Saturday, March 24, 2012

Highway Laboratory

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Flakiness and Elongation Test (BS 812: Part 3)


1.0  Introduction

The type of rocks and the type of crushing machine highly determine the shape and size of the aggregates produced. Elongated and flaky stones are normally not very suitable for road works since the shape and the size make them difficult to compact. As such the flakiness and elongation test must be carried out to determine the suitability of the material.

2.0  Objective

To determine the flakiness index of aggregates.

3.0  Apparatus

a.    A metal gauge plate

Figure 3.1: A metal gauge plate


4.0  Methodology

a.    Three samples of aggregates weighing 2.5kg each are prepared.
                                          i.    Aggregates passing 50mm BS sieve and retained on 37.5mm BS sieve.
                                         ii.    Aggregates passing 37.5mm BS sieve and retained on 28mm BS sieve.
                                        iii.    Aggregates passing 28mm BS sieve and retained on 20mm BS sieve.
b.    Each sample is gauge in turn of thickness on metal gauge.
c.    The passing material of each sample is weighed.














5.0  Result


PASSING SIEVE
(mm)
RETAINED SIEVE
(mm)
SAMPLE

(kg)
PASSING

(kg)
RETAINED

(kg)
FLAKINESS INDEX
(%)
ELONGATION INDEX
(%)
20
14
1
0.2064
0
20.64
0
14
10
1
0.0956
0
9.56
0


X 100
 
Calculation
            Flakiness index (%) =        Nos. passing             
                                                  Total Nos. Aggregate

X 100
 
                                             = 0.2064
                                                     1
                                             = 20.64 %
           
            Average Flakiness Index (%) = Summation of all fractions
                                                                    No. of fractions
= 20.64 + 9.56
            2
= 15.1%

Elongation index (%) =        Nos. passing            
                                                  Total Nos. Aggregate

X 100
 
                                             =      0
                                                     1
                                             =  0%
           
            Average Elongation Index (%) = Summation of all fractions
                                                                    No. of fractions
=   0
     2
=  0%


6.0  Discussion

Road as one of land transportation infrastructure is very important in supporting the economic for both regional and national development. The quality of material for road construction will also influence the road performance. Asphalt concrete as one of road surface material is mainly influenced by the quality of aggregates since aggregate occupies 95% by weight in total mixture. Various shapes of aggregates might be occurred during crushing in the crushing plant starting from rounded to flaky and elongated aggregates. The JKR requirement is not exceed 20% to make sure that the aggregate are suitable for road construction materials.  

7.0  Recommendations

a.       The more sample weight more difficult to count the aggregate but we can calculated using the right calculation.
b.      Sample are not been forced to pass the metal gauge plate. It’s to make sure that we get the accurate data.
c.       We the process, we need to have different tray to make sure all aggregate counted and not missed.

8.0  Conclusions

The value that we get from this test is 15.1% for flakiness and not exceeds 20% the JKR requirement. Elongation value is 0% because the aggregate is rounded so no any retain value. Aggregate quality for road construction will also influence the road performance. The flakiness and elongation rocks are not suitable for road construction because this type of rocks will make the road surface not balance and easy to damage.

9.0  Reference

a.    Bambang I., Journal of the Eastern Asia Society for Transportation Studies, Vol. 6, pp. 1302 – 1312. Workability and Resilient Modulus Of Asphalt Concrete Mixtures Containing Flaky Aggregates Shape; 2005. Available from: URL: http://www.easts.info/on-line/journal_06/1302.pdf
b.    Muniandy R., Radin Umar Radin Sohadi. Highway Materials, A Guide Book For Beginners. University Putra Malaysia: Penerbit Universiti Putra Malaysia; 2010.
c.    Paul H.W., Karen K.D. Highway Engineering [Seventh Edition]. USA: John Wiley & Son; 2003.
d.    Construction Quality Assurance. Introduction. 1(1): [8 screen]. Available from: URL: http://www.durocrete.com/Flakiness.pdf




10.0               Appendix

Thursday, March 15, 2012

Polished Stone Value (PSV) (BS 812: Part 3)

Polished Stone Value (PSV) (BS 812: Part 3)

1.0 Introduction

The Polished Stone Value (BS 812: Part 3) Gives A Measure Of Resistance Of Road Stone To The Polishing Action Of The Pneumatic Tire. Under Conditions Similar To Those Occurring On The Surface Of The Road Where The Surface Of The Road Consists Largely Of Road Stone, The State Of Polish Of The Sample Will Be One Of The Major Factors Affecting The Resistance Of The Surface To Skidding. The Actual Relationship Between Polished – Stone Value And Skidding Resistance Will Vary With The Traffic Condition, Type Of Surfing And Other Factors. All Factors, Together With The Reproducibility Of The Test, Should Be Taken Into Account When Drawing Up Specifications For Road Works, Which Include Test Limit For Polished – Stone Value.

