Report 456.docx

SELF- HEALING CONCRETE

CHAPTER 1

INTRODUCTION 1.1 Definition: Self -Healing Concrete The Self-healing Concrete is one that senses its crack formation and reacts to cure itself without human intervention. Self-healing concrete is a product that will biologically produce limestone to heal cracks that appear on the surface of concrete structures. Specially selected types of the bacteria Bacillus sphaericus, is added to the ingredients of the concrete when it is being mixed. These self-healing agents can lie dormant within the concrete for up to 200 years.

1.2 Bacterial Concrete The “Bacterial Concrete” can be made by embedding bacteria in the concrete that are able to constantly precipitate calcite. Bacillus Sphaericus is a soil bacterium, can continuously precipitate a new highly impermeable calcite layer over the surface of an already existing concrete layer. The favorable conditions do not directly exist in a concrete but have to be created. A Main part of the research will focus on this topic. Tests are conducted to study the mechanical properties of the above concrete with various percentages of Bacteria. The tests carried out are Compressive strength test, Split Tensile strength test.

1.3 Mechanisms Some possible mechanisms for Self-healing are: 1. Formation of material like calcite. 2. Blocking of the path by sedimentation of particles. 3. Continued hydration of cement particles. 4. Swelling of the surrounding cement matrix

1.4 Objects of Biological Approach To develop methods to enhance durability of concrete by adding bacteria. To regain the maximum strength of concrete after cracking rectification. To develop methods of concrete after cracking rectification.

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1.5 Bio-mineralization Natural processes such as weathering, faults, land subsidence, earthquakes and human activities create fractures and fissures in concrete structures and historical stone monuments. These fractures and fissures are detrimental since they can reduce the service life of the structure. In the case of 20 monuments and buildings of historic importance, these cracks tend to disfigure and destroy the structure. Use of bacterial concrete for remediating these structures will reduce the crack width and increase the strength of the structure. Therefore a novel technique for remediating damaged structural formations has been developed by employing a selective microbial plugging process, in which microbial metabolic activities promote calcium carbonate (calcite) precipitation.(Meldrum F.C.2003,stocks et al,1999). The technique is called “Microbiologically Enhanced Crack Remediation (MECR). This technique comes under a broader category of science called “Biomineralization”. It is a process by which living organism form inorganic solids. Bacterial deposition of a layer of calcite on the surface of the specimens resulted in a decrease of capillary water uptake and permeability towards gas. This bacterial treatment resulted in a limited change of the chromatic aspect of mortar and concrete surface. The type of bacterial culture and medium composition had a profound impact on CaCo3 crystal morphology.

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SELF- HEALING CONCRETE

CHAPTER 2

MATERIALS & METHODOLOGY 2.1 Materials Used The ordinary concrete used in the test program consisted of cementing materials, mineral aggregates and corrosion inhibitor with the following specifications:  Ordinary Portland Cement (53 Grade)  Graded fine aggregates.  Graded coarse aggregates.  Water.  Bacteria – Bacillus Sphaericus

2.1.1

Ordinary Portland Cement

The cement is a binding material. It conforms to IS456-2000-53 grade. It consists of grinding the raw materials, mixing them intimately in certain proportion depending upon their purity and composition and burning them in a kiln at a temperature of about 1300 – 1500 degree centigrade at which temperature, the material Center and partially fuses to form modular chapped clinker. The clinker is cooled and ground to a fine powder with addition of 2 to 3% of gypsum the product formed by using this procedure Portland cement. Of all the materials that influence the behavior of concrete, cement is the most important constituent, because it is 11 used to bind sand and aggregate and it resists atmospheric action. Portland cement is a general term used to describe hydraulic cement.

Fig 1 Cement

2.1.2

Graded Fine Aggregates

The materials smaller than 4.75 mm size is called fine aggregates. Natural sand is generally used as fine aggregate. In this experimental work replacement of river sand by DEPARTMENT OF CIVIL ENGINEERING,AGMRCET VARUR

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quarry waste (fineness modulus of crushed sand equal to 3.2) conforming to grading Zone III of IS – 383 – 1970 was used as fine aggregates.

