration (12 °C) until further use. Sub-culturing was carried out for every 15 hours.Contamination from other bacteria waschecked periodically by streaking on nutrientbroth plates.

Need of Fly Ash in ConcreteNowadays there is a general trend to replacehigher levels of Portland cement with fly ash in

concrete. The increased pressure to usehigher levels of fly ash in concrete systems isdue to the following reasons.

Greater Strength: Fly ash increases instrength over time, continuing to combine withfree lime.

Decreased Permeability: Increased densityand long-term pozzolanic action of fly ash, whichties up free lime, results in fewer bleedchannels and decreases permeability.

Increased Durability: The lower permeabilityof concrete with fly ash also helps keepaggressive compounds on the surface, wheredestructive action is lessened. Fly ash concreteis also more resistant to attack by sulfate, mildacid, and soft (lime hungry) water.

Reduced Alkali Silica Reactivity: Fly ashcombines with alkalis from cement that mightotherwise combine with silica fromaggregates, thereby preventing destructiveexpansion.

Reduced Heat of Hydration: The pozzolanicreaction between fly ash and lime generatesless heat, resulting in reduced thermal crackingwhen fly ash is used to replace a percentageof Portland cement.

Reduced Efflorescence: Fly ash chemicallybinds free lime and salts that can createefflorescence. The lower permeability ofconcrete with fly ash can help to holdefflorescence-producing compounds insidethe concrete.

LITERATURE STUDYVarenyam Achal et al. (2013) microbiallyinduced calcium carbonate precipitation is anaturally occurring biological process that hasvarious applications in remediation and

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restoration of range of building materials. Inthe present study the role of bacteria Bacillussp. on the durability properties and remediationof cracks in cementitious structures werestudied. ‘‘Biocement’’ induced by a Bacillussp. lead to more than 50% reduction in theporosity of mortar specimens, while chloridepermeability of concrete changed from‘‘moderate’’ to ‘‘very low’’ as indicated by rapidchloride permeability test. The bacteriasuccessfully healed the simulated cracks ofdepths including 27.2 mm in cement mortarswith increase in the compressive strength ashigh as 40% of that of control. The resultsclearly showed microbially induced calciumcarbonate precipitation can be applied forvarious building materials for remediation ofcracks and enhancement of durability.

To determine the influence of MICP onmicrostructure both the control and MICPsamples were examined under the ScanningElectron Microscope (SEM). The examinationwas made on the samples collected from themortar cubes tested at 28 days. Noprecipitation was observed in the controlsamples. A clear calcite precipitation wasfound on the crack remediated area in thesamples containing the bacterial cells. Calcitecrystals grew all around the sand particles. Theimprint of rod shaped bacteria was clearlyvisible on the crystals. It may be noted thatBacillus species have a typical rod shapedstructure. SEM indicated that CaCO3 crystalswere precipitated on the cracks. As a result,the sand was cemented by CaCO3 crystalsemulating the cementation effected by cementgrains in conventional concrete. Thecementation resulted in increase in thecompressive strength.

Jonkers (2011), a typical durability-relatedphenomenon in many concrete constructionsis crack formation. While larger cracks hamperstructural integrity, also smaller sub-millimetersized cracks may result in durability problemsas particularly connected cracks increasematrix permeability. Ingress water andchemicals can cause premature matrixdegradation and corrosion of embedded steelreinforcement. As regular manualmaintenance and repair of concreteconstructions is costly and in some cases notat all possible, inclusion of an autonomous selfhealing repair mechanism would be highlybeneficial as it could both reduce maintenanceand increase material durability. In the presentstudy the crack healing capacity of a specificbio-chemical additive, consisting of a mixtureof viable but dormant bacteria and organiccompounds packed in porous expanded clayparticles, was investigated.

Microscopic techniques in combinationwith permeability tests revealed that completehealing of cracks occurred in bacterialconcrete and only partly in control concrete.The mechanism of crack healing in bacterialconcrete presumably occurs through metabolicconversion of calcium lactate to calciumcarbonate what results in crack-sealing.

This bio chemically mediated processresulted in efficient sealing of sub-millimetersized (0.15 mm width) cracks. It is expectedthat further development of this new type ofself-healing concrete will result in a moredurable and moreover sustainable concretewhich will be particularly suited for applicationsin wet environments where reinforcementcorrosion tends to impede durability oftraditional concrete constructions. The

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outcome of this study shows that crack healingof bacterial concrete based on expandedporous clay particles loaded with bacteria andcalcium lactate, i.e. an organic bio-mineralprecursor compound, is much more efficientthan of concrete of the same compositionhowever with empty expanded clay particles.

