Elongation and Flakiness Test

ELONGATION AND FLAKINESS TEST 1.0 ELONGATION TEST INTRODUCTION The type of rocks and type of crushing machine highly determine the shape and size of the aggregates produced. Elongated and flaky stones are normally not very suitable for roadwork’s since the shape and the make them difficult to compact. As such the flakiness and elongation test mush be carried out to determine the suitability of the material. Aggregates which are flaky and/or elongated will often lower the workability of a concrete mix and may also affect long term durability. In bituminous mixtures flaky aggregate makes for a harsh mix and may also crack and break up during compaction by rolling. PURPOSE i.

To obtain detail of aggregates

ii.

To determine the suitability of aggregates

iii.

To determine the elongation of aggregates

iv.

To determine the suitable aggregates for highway construction

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OBJECTIVE i.

This test is to determine elongation index of the given aggregates sample.

ii.

This test is to determine the suitability of the material.

THEORY This method is based on the classification of aggregate particles as elongated when they have a length (greatest dimension) of more than 1.8 of their nominal size, this size being taken as the mean of the limiting sieve apertures used for determining the sizefraction in which the particle occurs. The Elongation Index of an aggregate sample is found by separating the elongated particles and expressing their mass as a percentage of the mass of the sample tested. The test is not applicable to material passing a 6.30 mm BS test sieve or retained on a 50.0 mm BS test sieve. The particle shape of aggregate is determined by the percentages of flaky and elongated particles contained in it. In case of gravel it is determined by its Angularity Number. Flakiness and Elongation tests are conducted on coarse aggregates to assess the shape of aggregates. Aggregates which are flaky or elongated are detrimental to the higher workability and stability of mixes. They are not conducive to good interlocking and hence the mixes with an excess of such particles are difficult to compact to the required degree. For base coarse and construction of bituminous and cement concrete types, the presence of flaky and elongated particles are considered undesirable as they may cause inherent weakness with probabilities of breaking down under heavy loads. Rounded aggregates are preferred in cement concrete road construction as the workability of concrete improves. Angular shape of particles are desirable for granular base coarse due to increased stability derived from the better interlocking when the shape of aggregates deviates more from the spherical shape, as in the case of angular, flaky and elongated aggregates, the void content in an aggregate of any specified size increases and hence the grain size distribution of the graded aggregates has to be suitably altered in order to obtain minimum voids in the dry mix or the highest dry density. 2

APPARATUS  Sieve

>Riffle box

 Sieve Shaker

>Length Gauge

 Balance machine

3

PROCEDURE 1. First, we were dividing the aggregate sample using a riffle divider. 2. After that, we weights 4 kilograms of the aggregates. 3. Then, we sift aggregates by sieve 25mm, 19mm, 12.5mm, and 6.25mm (start with the largest size) in order to separate the aggregate sample to a particular group using sieve shaker. 4. After we finish sift the aggregate about 5 minutes then, we had to record and indicate the weights of the aggregates are stuck on each sieve, including the retention of the tray. 5. Next step, select the length of aggregates (according to specifications above) from each sieve separately. Record the weights and mass of aggregate length of each side of the sieve. 6. Finally we record our findings in the table provided on the side.

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RESULT Sieve size (mm)

Mass retained (g)

Cumulative mass retained (g)

Size of elongated aggregates (mm)

25 19 12.5 6.30 PAN

1189 2067 3315 1695 889

137 1070 3263 3931 4002

20-28 20-28 20-28 20-14 14-10

23 18 13 3 0

Mass retained (g)

Mass of aggregates (g)

1189 2067 3315 1695 889

137 1070 3263 3931 4002

Size of elongated aggregates (mm) 20-28 20-28 20-28 20-14 14-10

Sieve size (mm) 25 19 12.5 6.30 PAN

Mass of sieve (g)

1052 1134 1122 1027 818

CALCULATION Elongation index = Total mass of elongated aggregates

x 100

Total mass of aggregates = 57 4002 = 1.42%

x 100

5

Mass of elongated aggregates retain (g)

