modified j-ring test for self-compacting fiber reinforced … · resistance to segregation and can...

MODIFIED J-RING TEST FORSELF-COMPACTING FIBER REINFORCED CONCRETE.

Civil Engineering DepartmentVishwakarma Institute of Information Technology, Pune .

B.E. Project

REINFORCED CONCRETE.

Guide: Prof. (Dr.) H. B. Dhonde

Presented by,TARANG S. CHOWATIA (B80390005)ADITYA R. GOYAL (B80390017)GANDHAR V. DESHPANDE (B80390067)ABHISHEK P. GOR (B80390080)NEERAJ N. TALATHI (B80390096)KHAIBER G. GANDHI (B80390109)

1. Introduction

2. Problem Statement, Research Objectives, Scope and

Significance

3. Tests for fresh properties of SCFRC.

CONTENTS

3. Tests for fresh properties of SCFRC.

4. Procedure and Methodology

5. Results & Discussions

6. Conclusions, Recommendations

7. Future Work

8. References

Background of SCFRCConventional concrete:

Laying of concrete drawbacks

Development of SCC:Benefits over conventional concreteBenefits over conventional concreteDrawbacks

Development of SCFRC:BenefitsTypes of fibres: Steel, Glass, Polypropylene, Natural fibres, etc.Limitations

A Self Compacting Concrete (SCC) is defined as a concrete that has excellent deformability and high

resistance to segregation and can be filled in heavily reinforced or restricted area under its own weight without

applying vibration [ACI 237-2007]

Such a concrete when reinforced with fibers is called as self compacting fiber reinforced concrete.

Advantages:• Improved structural strength.

• Reduction in steel reinforcement requirements.

• Improved ductility and durability

• Reduction in crack widths and

• Improved and more uniform architectural surface finish with little to no remedial surface work.

• Elimination of vibrator noise• Reduction in crack widths and

control the crack widths tightly, thus improving durability.

• Improved impact and abrasion-resistance.

• Improved freeze-thaw resistance.

• Increased toughness.

Disadvantages:• Heat of Hydration is higher than conventional concrete

• Shrinkage issue may occur if cement content is high.

• Formwork Pressure is larger

• Quality Assurance & Quality Control.

• Cost of SCFRC is 2 – 3 times higher than that of the normal • Cost of SCFRC is 2 – 3 times higher than that of the normal fiber reinforced concrete

• Injury to personnel being scraped or cut by an exposed fiber while working on the concrete surface is also possible.

• Requires number of batch trials.

Properties of SCFRC:

• Fresh Properties:

Workability:a) Filing Ability (unconfined flowability)b) Passing ability (confined flowability)c) Stability c) Stability

- Dynamic- Static

• Harden Properties:a) Strengthb) Durabilityc) Toughnessd) Appearance

2. Problem Statement:The J-Ring Passing Ability Test (Standard and ASTM ) havecertain disadvantages such as;

Not realistic and rational solutions

Cumbersome, time consuming and large numbers ofcalculations.calculations.

Less reliable results , not good correlation between each other.

Hence, to improve on the drawbacks of the variousconventional tests and to provide a rationale approach formeasuring the passing ability, a new Modified J-Ring Test(MJ-Ring) is proposed which is easy to perform and evaluate.

(Other methods)

Observe the passing ability of self compacting fiber reinforced

concrete (SCFRC) with respect to Modified J-ring test.

Produce different SCC/SCFRC mixes, co-relation between

Research objective

conventional and proposed methods.

A procedure to determine the precise passing ability of SCC/SCFRC.

Applicable for laboratory and site use.

The Modified J-Ring test measures three parameters: flow spread, flow

time and stability.

Research significance

The J-Ring flow spread indicates the restricted deformability of

SCC/SCFRC due to blocking effect of reinforcement bars and the flow

time indicates the rate of deformation within a defined flow distance.

The MJ-Ring test measures the passing ability directly on basis of

weight.

It provides a single MJ-Ring value of the mix.

Research Scope :

The project is limited to testing of SCC and SCFRC mixes.

The material used should be locally available.

Obtaining good range of Passing Ability Value. Obtaining good range of Passing Ability Value.

Comparison of Standard J-Ring, ASTM J-Ring and MJ-Ring test.

Constituents of SCFRC:

• Cement (OPC 53 grade)

• Aggregates:

Fine: Well graded river-bed sand Fine: Well graded river-bed sand

Coarse: Well graded10-20mm Basalt

Course: Well graded 20mm rounded (pebbles)

• Water

• Fibers ( Steel Fiber )

• Admixtures (H.R.W.R.A)

Target: Slump Flow > 635 mm.T50 = 3 – 7 sec.