2.0 Objective

To Measure The Extent Of Aggregates In Wearing Course That Would Be Polished Under The Traffic Flow.

3.0 Apparatus

a)    An accelerated polishing machine, which shall be rigidly mounted on  firm, level and resilient base of concrete.


Figure 3.1: Polishing Stone Aggregate Tester

b)    Metal moulds for preparation of specimens.


Figure 3.2: Metal Moulds


c)    Friction Test.
d)    British Standard Sieve.


Figure 3.4: Sieve Size 9.25mm And 7.94mm

e)    Materials consisting of no. 36 corn emery and air-floated emery flour.


Figure 3.5: No. 36 Corn Emery Flour
  
4.0 Methodology

a)    Specimens Are Prepared As Shown In The Standard And The Particle Used Shall Pass The 9.52mm And Retained On The 7.94mm British Standard Sieve.
b)    Specimen Are Polished Using The Polishing Machine. Temperatures Are Within 27 Degree Celsius During The Polishing Period.
c)    Watered And The No. 36 Corn Emery Are Faded Continuously On The Road Wheel Within The Period Of 3 Hours. 
d)    After 3 Hours, The Machine And The Specimens Are Washed To Remove The Trace Of The Corn Emery.
e)    Repeat Step 2 With The Air Floated Emery Flour Replaced No. 36 Corn Emery The Rates Of Feeding Of The Water Are Twice For The Emery Flour.
f)     The Specimens Are Stored Facing Downwards Under Water At A Temperature Of 25 Degree Celsius For ½ To 2 Hours.
g)    After That, Specimen Are Removed From The Water And Tested On The Friction Tester.
h)   The Specimen And The Rubber Slider Are Wetted Before The Frictions Are Done.
i)     The Pendulums Are Released From Its Original Position (Horizontal) And Readings Are Taken From The Pointer.



5.0 Result

Polished Stone Value (PSV) (BS 812: Part 3)

Specimen
Specimen No
Polished – Stone Value
1            2            3           4             5
Mean
1
1
49          48          49         47           48
48.2
2
2
54          55          54         53           54
54.0
3
3
48          48          49         48           48
48.2
4
4
53          51          51         50           50
51.0
13
13
52          52          52          53          53
52.4
14
14
52          52          52          51          52
51.8

Mean = 52.1


Polished Stone Value (P.S.V) = S + 52.5 – C
                                                     = 50.35 + 52.5 – 52.1
                                                     = 50.75


6.0 Discussion

a)    Aggregate must need to be the right chosen because need to place in the metal mould nicely.

b)    Need so much used of water.

c)    Must have 14 specimens to complete wheel of polish stone aggregate tester.

d)    Portable skid tester must be balance place to avoid the error measure reading.


7.0 Recommendations

a)    Nice not so rounded aggregate have chosen to be place in the metal mould.

b)    Water is used in making the specimen and to wet the specimens.

c)    Specimens can be from different types of rocks.

d)    Portable skid tester has to be balance using air bubble to get the balance portable skid tester.

8.0 Conclusion

From the experiment, we get the value is 50.75 more than the requirement of JKR’s; 40. This specimen are not manage to handle the heavy raining or flood because the skid value are mild and near to 40. The more skid value is better because it’s affecting the resistance of the surface pavement and tire. These relationships are varying with the traffic condition, type of surfacing and other factors. We can conclude this experiment successful because the value are exceeding the JKR’s requirement, <40. 


9.0 Reference:

a)    Accelerated Polishing Machine. 1(1): [1 screen]. Available from: URL:  http://www.capco.co.uk/acatalog/Online_Catalogue_Accelerated_Polishing_Machine_18.html

 

b)    MASTRAD Quality abd Test Systems. Test Procedures and Equipment. 1(1): [7 screen]. Available from: URL: http://www.mastrad.com/psvdoc.htm

 

c)    WRAP Material Change for a better Environment. Polished Stone Value. 1(1): [1 screen]. Available from: URL:  http://aggregain.wrap.org.uk/terminology/polished_stone.html

 

d)    Nanyang Technological University, School of Civil and Structural Engineering. Skid Resistance Test. 1(1): [7 screen]. Available from: URL: http://www3.ntu.edu.sg/cts/tlab/006.pdf

 

e)    Muniandy R., Radin Umar Radin Sohadi. Highway Materials, A Guide Book For Beginners. University Putra Malaysia: Penerbit Universiti Putra Malaysia; 2010.

 

f)     Paul H.W., Karen K.D. Highway Engineering [Seventh Edition]. USA: John Wiley & Son; 2003.