Fig.2 Fine Aggregate

2.1.3

Graded Coarse Aggregate

Locally available well graded granite aggregates of normal size greater than 4.75 mm and less than 16mm having fineness modulus of 2.72 was used as coarse aggregates.

Fig.3 Coarse Aggregate

2.1.4

Water

Potable water has been used for casting concrete specimens. The water is free from oils, acids, and alkalis and has a water-soluble Chloride content of 140 mg/lit. As per IS 456 – 2000, the permissible limit for chloride is 500 mg/lit for reinforced concrete; hence the amount of chloride present is very less than the permissible limit.

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Fig.4 Water

2.1.5

Bacteria Bacillus sphaericus is an obligate aerobe bacterium used as a larvicide for

mosquito control. It forms spherical endospores. Bacillus sphaericus is a gram positive bacteria, with rod shaped cells that form chains-Medium-sized, smooth colonies with an entire margin and also Rod-shaped cells.Gram-variable, large, spore-forming rods with a diameter < 0.9μm. Catalase -positive. Lecithinasenegative. Does not attack sugars. Growthing range of Temperature: 37oc Optimum Temperature- 35-37oc

Fig.5 Bacteria

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2.2 Methodology IS CODE REFERENCE AND USAGE

MIX DESIGN OF M20

TESTING OF MATERIALS

WORKABILITY TEST

MIX PROPORTION

IDENTIFICATION OF BACTERIA

INTRODUCTION OF BACTERIA

PREPARATION OF BACTERIA

MIXING AND COMPACTING

CURING

IMPLEMENTATION AND TESTING

RESULTS

Fig.6 Methodology Chart

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2.2.1 Preparation of Bacteria 1. Mixing of Bacteria Luria

Berta-powder

peptone(3gms)+yeast

form

(6.75gms)+500ml

extract(1.5gms)+Beef

of

extract(1.5gms)

distilled +sodium

water

+

chloride

(3gms/100ml) +1Loop of Bacteria (gel medium) = Incubator 37 °C. 2. Preparation of Nutrient Agar Bacteriological media came an wide range of types. Nutrient Agar is a complex medium. Nutrient Agar contains beef extract (0.3%), peptone (0.5%), and Agar (1.5%) in water. Beef extract is prepared as dehydrated form of autolysed beef and is supplied in the form of paste. Pepton is casein (milk protein) that has been digested with the enzyme pepsin. Peptone is dehydrated and supplied as a powder. Peptone and Beef extract contains a mixture of amino acids and peptides. Beef extract also contains water soluble digest products of all other macro molecules (nucleic acids, fats, polysaccharides) as well as vitamins trace minerals. Agar is purified from red algae in which it is an accessory polysaccharide (polyalacturonic acid) of their cell walls. Agar is added to microbiological media only as a solidification agent. Agar for most purposes has no nutrient value. Agar is an excellent solidification agent because it dissolves at near boiling point solidifier at 45ºC. Thus one can prepare molten (liquid) agar at 45ºC, mix cells with it, then allow it to solidify thereby trapping living cells. Below 45ºC agar is a solid and remains so as the temperature is raised melting only when greater than 95oC is obtained. 3. Processing of Bacteria In this method Bacteria are added during casting of concrete. The amount of Bacteria added in the range of 10ml & 15 ml/m3 of concrete. Concrete could soon be healing its own hairline cracking. Holes of wet concrete are healed. Combined calcium with oxygen and carbon di oxide to form calcite is essential for healing tiny cracks which arrest the seepage of water.