Slump Flow & T50:

Visual Stability Index(VSI)Target: 0 – 1 max

Vsi 0 - No segregation & No bleeding

Vsi 1 - No segregation, slight bleeding

Vsi 2 - Slight segregation, clear bleeding

ClearBleeding

Vsi 3 - Clear segregation & bleeding

Segregation

ClearBleeding

Standard J-ring Test:

To determine the passing ability of the SCC.Origin - Japan. It was published in EFNARC, PCI codes.J-Ring test value = 2(ham – hbm) – (h1m – ham)

Advantages:

Widely used method.

Considers the flow in all the directions.

It represents field conditions well and accurately distinguishes between mixtures

Disadvantages:

Relationships not wellestablished

Cumbersome recordingtechnique

Skilled and experiencedistinguishes between mixtures with varying degree of passing ability.

Low cost and portable.

Skilled and experienceoperator

More number of calculations

Dimension mm.A 300 +/- 3.3B 38 +/- 1.5

J-Ring Apparatus (ASTM C1621, 2009)

B 38 +/- 1.5C 16 +/- 3.3D 58.9 +/- 1.5E 25 +/- 1.5F 200 +/-1.5

Slump flow(d4)= (d1+d2)/2

J-Ring flow(d3) =(d1+d2)/2

ASTM J-Ring Value = Difference between the average values of the restricted slump flow and unrestricted slump flow.

J-Ring flow(d3) =(d1+d2)/2

Passing ability of concrete= d4-d3

Advantages of ASTM J-Ring:• It is a simple technique• Can be used in laboratory and on site.• The measurements and the calculations are quite easy as only the flowof SCC is to be measured.• The equipment is low in cost and portable.

Disadvantages of ASTM J-Ring:Disadvantages of ASTM J-Ring:• Less rational technique.• Indirect representation of the passing ability.• The readings include even the mortar halo if formed when the SCC

flows out through the J-Ring.• No relation with Standard J-Ring value.• No “precision and bias” study performed by ASTM.

Visual Blocking Index (VBI)

• The J-Ring is easy to use and provides a measure of “flow loss” due to presence of obstacles.

• Rate the concrete patty after testing of J-Ring according to Visual Blocking index (VBI):

No evidence of blocking resulting in a pile of coarse aggregate in the middle of the patty and no

0coarse aggregate in the middle of the patty and no evidence of bleed streaking behind the rebar obstacles.

1A slight pile of coarse aggregate in the middle of the patty and slight evidence of bleed streaking behind the rebar obstacles.

2A clear pile of coarse aggregate in the middle of the patty and significant bleed streaking.

3Significant blocking of aggregate behind the rebar obstacles, will usually result in a significant decrease in flow value.

Modified J-Ring Test:

The MJ-Ring value is the ratio of the weight of concrete that has

Procedure and Methodology:

The MJ-Ring value is the ratio of the weight of concrete that has

passed through the reinforcing bars to the total weight of concrete.

The MJ-Ring apparatus is just a simple modification to the Standard

J-Ring apparatus wherein a base plate is attached at the bottom to hold the

concrete which is blocked within the ring.

DRAWING

Modified J-Ring Apparatus:

MJ-Ring Test:

• Apparatus

Slump Cone Mold

Modified J-Ring

Non absorbent Plywood or Metal Tray and/or plastic sheet

Weighing Balance.

MJ-Ring + Retained SCC

Plywood + Passed SCC

MJ-Ring value (%) = Weight of concrete passing the barsTotal Weight of concrete

= [W / (W +W -W )] x 100

CALCULATIONS

= [W4/ (W4+W1-W0)] x 100

Empty weight of MJ-Ring (W0) MJ ring + SCC weight (W1) Empty weight of plywood/tray (W3) Weight of passed SCC (including plywood) (W2) Weight of passed SCC (W4) = W2-W3

Sr.No

Points Japanese J ring ASTM J ring Modified J ring

Comparison between traditional J-Ring,ASTM J-Ring and modified J-Ring.

1Measurement Techniques

Vertical distances are measured with respect to the ring at different points inside and outside

the J-ring.

The Slump flow is measured in terms of its diameter and is compared with the flow when the J-ring is placed.

The weight of the concrete that has

flown out of J-Ring is measured.

