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