New Construction Materials - InDIA 2010

8/10/2019 New Construction Materials - InDIA 2010

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DEVELOPMENT OF NEW CONSTRUCTIONMATERIALS BACTERIAL CONCRETE,BASALT REINFORCEMENT BARS AND

SYNTHETIC STRUCTURAL FIBER REINFORCEDCONCRETE

V. RamakrishnanRegents Distinguished Professor Emeritus


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Outline of Presentation

Basalt 3D reinforced concrete andbasalt reinforcing rodsBacterial concrete biosealantsConstruction of highway structureswith synthetic FRC


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Concrete is a DesignMaterial


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Reinforced Basalt Fiber Concrete Composites

Dr. V. RamakrishnanRegents Distinguished ProfessorCivil Engineering Department

South Dakota Tech, USA
http://www.sdsmt.edu/


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Chopped Basalt Fiber Strands


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Basalt Fabrics


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Basalt Geo-Mesh


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Basalt Rebars and RebarReinforced Concrete


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Concrete Reinforced With BasaltFiber Composite Rebars


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Properties of Basalt Rebar

This rebar consists of 80% fibersIt is made, by utilizing a resin (epoxy) binder.Tensile strength is three times that of the steel bar.Basalt rebar has one-third of the weight of steel.1 Kg of Basalt can replace 9 Kg of steel.The thermal expansion coefficient is very close to that

of concrete.High mechanical performance/price ratio.High corrosion resistance.High Resistance to alkaline attack.

Potential for replacement of steel in reinforced


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Comparison Chart

Properties Basalt Wires Metal HotRolled Steel

Tensile Strength (Mpa) 1080-1380 390-450

Compressive Strength (Mpa) 460-480 180

Modulus of Elasticity (Mpa) 100,000-110,000 200,000

Fracture Elongation 2.0 % 38 %

Water absorption (24 hrs) % 0.01

Density g/cm 3 1.8 7.8

Melting Temperature 1350 C 1500 C


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Failed Specimens Basalt Cables


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Stress Vs. Strain Graph

0

200

400

600

800

1000

1200

1400

1600

0 0.005 0.01 0.015 0.02 0.025 0.03

Strain (mm/mm)

S t r e s s

( M P a )

Modulus of Elasticity = 62100 MPaDia. Of Rod = 14.2 mm


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Test Set-Up


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PHASE II Modified Rebars


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PHASE II Modified Rebars


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Principle of Smart Memory Alloy

Anchors


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PHASE II - Research Tasks

To study the bond between the modified basaltrebars and cables, and concrete by conducting bondtests according to the procedure of ASTM C 234.To determine the cracking and ultimate moment oftwo extremely under-reinforced beams, and todetermine the mode of failure of the modified basaltrebar reinforced concrete beams.To determine the cracking and ultimate moment offive lightly under-reinforced beams, and to determinethe mode of failure of the modified basalt rebar

reinforced concrete beams


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Task 1: Bond Test on Basalt Rebars(ASTM C 234)


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Bond Stress Vs. Slip

0

2

4

6

8

10

12

0 1 2 3 4 5

Slip (mm)

B

o n

d S t r e s s (

M P a

)4 - Slot Basalt Bar

8 - Slot Basalt Bar

Plain Basalt Bar


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Failure Pattern


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Findings

There was no slip of the rebars in any of thespecimens tested and there was no evidence of bondfailure between the concrete and the modified basaltrebars.


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Failed Specimens


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Corrugated Basalt Rebar Beam

(Failure Pattern)


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Manually Twisted Basalt Strand

Rebar Beam (Failure Pattern)


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Manufacturer Supplied Basalt Strand

Rebar Beam


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Manufacturer Supplied Basalt Strand

Rebar Beam (Failure Pattern)


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Fe-Mn-Ni Smart Alloy Anchor Basalt

Rebar Beam


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Fe-Mn-Ni Smart Alloy Anchor BasaltRebar Beam (Failure Pattern)


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Fe-Mn-Ni Smart Alloy Anchor BasaltRebar Beam (Failure Pattern)


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Ti-Ni Smart Alloy Anchor BasaltRebar Beam (Failure Pattern)


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Ti-Ni Smart Alloy Anchor BasaltRebar Beam (Failure Pattern)


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Load Vs. Compressive Micro Strain

020406080

100120140

160180200

0 500 1000 1500 2000 2500 3000

Compressive Micro Strain

L o a

d ( K N )