Yingzi Yang et al. (2011) autogenoushealing of early ages (3 days) ECC damagedby tensile preloading was investigated afterexposure to different conditioning regimes:water/air cycles, water/high temperature aircycles, 90%RH/air cycles, and submersion inwater. Resonant frequency measurements anduniaxial tensile tests were used to assess therate and extent of self-healing. The test resultsshow that ECC, tailored for high tensile ductilityup to several percent and with self-controlledcrack width below 60 ìm, experiencesautogenous healing under environmentalexposures in the presence of water.

However, the recovery for these early agespecimens is not as efficient as the recoveryfor more mature specimen, for the sameamount of pre-damage and exposure to thesame environment. Even so, the self-healingfor these early age specimens demonstrateshigh robustness when the preloading strain islimited to 0.3%. This conclusion is supportedby the evidence of resonant frequency andstiffness recovery of the healed ECCmaterials.

The study presents the findings of aninvestigation into the autogenous healing ofECC subjected to different environmentalexposure regimes, after deliberate damageby preloading in direct tension at 3 days of age.The inherent tight crack width of ECC, less than

60 m, leads ECC to display robust self-healing properties at early ages withappropriate environmental exposure. Self-healed ECC shows substantial RF recoveryas well as recovery of uniaxial tensile stiffness.

The self-healing of micro cracks in ECC isexpected to overcome the problem of earlyage cracking in high performance concretematerials for infrastructures exposed to water,e.g., transportation infrastructure such asroadways and bridges or in water-retainingstructures. Thus self-healing ECC shouldmaintain stiffness, strength and ductility evenwhen subjected to damaging loads at an earlyage, especially when the damage level islimited to below 0.3%.

Willem De Muynck et al. (2008) surfacetreatments play an important role in theprotection of construction materials from theingress of water and other deleterioussubstances. Due to the negative side-effectsof some of the conventional techniques,bacterial induced carbonate mineralizationhas been proposed as a novel andenvironmental friendly strategy for theprotection of stone and mortar. This paperreports the effects of bacterial CaCO3

precipitation on parameters affecting thedurability of concrete and mortar. Pure andmixed cultures of ureolytic bacteria werecompared for their effectiveness in relation toconventional surface treatments. Bacterialdeposition of a layer of calcite on the surfaceof the specimens resulted in a decrease ofcapillary water uptake and permeabilitytowards gas.

Bacterial treatment resulted in a limitedchange of the chromatic aspect of mortar andconcrete surfaces. The type of bacterial culture

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and medium composition had a profoundimpact on CaCO3 crystal morphology. The useof pure cultures resulted in a more pronounceddecrease in uptake of water, respectively lesspronounced change in the chromatic aspect,compared to the use of mixed ureolytic culturesas a paste.

The results obtained with cultures of thespecies Bacillus sphaericus were comparableto the ones obtained with conventional waterrepellents. Deposition of a layer of calcite onthe surface of the specimens resulted in adecrease of capillary suction and a decreasein gas permeability. Treatment with bacteriaresulted in a limited change of the chromaticaspect of mortar and concrete surfaces. Thetype of bacterial culture and mediumcomposition had a profound impact on CaCO3

crystal morphology. The use of pure culturesresulted in a more pronounced decrease inuptake of water, respectively, less pronouncedchange in the chromatic aspect, compared tothe use of mixed ureolytic cultures as a paste.

MATERIALS AND METHODSMaterials and MixingOrdinary Portland cement of 53 grade withstandard consistency of 30% and specificgravity of 3.15. Fly ash of class F with specificgravity of 2.31 will be used. Fine aggregateconfirming to IS: 383-1970 with 2.42 specificgravity and coarse aggregate of 20 mm size,0.55% water absorption and specific gravityof 2.78 will be used for preparation of concretespecimens. Micro organism of Bacillussubtilus is cultured and added to the waterduring mixing of concrete in three differentconcentrations like 105 cells/liter, 106 cells/literand 107 cells/liter. M40 grade mix will be used

for the specimens and 40% of cement isreplaced by Fly ash.

Methods of TestingConvention concrete specimens with HVFAwill be prepared for determining themechanical properties and durability of theconcrete. Bacterial concrete with differentconcentration will be prepared for finding themechanical properties and durability of theconcrete.