Fig.7 Growth of Bacteria

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The technique of using soil bacterium is highly desirable because the mineral precipitation induced as a result of microbial activities, is pollution free and natural. Bacillus spharecius was yet another partially characterized species, having the capability of precipitating calcium carbonate.Its Far better would be to use bacillus sphaericus as a material that heals itself just as the cell divines and produces a visible mass. The colony isolated from other colonies, isolated colonies are assumed to be pure culture. 4. Culturing and Isolation Microorganism must have a constant nutrient supply if they are to survive.  Media may be liquid (broth) or solid (agar). Any desired nutrients may be in corporate in to the broth (or) agar to grow bacteria.  Organism grown in broth cultures causes turbidity, (or) cloudiness, in the broth. On agar, masses of cells known as colonies appear after a period of incusation certain separated on agar so that as the cell divines and produces a visible mass.  The colony isolated from other colonies, isolated colonies are assumed to be pure culture. 5. Ability of the Bacterial Concrete to Repair the Cracks Both attention will be given on closure of cracks (blocking the path for ingress of water and ions) and on regaining mechanical properties. Cracks in concrete specimen subjected to various loading situations will be investigated before and after the healing. For this impregnation techniques and SEM will be applied. (Scanning electron microscope). On the other hand the micro-organisms such as bacteria, cyono bacteria, algae, lichens, yeasts, fungi and mosses etc. Which are omnipresent and omnipotent are responsible for metabolism action that results in a microbial deposition of a protective CaCO3 layer. Aiso, this process results in re-establishment of the cohesion b\n particles of mineral building materials and protects against further decay of stone material. To prove the positive effects of microbial CaCO3 precipitation. Theincrease in porosity in concrete leads to increase in capillary water uptake, increase in gas permeability along with higher carbonation rate, high chloride migration and freeze-thaw damage.

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6. Processing of Bacteria Concrete could soon be healing its own hairline cracking. Holes and pores of wet concrete are healed. Combined calcium with oxygen and carbon di oxide to form calcite is essential for healing tiny cracks which arrest the seepage of water.

2.3 Experimental Study 2.3.1 Process of Manufacture of Concrete Production of quality concrete requires meticulous care exercised at every stage of manufacture of concrete. If meticulous care is not exercised, and good rules are not observed, the resultant concrete is going to be of bad concrete. Therefore, it is necessary for us to know what are the good rules to be followed in each stage of manufacture of concrete for producing good quality concrete. The various stages of manufacture of concrete are: 1 Batching 2 Mixing 3 Placing 4 Compacting 5 Curing 1 Weigh Batching Weigh batching is the correct method of measuring the materials. For important concrete, invariably, weigh batching system should be adopted. Use of weight system in batching, facilitates accuracy, flexibility and simplicity. Different types of weigh batchers are available, the particular type to be used, depends upon the nature of job. When weigh batching is adopted, the measurement of water must be done accurately using measuring jars. 2 Hand Mixing Hand mixing is practiced for small scale concrete works. Hand mixing should be done over an impervious concrete or brick floor of sufficiently large size to take one bag of cement. Spread out the measured quantity of coarse aggregate and fine aggregate DEPARTMENT OF CIVIL ENGINEERING,AGMRCET VARUR

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in alternate layers. Pour the cement on the top of it, and mix them dry by shovel, turning the mixture over and over again until uniformity of color is achieved. This uniform mixture is spread out in a thickness of about 20 cm. This operation is continued till such a good time a good uniform, homogenous concrete is obtained. It is a particular importance to see that the water is not poured but it is only sprinkled. Water in a small quantity should be added towards the end of the mixing to get the just required consistency. At that stage, even a small quantity of water makes difference. After that the bacteria medium is sprinkled over the concrete mixture. 3 Placing It is not enough that a concrete mix correctly designed, batched, mixed, it is of utmost importance that the concrete must be placed in systematic manner to yield optimum results. The precautions to be taken and methods adopted while placing concrete in the moulds. 4 Hand Compaction Hand compaction of concrete is adopted in case of small concrete works. Sometimes ,this method is also applied in such situation, where a large quantity of reinforcement is used, which cannot be normally compacted by mechanical means. Hand compaction consists of rodding, ramming or tamping. When hand compaction is adopted, the consistency of concrete is maintained at a high level. Tamping is one of the usual methods adopted in compacting roof or floor slab or road pavements where the thickness of concrete is comparatively less and the surface to be finished smooth and level.