Strain gauge located at 6.35 mm from thetop (compression side) at the center of the beam

First crack ofconcrete


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Load Vs. Deflection Graph (Cable as Rebar)

0

510

15

20

2530

35

40

45

0 5 10 15 20 25Deflection (mm)

L o a

d ( K N )

Average deflection at the center of the beam

First crack of concrete


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Load Vs. Deflection Graph (Plain Rebar)

0

10

20

30

40

50

60

70

80

0 0.5 1 1.5 2 2.5 3

Deflection (mm)

L o a

d ( K N )

(Beam Size = (304.8mm x 304.8mm x 1295.4mm)(Diameter of Bar = 14.2mm)


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Basalt Rod Impressions on

Concrete


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Comparison of the Calculated and ActualMoments (Modified Basalt Rebars)

Beam Type of FailureNo. Ultimate Cracking Ultimate Cracking

N-m N-m N-m N-m

BRC-3 8407 3107 8619 3260

BRC-4 12577 2551 12983 3376

BRC-5 1137 481 765 505

BRC-6 33184 6475 29685 6199

BRC-7 38724 6610 32047 6160

Actual Moments Calculated Moments

Primary flexural failure and

secondar shear failure.

Beam failed primarily inflexure by splitting into two

pieces after fracture of rebar Primary flexural failure andsecondary shear failure.

Primary flexural failure andsecondary shear failure.Typical flexural failure with

partial fracture of strands


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The bond between all the modified basalt rebars andconcrete was extremely good.The ultimate moment was much higher than the first

crack moment in all the beams tested, indicating agood bond between rebar and concrete.The deflections were considerable indicatingadequate ductility.

All the beams had primary flexural failure and a fewbeams had secondary shear failure.There was no slip of the rebars in any of the beamstested and there was no evidence of bond failure.

Conclusions: 2-DimensionallyReinforced Basalt Fiber Concrete


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RAEM 2006

Bacterial Concrete

Concrete External RemediationBacteria can act as a sealant in remediatingalready existing cracks by precipitating calcite.It also increases the strength characteristics ofalready cracked concrete.

Concrete Internal RemediationWhen mixed in concrete bacteria can act as a self-

remediating biomaterial in reducing the microcracks.It also increases the durability performance.It also reduces the plastic shrinkage cracks in

concrete.


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RAEM 2006

Principle of Bacterial MineralPrecipitation

Microorganisms (cell surface charge is negative)draw cations including Ca 2+ from the environmentto deposit on the cell surface.

Ca 2+ + Cell Cell - Ca 2+

Cell - Ca 2+ + CO 32- Cell - CaCO 3


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RAEM 2006

Concrete micro cracks


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RAEM 2006

Plastic shrinkage micro crack inconcrete


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RAEM 2006

Close-up view of micro crack


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RAEM 2006

Partially remediated micro crack


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RAEM 2006

Cluster of Calcite Crystals


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RAEM 2006



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RAEM 2006



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RAEM 2006

Full Grown Calcite Crystals


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RAEM 2006

External Remediated Slabs

0

1020

30

40

50

6070

80

90

100

Slabs

P e r c e n

t a g e r e

d u c t

i o n

i n p l a s

t i c

s h r i n k a g e c r a c k

a r e a

C11 - Slab remediated with Bacteriaand medium (Placed at the Bottom)C12 - Slab remediated with Bacteriaand medium (Placed at the Top)

C21 - Slab remediated with onlymediumC22 - Slab Remediated with onlywater

Comparison of Modulus of Rupture of Cracked


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RAEM 2006

p pSpecimens Remediated with Different Concentrationsof Bacteria and Uncracked Specimens (Control)

0

1

2

3

4

5

Control 10^9Cells/ml

8.6 x10^8

Cells/ml

10^8Cells/ml

10^7Cells/ml

NoCells/ml

Specimens

o

u u s o

u p t u r e

a


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RAEM 2006

Durability Characteristicsof Bacterial Concrete

Objectives


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RAEM 2006

Alkali Aggregate Reactivity (ASTM C 1260)

Specimens were cured inUrea - CaCl 2 for 7 days.Oven at 80 2.0 0C (176 3.6 0F) for 24 hrs.Initial reading1N NaOH (40 gms ofSodium hydroxide in 1000

ml of water) and were placed in the oven.The length comparatorreadings were taken on 3,

7,11 and 14th day.