Soundness Test (ASTM C88)

Soundness Test (ASTM C88)

1.0  Introduction

The soundness of aggregates or their resistance to the forces of weathering is undoubtedly one of the most important considerations in the selection of a material for highway construction. The primary exposure that one is concerned with is alternate freezing and thawing. Somewhat less frequently one may be concerned with resistance of materials to alternate heating and cooling, wetting and drying or the action of aggressive waters.

The most common soundness requirement for aggregates, (coarse and fine) is based on a sodium or magnesium sulfate soundness test (ASTM Designation C88-55T).

The method may be used for acceptance of material but rejection should be based on other determinations such as freezing and thawing tests. Freezing and thawing tests of aggregate are also commonly used as the basis for a soundness specification. No ASTM test method exists for this, although there is an AASHTO standard method in existence (T 103-42).

2.0  Objective

a.    To determine the resistance of aggregates to disintegration by saturated solution of sodium sulphate.
b.    To measure the resistance of aggregates to cycle of freezing and thawing.
c.    To judge the soundness of aggregates subject to weathering action.
  
3.0  Apparatus

a.    Containers
Figure 3.0.1: Container

b.    Balance (accurate to 0.01g)

Figure 3.0.2: Balance

c.    BS Sieve with square openings.

Figure 3.0.3: BS Sieve







d.    Oven
Figure 3.0.4: Oven

3.1 Materials
a. Coarse aggregates.
Figure3.1.1: Coarse aggregate in various sizes.
b.  Clean water.
Figure3.1.2: Clean water.

c.    Sodium sulphate.
Figure 3.1.3: Sodium sulphate solution.



4.0  Methodology

a.    Sample of coarse aggregate washed with clean water and dried at 105º – 110ºC.  Samples are separated into different sizes by sieving to refusal. Samples weighed till 1kg and separated and place its in container for the test.
b.    Sample was immersing for sodium sulphate solution for approximately 18 hours to make sure the solution cover the depth of at least ½ inch.
c.    After immersing period, aggregate sample are removed from the solution and dried for 15  5 min and placed in drying oven for 105º – 110ºC. Sample is dried at specified temperature until constant weigh achieved.
d.    After that, sample is cool at room temperature and immersed in prepared solution.
e.    Process of alternate immersion are repeated and dried for 5 days.   
f.     Sample is washed from sodium sulphate after completion the final cycle and sample is cooled.
g.    Sample is dried at 105º – 110ºC the each fraction of the sample is weighed.
h.    Average weighted is calculated from the percentage of loss for each fraction.  

5.0  Result

Calculation

Percentage of loss = [weight of sample before testing – weight of sample after testing]
                                                     Weight of sample before testing
1- 0.9977 x100%
      1
= 0.23%
Total soundness loss of the sample = summation of loss of all fractions
          = 0.23 + 0.90 + 1.25
          = 2.38%

6.0  Discussion

In this study, the mechanisms of damage aggregate by sodium sulfate solutions were investigated. This experiment measure the resistance of aggregates to disintegration by saturated solution of sodium sulphate. Experiment is due to the type of season in Malaysia. Raining all the year is similar with snowy season area. This experiment is to ensure that the aggregates are tough enough to handle the water in gaps of the road. Road can be damaged or crack if the weathering process continuously. JKR requirement are not less than 12% for 1 size of aggregates. For 5 size the accumulate percent are 20% according to the JKR requirement.

7.0  Recommendation

a.    During the drying period, sample is removed from oven, cool to room temperature and weighed at time intervals of not less than 4 hour and not more than 15 hour.
b.    Constant weight is considered had been achieved for differ 1.0g for coarse aggregate samples.
c.    Container is covered to reduced evaporation and prevents accidental addition of extraneous substances.
d.    Sample are maintained immersed in the solution at a temperature of 21 1ºC.


8.0  Conclusion

We can conclude that the total soundness loss is loss than the requirement of JKR. The JKR requirement is less than 12% and the result is 2.38%. The aggregate value and the physical properties are acceptable.  These aggregate can handle the situation in Malaysia. Even this experiment is recommended for snow area. Malaysia still can do the experiment because Malaysia had all year raining seasons. 

9.0  Reference

a.    Muniandy R., Radin Umar Radin Sohadi. Highway Materials, A Guide Book For Beginners. University Putra Malaysia: Penerbit Universiti Putra Malaysia; 2010.
b.    Paul H.W., Karen K.D. Highway Engineering [Seventh Edition]. USA: John Wiley & Son; 2003.
c.    Haynes H., ASTM C 88 test on soundness of aggregate using sodium sulfate or magnesium sulfate: A study of the mechanisms of damage. Available from: URL: http://www.mendeley.com/research/astm-c-88-test-on-soundness-of-aggregate-using-sodium-sulfate-or-magnesium-sulfate-a-study-of-the-mechanisms-of-damage/
d.    ASTM C88 - 05 Standard Test Method for Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate. Available from: URL: http://www.astm.org/Standards/C88.htm

10.0               Appendix


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