5 Curing Concrete derives its strength by the hydration of cement particles. The hydration of cement is not a momentary action but a process continuing for long time. Curing can also be described as keeping the concrete moist and warm enough so that the hydration of cement can continue. More elaborately, it can be described as the process of maintaining a satisfactory moisture content and a favorable temperature in concrete during the period immediately following placement, so that the hydration of cement may continue until the DEPARTMENT OF CIVIL ENGINEERING,AGMRCET VARUR

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desired properties are developed to a sufficient degree to meet the requirement of service. The casted cubes and cylinders are immersed in water tanks for 3 days, 7days, 14 days and 28 days. 6 Workability of Concrete Workability is the amount of useful internal work required to produce full compaction of concrete. It depends upon: 1. Types of aggregate 2. Grading of coarse and fine aggregate 3. Quantity of cement paste 4. Consistency of the cement paste

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CHAPTER 3

TESTS CONDUCTED 3.1 Slump Test Slump test is the most commonly used method of measuring consistency of concrete which can be employed either in laboratory or at site of work. It is not a suitable method for very wet or very dry concrete. It is used conveniently as a control test and gives an indication of the uniformity of concrete from batch to batch. The deformation shows the characteristics of concrete with respect for segregation The thickness of the metallic sheet for the mould should not be thinner than 1.6mm. for tamping the concrete , a steel tamping rod 16mm dia, 0.6 meteralong with bullet end is used. The mould is then filled in four layers, each approximately ¼ of the mould. Each layer is tamped 25 times by the tamping rod taking care to distribute the strokes evenly over the cross section. After the top layer has been rodded, the concrete is struck off level with a trowel and tamping rod. The mould is removed from the concrete immediately by rising itslowly and carefully in a vertical direction. This allows the concrete to subside. This subside is referred as slump of concrete. The value of slump = 90 mm

3.2 Mixing, Compaction and Curing Good concrete can be obtained only through and uniform mixing, better through and uniform mixing, better through compaction and adequate curing. In the laboratory, the concrete was mixed by hand mixing. All the constituent materials were weighed and dry mixing was carried out for about 5 minutes and then water was added. The mixing was continued till concrete of uniform consistency was obtained / the specimens were compacted using table vibrator. After 24 hours, the specimens were remolded and kept immersed curing tank containing potable water till the required curing period of 1:1.27:2.89 with water cement ratio 0.4cement replaced. The mix proportions are given in table. For control specimen the w/c ratio is 0.4. The same amount of water is used for all other specimen. The following table shows the mix proportion. Used for all other specimens. In this study the effect of Bacillus Sphaericus in concrete is studied. Bacteria added in concrete with 10ml and 20ml proportions and proper curing makes a substantial improvement in enhancing the protection of embedded in concrete.

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3.3 Strength Test 3.3.1Compressive Strength The compression test is used to determine the hardness of cubical and cylindrical specimens of concrete. The strength of a concrete specimen depends upon cement, aggregate, bond, water-cement ratio, curing temperature, and age and size of specimen. Mix design is the major factor controlling the strength of concrete. Cubes of size 15cm x 15cm x 15cm (as per IS: 10086-1982) should be cast. The specimen should be given sufficient time for hardening and then it should be cured for 3, 7, 14 and 28 days. After 3, 7, 14 and 28 days, it should be loaded in the compression testing machine and tested for maximum load. Compressive strength should be calculated by dividing maximum load by the cross- sectional area. Compressive Strength (N/mm2) =Ultimate load / C/S area of specimen 3.3.2 Split- Tensile Strength Split- tensile strength is indirect way of finding the tensile strength of concrete by subjecting the cylinder to a compressive force. Cylinders of size 150mm diameter and 300mm long were cast. After 24 hours the specimen were demoulded and subjected to water curing. After 3, 7, 14 and 28 days of curing the cylinders were taken allowed to dry and tested in compression testing machine by placing the specimen horizontal. The ultimate load of the specimen horizontal. The ultimate load of the specimen is at which the cylinder failed. Tensile stress (N/mm2) = 2P / ΠDL And the stress value is obtained in N/mm2. P is the ultimate load at which the cylinder fails. D and L are the diameter and length of the cylinder.

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CHAPTER 4

CASE STUDY The various statistics and study regarding the self-healing concrete can be understood by the following case studies.