Eff f Diff C i f


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RAEM 2006

Effect of Different Concentrations ofBacteria on AAR of Concrete Beams

0.00

0.01

0.02

0.03

0.04

0.05

0 2 4 6 8 10 12 14 16Age (Days)

M

e a n e x p a n s i o n

( % ) Zero cells/ml (Control)

10^7 Cells/ml10^8 Cells/ml

10^9 Cells/ml

Eff t f B t i S d d i Diff t


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RAEM 2006

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0 2 4 6 8 10 12 14 16Age (Days)

M e a n e x p a n s

i o n ( % )

Control (Without Bacteria)Bacteria in Water Bacteria in Phosphate-Buffer Bacteria in Urea-Calcium Chloride

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0 2 4 6 8 10 12 14 16Age (Days)

M e a n e x p a n s

i o n ( % )

Control (Without Bacteria)Bacteria in Water Bacteria in Phosphate-Buffer Bacteria in Urea-Calcium Chloride

Effect of Bacteria Suspended in DifferentMediums on AAR of Concrete Beams


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ff f ff f


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RAEM 2006

Effect of Different Concentrations of Bacteriaon Sulfate Attack Resistance of Concrete Beams

0.000

0.005

0.010

0.015

0.020

0 1 2 3 4 5 6 7 8 9Immersion Age (Weeks)

M e a n e x p a m s i o n

( % )

Zero Cells/ml (Control)10^8 Cells/ml8.6 X 10^8 Cells/ml10^9 Cells/ml

Effect of Bacteria Suspended in Different


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RAEM 2006

pMediums on Sulfate Attack Resistance ofConcrete Beams

0.000

0.005

0.010

0.015

0.020

0 1 2 3 4 5 6 7 8 9

Immersion Age (Weeks)

M e a n e x p a n s i o n

( %Control (Without Bacteria)Bacteria in Phosphate-Buffer Bacteria in Water Bacteria in Urea-Calcium Chloride


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RAEM 2006

Freeze Thaw Durability (ASTM C 666)

Specimens were cured inUrea - CaCl 2 for 7 daysPulse time, weight change

and length comparatorreadings were recorded forevery 30 cycles until thecompletion of 210 cycles

of freezing and thawingPulse time was used tocalculate the pulsevelocity, and the durability

factor


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Effect of Different Concentrations of Bacteria


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RAEM 2006

0204060

80100

Zero Cells/ml(Control)

1 x 10^6Cells/ml

1 x 10^7Cells/ml

1 x 10^8Cells/ml

Mix Designation

D u r a b

i l i t y F a c t o r

( % ) 0 cycles 180 cycles

Effect of Different Concentrations of Bacteriaon Freeze Thaw Durability of Concrete Beams


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RAEM 2006

Durability Characteristics ofBacterial Concrete

Scanning Electron Microscopy Investigation


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RAEM 2006

Bacteria acting as nucleation sites

Scanning Electron Microscopy


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RAEM 2006

Scanning Electron MicroscopyInvestigation

SURFACE I

SURFACE II



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RAEM 2006


Element Element % Compound Compound %

Na 0.3 Na 2O 0.4

Mg 0.05 MgO 0

Al 7.1 Al 2O3 13.5Si 25.9 SiO 2 55.4

S 0 SO 3 0

Cl 0.2

K 15.2 K 2O 18.4

Ca 8.4 CaO 11.7

Fe 0.3 Fe 2O 3 0.4

O 42.5

SURFACE I

SURFACE II



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RAEM 2006


Element Element % Compound Compound %

Na 0.5 Na 2O 0.7

Mg 0.6 MgO 1.0

Al 0.2 Al 2O3 0.4

Si 1.0 SiO 2 2.2

S 0 SO 3 0

Cl 0 0

K 0 K 2O 0

Ca 68.8 CaO 96.3

Fe 0 Fe 2O3 0

O 29.2

SURFACE I

SURFACE II



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RAEM 2006


SURFACE I

SURFACE II


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RAEM 2006

Bacterial Impressions in Calcite Crystals


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RAEM 2006

Findings

The presence of bacteria increased theresistance of concrete towards alkali, sulfate,freeze-thaw attack and drying shrinkage.

Phosphate-buffer proved to be an effectivemedium for bacteria than the other twomediums.Bacteria in water did not perform well asexpected.Durability of concrete increased with theincrease in the concentration of bacteria .


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