Sr.No Points

StandardJ ring ASTM J ring Modified J ring

2 Apparatus

J ring Modified J ring

Sr.No Points Standard J ring ASTM J ring Modified J ring

It is the relativeweighted difference

between the height of

Slump flow (d4)= (d1+d2)/2

Weight of concrete Passed

Total weight of concrete sample

3 Formula

between the height of concrete inside and

outside the J-ring. The height considered is the average of four

different points inside and outside the J-ring

J-Ring flow (d3) = (d1+d2)/2

Passing ability of concrete = d4-d3

Empty weight of J-ring (w0) J ring + SCC weight (W1)

Empty weight of bucket (W3)Weight of passed SCC(including bucket) (W2)

Weight of passed SCC (W4)

J-Ring value= W4W4+W1-W0

Sr.No Points

Standard J ring ASTM J ring Modified J-Ring

Lab

ou

r

Skilled

1 no.

(Measuring reading

and calculating,

helper)

1 no.

(Measuring reading and

calculating, helper)

Semi-skilled

1 no.

(Holding the slump 1 no.

(Holding the slump

1 no.


4

Lab

ou

r

Semi-skilled(Holding the slump

cone, writing

readings)

(Holding the slump

cone, writing readings)


calculating, helper)

Un-skilled 0 0

1 no.

(Holding the slump

cone, writing readings)

Total 2 Nos 2 Nos 2 Nos

Time Mins 7.5 3.5 7

Workability Tests performed on SCFRC :

TEST NAME CATEGORY CHARACTERISTICWHAT TEST MEASURES

Slump Flow Free Flow Filing Ability Flow Distance

Visual stability Index (VSI)

Static Condition resistance to SegregationVisual stability of the

mixture

T50 Free Flow Filing Ability rate of flow

Visual Blocking Index (VBI)

Static Condition BlockingIntensity of blocking of concrete inside J-Ring

Passing Ability Test

Confined Flow Passing ability flow rate and distance

Standard J-Ring Confined Flow Passing ability flow rate and distance

ASTM J-Ring Confined Flow Passing ability flow rate and distance

MJ-Ring Confined Flow Passing Ability Flow rate and passing %

Mix Proportions

Sr No. Mix cement FA CAAmount of

fibres Vf aspect ratio Vf.Lf/Df Water HRWR CA/FA W/C

Name kg/m3 kg/m3 kg/m3 kg/batch mix % % kg/m3 kg/m3

1 SCFRC 1-S 480 800 900 0.14 0.1274 63.64 8.11 170 8.65 1.13 0.35

2 SCFRC 2-S 480 800 900 0.19 0.1729 63.64 11.00 170 8.65 1.13 0.35

3 SCFRC 3-S 500 900 750 0.27 0.2457 63.64 15.63 170 6.40 0.83 0.34

4 SCFRC 4-S 500 900 750 0.37 0.3367 63.64 21.42 170 6.40 0.83 0.34

5 SCFRC 9-S 450 1000 800 0.84 0.7643 63.64 48.64 160 7.50 0.80 0.36

6 SCFRC 10-S 450 1000 800 0.56 0.5096 63.64 32.43 160 7.50 0.80 0.36

7 SCFRC 15-S 450 950 750 0.68 0.6187 63.64 39.37 160 7.50 0.79 0.36

8 SCFRC 19-S 480 800 900 0.96 0.8735 63.64 55.59 175 8.70 1.13 0.368 SCFRC 19-S 480 800 900 0.96 0.8735 63.64 55.59 175 8.70 1.13 0.36

9 SCFRC 5-L 500 900 750 0.3 0.2730 80.00 21.84 170 6.40 0.83 0.34

10 SCFRC 6-L 500 900 750 0.57 0.5187 80.00 41.49 170 6.40 0.83 0.34

11 SCFRC 7-L 450 1000 800 0.64 0.5823 80.00 46.59 160 7.50 0.80 0.36

12 SCFRC 8-L 450 1000 800 0.7 0.6369 80.00 50.96 160 7.50 0.80 0.36

13 SCFRC 11-L 480 800 900 0.97 0.6272 80.00 50.18 170 8.65 1.13 0.35

14 SCFRC 12-L 480 800 900 1.04 0.6725 80.00 53.80 170 8.65 1.13 0.35

15 SCFRC 17-L 500 900 750 0.4 0.3640 80.00 29.12 165 6.50 0.83 0.33

16 SCFRC 18-L 500 900 750 0.8 0.7279 80.00 58.23 165 6.50 0.83 0.33

17 SCFRC 16-L 450 950 750 0.43 0.3913 80.00 31.30 160 7.50 0.79 0.36

18SCFRC 13-

PL 450 900 950 0.14 0.1274 80.00 10.19 150 6.75 1.06 0.33

19SCFRC 14-

PS 450 900 950 0.15 0.1365 63.64 8.69 150 6.75 1.06 0.33

Results

700

720

740Variation of Slump Flow (Flowability) with Fiber Factor SMALL FIBERS

Correlation between Fiber Factor (%) and Slump Flow (mm):