4.1 Case Study 1 This case study portrays the advantages of cement treated with self-healing agents in the form of comparison between amounts incurred in construction of cement road with conventional cement mix vs. the cement treated with self-healing agents. For the purpose, a cement road of 2km from Kolhapur toll to Shivaji University. This cement road is a two lane road prepared using conventional methods.  Length of road = 2 km  Breadth (2 lanes) = 24 m  Depth = 0.38 m  Volume = 18,240 m3 4.1.1 Construction using Conventional Method  Amount of Cement = 10.7 bags/m3  COST of cement required = Rs.5,14,99,280  Amount of Fine aggregate = 683.24 kg/m3  COST of fine aggregate required = RS.96,32,945  Amount of Coarse aggregate = 1108 kg/m3  COST of coarse aggregate required = Rs.2,45,47,710  Amount of Plasticizers = 4.6681l/m3  COST of plasticizers required = Rs.1572  Total cost of construction = Rs.8,56,81,507 4.1.2 Construction using Cement Treated with Self-Healing Agents.  Amount of cement = 9.23 bags/m3  COST of cement required =Rs.4,59,64,800  Amount of Fine aggregate= 673.3 kg/m3  COST of fine aggregate required = Rs.94,92,816 DEPARTMENT OF CIVIL ENGINEERING,AGMRCET VARUR

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 Amount of Coarse aggregate = 1006 kg/m  COST of Coarse aggregate required = Rs.2,22,88,409  Amount of Plasticizers = 4.32l/m3  COST of Plasticizers = Rs.1568  Amount of SELF HEALING AGENT = 158.15 Kg/m3  Cost of SELF HEALING AGENT required = Rs.2,61,51,869  Total cost of construction = Rs.10,38,99,463. From the above statistics it is clear that construction cost of cement road using treated concrete is more than that by using conventional methods. Although, the cost of construction has increased by about 2 crores, but on the long run, this method is actually economic. This can be understood by analyzing the additional cost required for the repair and maintenance of roads made using conventional methods. Furthermore, the bacteria last for a century, hence improving durability manifold. This is explained elaborately in the Case Study 2.

4.2 Case Study 2 This case study basically indicates one of the many important applications of selfhealing agents. They play a major role in increasing the service life of various structures such as buildings, canals, roads etc. Self-healing agents help combat the damages occurring due to ageing by crack filling. For this case study, a bridge of cement road of span 0.5km located at the Tawade Hotel roundabout, NH4 (Pune-Bengaluru Highway), Kolhapur is considered for the calculation of its maintenance cost. This includes crack sealing, application of penetrating sealer, overlays and electrochemical treatment as a part of routine maintenance on the damages induced due regular service and ageing. Cost of maintenance is calculated as follows:  Crack sealing – Rs.99.645 / sq.ft.  Penetrating sealer – Rs.332.15 / sq.ft.  Overlays – Rs.146.146 / sq.ft.  Electrochemical treatment – Rs.3985.15 / sq.ft. Note: the above shown values are approximate.  Length of the bridge = 0.5 km = 3116 ft. DEPARTMENT OF CIVIL ENGINEERING,AGMRCET VARUR

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 Breadth of the bridge = 40 m = 131.2 ft.  Total area = 4.08,819.2 sq.ft.  Considering that 20% area of the bridge requires repairing, i.e., 8176.38 sq.ft.  Cost of crack sealing = Rs.8,14,735.38  Cost of penetrating sealer = Rs.27,15,784.617  Cost of Overlays = Rs.11,94,945.231  Cost of electrochemical treatment = Rs.3,25,89,415.4  Total

cost

of

maintenance

=

Rs.3,73,14,880.63

With

the

implementation ofself-healing agents, the above incurred maintenance cost can be reduced manifold. With self-healing agents, the following data was obtained  Area under consideration for repair = 8176.38 sq.ft.  Cost of crack sealing (Rs.9.65/sq.ft.)= Rs.78,902.07  Cost of penetrating sealer (Rs.132.15/sq.ft.)= Rs.10,80,508.617  Cost of overlays (Rs.46.146/sq.ft.)= Rs.3,77,307.23  Cost of electrochemical treatment (Rs.0/sq.ft.)= Rs.0.00  Total cost of maintenance incurred= Rs.15,44,894.28 Due to crack healing properties of self-healing agents, the above shown calculations justify its importance of applicability. It is very clear that a colossal amount of about Rs.3,57,69,986.35 can be saved on maintenance. Furthermore, by adding of self-healing agents, the service life of various structures can be improved exponentially and hence incur savings in the cost of maintenance.