Mechanical PropertiesMechanical properties like compression test,split tensile strength and flexural strength willbe carried out. Cube specimens of size 150mm x 150 mm x 150 mm, Cylinder specimensof 150 mm diameter and 300 heights andprism of size 500 mm x 100 mm x 100 mm willbe casted for f inding the mechanicalproperties like compression, split tensile andflexural strength respectively.

Durability TestsStandard cubes of size 150 mm x 150 mm x150 mm will be casted for water absorptiontest and sorptivity test. The beam element ofsize 1.0 m x 0.19 m x 0.19 m will be preparedfinding the corrosion of the steelreinforcements embedded in the concrete.

EXPECTED RESULTSMicroorganism inside the concrete fills thespores inside the specimens. Reduction ofpore sizes increases the mechanical strengthof the concrete. Depending on theconcentration strength also increasedgradually. Bacteria inside the concrete fill theair voids so water absorption percentage,Sorptivity coefficient value will be reduced andit increases the durability of the concrete.

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CONCLUSIONThe above said test is to be conducted inphase-II project work.

Here, we are expecting the durability of theconcrete will increase with the involvement ofbacteria (in form of liquid) and flyash.Specimens are now ready for the furtherprocess of durability test.

REFERENCES1. Bouzoubaa N, Zhang M H and Malhotra

V M (2000), “Laboratory-Produced High-Volume Fly Ash Blended CementsCompressive Strength and Resistance tothe Chloride-Ion Penetration of Concrete”,Journal of Cement and ConcreteResearch, Vol. 30, pp. 1037-1046.

2. Chindaprasirt P, Chotithanorm C, Cao HT and Sirivivatnanon V (2007), “Influenceof Fly Ash Fineness on the ChloridePenetration of Concrete”, Journal ofConstruction and Building Materials,Vol. 21, pp. 356-361.

3. Jonkers H M (2011), “Bacteria BasedSelf-Healing Concrete”, Journal ofHERON, Vol. 56, pp. 1-12.

4. Kim Van Tittelboom, Nele De Belie,Willem De Muynck and Willy Verstraete(2010), “Use of Bacteria to RepairCracks in Concrete”, Journal of Cementand Concrete Research , Vol. 40,pp. 157-166.

5. Mayur Shantilal Vekariya andJayeshkumar Pitroda (2013), “BacterialConcrete: New Era for ConstructionIndustry”, International Journal ofEngineering Trends and Technology,Vol. 4, pp. 4128-4137.

6. Mustafa S Ahmaran and Victor C L(2008), “Durability of MechanicallyLoaded Engineered Cementit iousComposites Under Highly AlkalineEnvironments”, Journal of Cementand Concrete Composites, Vol. 30,pp. 72-81.

7. Navneet Chahal and Rafat Siddique(2013), “Permeation Properties ofConcrete Made with Fly Ash and SilicaFume: Influence of Ureolytic Bacteria”,Journal of Construction and BuildingMaterials, Vol. 49, pp. 161-174.

8. Rafat Siddique and Navneet Kaur Chahal(2011), “Effect of Ureolytic Bacteria onConcrete Properties”, Journal ofConstruction and Building Materials,Vol. 25, pp. 3791-3801.

9. Seshagiri Rao M V, Srinivasa Reddy V,Hafsa M, Veena P and Anusha P (2013),“Bioengineered Concrete—ASustainable Self-Healing ConstructionMaterial”, Research Journal ofEngineering Sciences, Vol. 2, pp. 45-51.

10. Sunil Pratap Reddy S, Seshagiri Raob MV, Aparnac P and Sasikalac Ch (2010),“Performance of Standard GradeBacterial (Bacillus Subtilis) Concrete”,Asian Journal of Civil Engineering(Building & Housing), Vol. 11, pp. 43-55.

11. Vanita Aggarwal, Gupta S M andSachdeva S N (2010), “ConcreteDurability Through High Volume Fly AshConcrete (HVFC) A Literature Review”,International Journal of EngineeringScience and Technology, Vol. 2, No. 9,pp. 4473-4477.

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12. Varenyam Achal, Abhijeet Mukerjee andSudhakara Reddy M (2013), “BiogenicTreatment Improves the Durability andRemediates the Cracks of ConcreteStructures”, Journal of Construction andBuilding Materials, Vol. 48, pp. 1-5.

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Research Paper DURABILITY STUDY ON HVFA BASED BACTERIAL … · 2015-04-13 · Reinforcement corrosion is the most wide spread damage mechanism to which reinforced concrete structures