Cumulative mass of elongated aggregates (g) 23 41 54 57 57

Mass of one aggregate (g) 23 18 13 3 0

DISCUSSION Based on the result obtained, each sample collected has about less than 5% elongated aggregates. This shows that the samples are quite suitable to be used for bituminous mix. But, the appropriate percentage of elongated aggregates in each sample is determined by the specification stated in respective manual used for different purpose. Aggregates that elongated could always lower the workability of concrete and also affects its long-term durability. In bituminous mixtures, flaky aggregates make for a harsh mix that can crack or break up during the compaction process. The total mass retained were 4002 gram, this because it was calibration error while doing the elongation test. This affected by the cleanliness of the sieve, maybe we did not clean it properly. CONCLUSION After carried out the test, the elongation index of the collected sample is determined. By knowing the elongation index is 1.42%, the sample collected is very suitable for bituminous mix. But, different bituminous mix may require different proportion of elongated aggregates. Therefore, appropriate manual should be referred in order to gain the right mixture of aggregates for an accurate bituminous mix.

6

REFERENCES  INTERNET o http://www.scribd.com/doc/48738827/Flakiness-Index 

TIME= 20.01 pm



DATE= 23/8/2012

o http://www.scribd.com/doc/60508812/Elongation-Index-Test 

TIME= 20.20 pm



DATE= 23/8/2012

o http://www.ele.com/euro/pdfs/aggregatespdf.pdf 

TIME= 20.40 pm



DATE= 23/8/2012

 BOOK o Highway Materials (A Guide Book for Beginners), Ratnasamy Muniandy, Radin Umar Radin Sohadi, Penerbit UPM, 2001. 

TIME=2100 pm



DATE= 26/8/2012

o Highway Engineering, Paul H. Wright, 6th edition, John Wiley & Son, Inc. 1996 

TIME=1000 am



DATE= 26/8/2012

7

APPENDIX

8

2.0 FLAKINESS TEST INTRODUCTION The type of rocks and type of crushing machine highly determine the shape and size of the aggregates produced. Elongated and flaky stones are normally not very suitable for roadwork’s since the shape and the make them difficult to compact. As such the flakiness and elongation test mush be carried out to determine the suitability of the material. Aggregates which are flaky and/or elongated will often lower the workability of a concrete mix and may also affect long term durability. In bituminous mixtures flaky aggregate makes for a harsh mix and may also crack and break up during compaction by rolling. PURPOSE v.

To obtain detail of aggregates

vi.

To determine the suitability of aggregates

vii.

To determine the elongation of aggregates

viii.

To determine the suitable aggregates for highway construction

OBJECTIVE This test is to determine the suitability of the material.

9

THEORY The particle shape of aggregate is determined by the percentages of flaky and elongated particles contained in it. In case of gravel it is determined by its Angularity Number. Flakiness and Elongation tests are conducted on coarse aggregates to assess the shape of aggregates. Aggregates which are flaky or elongated are detrimental to the higher workability and stability of mixes. They are not conducive to good interlocking and hence the mixes with an excess of such particles are difficult to compact to the required degree. For base coarse and construction of bituminous and cement concrete types, the presence of flaky and elongated particles are considered undesirable as they may cause inherent weakness with probabilities of breaking down under heavy loads. Rounded aggregates are preferred in cement concrete road construction as the workability of concrete improves. Angular shape of particles are desirable for granular base coarse due to increased stability derived from the better interlocking when the shape of aggregates deviates more from the spherical shape, as in the case of angular, flaky and elongated aggregates, the void content in an aggregate of any specified size increases and hence the grain size distribution of the graded aggregates has to be suitably altered in order to obtain minimum voids in the dry mix or the highest dry density.

APPARATUS  Sieve (50mm, 37.5mm, 25mm, 20mm and pan)  Sieve Shaker  Balance machine  A metal gauge plate.

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PROCEDURES 1. Three samples of aggregates weighing 2.5kg each is prepared: The aggregates of the first sample passing 50mm BS sieve and retained on 37.5 mm BS sieve, those of the second sample passing 37.5 mm BS sieve and retained on the 20 mm BS sieve. 2. Each sample is gauged in turn of thickness on the metal gauge. 3. Finally, weighed the passing material of each sample.