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4.3 Case Study 3 Bricks are the major part of any construction. So bricks should be durable and should last longer without any damage. We visited a brick kiln in Kolhapur to collect information related to this case study. This case study focuses on comparison between conventional bricks, concrete bricks and self-healing concrete bricks. 4.3.1. Conventional Bricks  Dimensions-19*19*9  Cost of bricks-5-7 Rs.  Fuel used-coal and biomass  Gases emitted GASES

COAL

BIOMASS

SO2(mg/Nm cube)

5.2-943.2

18.3-52.4

CO (mg/Nm cube)

355-3579

2622-5026

CO2%

1.0-2.4

1.7-2.0

In a brick kiln in Kolhapur, approximately one lakh bricks are prepared out of which 20% are damaged and are of no use. In addition to this, fuel is required for burning which causes pollution. Some experts say that pollution from brick kilns is worse than that of factories. Burning of coal in brick kilns leads to formation of smoke which emits gaseous pollutants like sulfur dioxide, nitrogen oxide and particulate matter. A substance known as poly aromatic hydrocarbon is also emitted which causes vomiting, diarrhea, nausea and eye irritation and even cancer. 4.3.2. Concrete Bricks  Dimensions- 6*8*12 in.  Cost of brick-13 Rs

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4.3.3. Self-Healing Agent Bricks Bricks made with self-healing agents and concrete do not cause any type of pollution or harm to the environment. There is no fuel required for their production that’s why there is no pollution occurring. Also self-healing agent bricks last longer as compared to conventional bricks due to the ability of self-healing agents to repair the bricks.

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CONCLUSION  Self-healing concrete is a new technology developed in Delft University, Netherlands. This concrete has bacteria in the form of capsules which remain dormant till 100 years unless it receives water which is its nutrient to become active and multiplicate. Capsules receive water only when exposed to the environment which is possible when cracks appear in the structures.  The bacteria heal the cracks or gap within three to four weeks by producing limestone as its byproduct.  The cost of construction for constructing cement road has increased by about 2 crores with the implementation of self-healing agents in the cement. However, on the long run, this method is actually economic. This can be understood by analyzing the additional cost required for the repair and maintenance of roads made using conventional methods.  From our case study of analysis of maintenance cost required for a bridge, we conclude that by adding of self-healing agents, the service life of various structures can be improved exponentially and hence incur savings in the cost of maintenance.  Method of preparation of conventional bricks involves the process of baking the bricks in large kilns. This process is not environmental friendly as it involves release of poisonous gases into atmosphere, contributing towards greenhouse effect.  We can prepare bricks using self-healing concrete which are environmental friendly as they are not produced in kilns and are more durable than conventional bricks.

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REFERENCES [1] E. Schlangen, H. Jonkers, S. Qian & A. Garcia, “Recent advances on selfhealing of concrete” [2] Tae-Ho Ahn1 and Toshiharu Kishi2, “Crack Self-healing Behavior of Cementitious Composites Incorporating”, Journal of Advanced Concrete Technology Vol. 8, No. 2, 171-186, June 2010 [3] Renée M. Mors, Henk M. Jonkers, “Bacteria-based self-healing concrete [4] Asst. Prof. Mr. Samir A. Al-Mashhadi, Asst. Prof. Dr. Ghalib M. Habeeb and Abbas Kadhim Mushchil, “Control of Shrinkage Cracking in End Restrained Reinforced Concrete Walls”. International Journal of Civil Engineering and Technology (IJCIET), 5(1), 2014, pp.89–110. [5] Klaas van Breugel, “SELF-HEALING MATERIAL CONCEPTS AS SOLUTION FOR AGINGINFRASTRUCTURE, 37th Conference on Our World in Concrete & Structures,29-31 August 2012, Singapore [6] N. Ganesh Babu and Dr. S. Siddiraju, “An Experimental Study on Strength and Fracture Properties of Self-Healing Concrete”. International Journal of Civil Engineering and Technology (IJCIET), 7(3), 2016, pp.398–406. [7] J. S. Kamyotra, “Brick Kilns in India”

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