Short Fibers

580

600

620

640

660

680

700

5.000 10.000 15.000 20.000 25.000 30.000 35.000 40.000 45.000 50.000

Slu

mp

Flo

w (

mm

)

Fiber Factor (%) of SCFRC Mixes

670

680

690

700

Slu

mp

Flo

w (

mm

)

Correlation between Fiber Factor (%) and Slump Flow (mm):

Long Fibers

600

610

620

630

640

650

660

670

20.000 30.000 40.000 50.000 60.000 70.000 80.000

Slu

mp

Flo

w (

mm

)


4.5

5

5.5

Tim

e (

se

c)

Correlation between Fiber Factor (%) and T50 Time (sec):

Short Fibers

3

3.5

4

4.5

5.000 10.000 15.000 20.000 25.000 30.000 35.000 40.000 45.000 50.000

T5

0T

ime

(s

ec

)


4.4

4.6

4.8

5

Correlation between Fiber Factor (%) and T50 Time (sec):

Long Fibers

3

3.2

3.4

3.6

3.8

4

4.2

20.000 30.000 40.000 50.000 60.000 70.000 80.000

T5

0T

ime

(s

ec

)


Correlation between Fiber Factor (%) and Standard J-Ring Value (mm):

Short Fibers


Long Fibers

Correlation between Fiber Factor (%) and ASTM J-Ring Value (mm):

Short Fibers


Long Fibers

Correlation between Fiber Factor (%) and MJ-Ring Value (%):

Short Fibers

Correlation between Fiber Factor (%) and J-Ring Value (%):

Long Fibers

Correlation between Standard J-Ring Value (mm) and ASTM J-Ring Value (mm):

Correlation between ASTM J-Ring Value (mm) and MJ-Ring Value (mm):

Correlation between STANDARD J-Ring Value (mm) and MJ-Ring Value (mm):

A substitute to the conventionally used methods for measuringthe passing ability of SCC.A simple, easy to perform test, yet much more accurate andsensitive than the Standard J-Ring.It measures directly and accurately the weight of concrete that

CONCLUSIONS:

It measures directly and accurately the weight of concrete thathas passed through the bars and express it as the percentage ofthe total concrete sampled.It gives a single value of passing ability of SCC mixes.Even an unskilled labour can conduct the MJ-Ring test.MJ-Ring Value clearly indicates quantitatively the relativeamount of SCC that passes through the J-Ring (eg. 50% byweight), thus providing a better indication of passing ability.

RECOMMENDATIONS:

We recommend the following guidelines for passing abilityof various MJ-Ring values on the basis of our limited studies

Table: Recommendations of Modified J-Ring values

PerformancePassing Ability (%

by weight)Recommendation

Good > 50 Acceptable

Medium 45 – 50 Acceptable

Fair 35 – 45 Unacceptable

Poor < 35 Unacceptable

Table: Recommendations of Modified J-Ring values

In this study limited SCC mixes were tested. Therefore, toestablish the MJ-Ring Test as a standard test more SCC mixesneeds to be tested.Fabrication of lighter Modified J-Ring Apparatus usingaluminum can be done.Testing of Self Compacting Fibre Reinforced Concrete

FUTURE WORK:

Testing of Self Compacting Fibre Reinforced Concrete(SCFRC) through Modified J-Ring Test can be performed infuture.An adjustable MJ-Ring apparatus can also be fabricated outof aluminum that has a capacity of changing the rebar spacingdepending on the aggregate size and fibres used.

MAJOR References1. Hemant B. Dhonde, Y. L. Mo, Thomas T. C. Hsu, and John Vogel “Fresh and

Hardened Properties of Self-Consolidating Fiber-Reinforced Concrete” ACI Materials Journal/September-October 2007.

2.

3. “Standard Test Method for Passing Ability of Self Consolidating Concrete by J-Ring” ASTM C 1621/C 1621M – 06

4. “Self Consolidating Concrete” ACI 237R- 07

5. “Standard Test Method for Slump Flow of Self Consolidating Concrete by J-Ring” ASTM C 1611/C 1611M – 05

modified j-ring test for self-compacting fiber reinforced … · resistance to segregation and can...

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