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RESULT Passing

Retained

Sample (Nos)

Passing (Nos)

Flakiness

sieve (mm)

sieve (mm)

50

37.5

0

0

0

37.5

25

95

11

11.58

25

20

146

12

8.22

Average

6.6 %

index (%)

Example calculation The flakiness index of aggregate passing sieve size 37.5mm and retained on sieve size 25mm was calculated as follows: Flakiness index (%)

Average

Number of aggreate pas sin g x 100 Total number aggregate

=

=

11 x 100 95

=

11.58%

=

Summation of all frations No of fraction

=

(0  11.58  8.22) 3

=

6.6%

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DISCUSSION Based on the result obtained, each sample collected has about less than 15% flaky aggregates. This shows that the samples are quite suitable to be used for bituminous mix. But, the appropriate percentage of flaky aggregates in each sample is determined by the specification stated in respective manual used for different purpose. For sample passed 37.5mm and retained on 25mm sieve has flakiness index 11.58% while sample, which passed 25mm and retained on sieve 20mm has the flakiness index about 8.22%. This makes the average flakiness index become 6.6%. Aggregates that flaky could always lower the workability of concrete and also affects its long-term durability. In bituminous mixtures, flaky aggregates make for a harsh mix that can crack or break up during the compaction process.

CONCLUSION After carried out the test, the flakiness index of the collected sample is determined. By knowing the average index of about 6.6%, the sample collected is very suitable for bituminous mix. But, different bituminous mix may require different proportion of flaky aggregates. Therefore, appropriate manual should be referred in order to gain the right mixture of aggregates for an accurate bituminous mix.

13

APPENDIX 

Sieve (50mm, 37.5mm, 25mm, 20mm and pan)

 Sieve Shaker

 Balance machine

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>Metal gauge plate

REFERENCES  INTERNET o http://www.scribd.com/doc/48738827/Flakiness-Index 

TIME= 20.01 pm



DATE= 23/8/2012

o http://www.scribd.com/doc/60508812/Elongation-Index-Test 

TIME= 20.20 pm



DATE= 23/8/2012

o http://www.ele.com/euro/pdfs/aggregatespdf.pdf 

TIME= 20.40 pm



DATE= 23/8/2012

 BOOK o Highway Materials (A Guide Book for Beginners), Ratnasamy Muniandy, Radin Umar Radin Sohadi, Penerbit UPM, 2001. 

TIME=2100 pm



DATE= 26/8/2012

o Highway Engineering, Paul H. Wright, 6th edition, John Wiley & Son, Inc. 1996 

TIME=1000 am



DATE= 26/8/2012

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RUBRICS

Rating

Excellent 4

Good 3

Fair 2

Poor 1

C2: Introduction

Summarized procedure and purpose of work with relevant background information are sufficiently provided and the report are very well organized.

Summarized procedure and purpose of work with relevant background information are available but not completely provided. The report still well organized.

Summarized procedure and purpose of work with relevant background information are missing. Report is still reasonable well organized.

Summarize procedure and purposes of work with relevant background information are missing. Report is poorly organized.

C3: Data Collection and Recording

Data collected is clearly written and appropriately tabulated; Data is within the expected norms.

Data collected is improperly tabulated (units missing) or the data deviates appreciably from the expected norms.

Some data is missing and / or data deviates drastically from the expected norms.

Data is poorly organized or grossly incomplete

C4: Analysis (Calculations and Results)

All required calculations are present and performed correctly; Results (with % error where appropriate) are clearly stated.

All required calculations are present but minor errors are present in the calculations; Results section is incomplete (i.e. % error values are reported without the values they refer to).

Some calculations are missing and / or there are significant errors in the calculations.

Calculations are grossly incomplete and / or incorrect.

Pre-Lab Questions A3: Discussion/ conclusion

Varies depending on questions assigned, if any. All assigned questions (if any) are answered and discussed appropriately. Discussion of results shows a strong grasp of the scientific concepts covered by the lab.

All assigned questions are answered and discussed lightly. Discussion on results needs some refinement but shows a reasonably strong grasp of the scientific concepts covered by the lab.

Some assigned questions are answered. Discussion on results does not identify appropriate concepts, needs significant work and / or show a weak grasp of concepts.

Lecturer’s Name 16

All assigned questions are not answered. Discussion on results is inappropriate for the lab and shows a lack of comprehension of scientific concepts.

Lecturer’s Assessment

17