Los Angeles Abrasion Test

Los Angeles Abrasion Test (ASTM C131)

1. Objective

To ascertain the degradation of aggregates by abrasion and impact.

2. Introduction

The Los Angeles (L.A.) abrasion test is a common test method used to indicate aggregate toughness and abrasion characteristics. Aggregate abrasion characteristics are important because the constituent aggregate in HMA must resist crushing, degradation and disintegration in order to produce a high quality HMA. The standard L.A. abrasion test subjects a coarse aggregate sample (retained on the No. 12 (1.70 mm) sieve) to abrasion, impact, and grinding in a rotating steel drum containing a specified number of steel spheres. After being subjected to the rotating drum, the weight of aggregate that is retained on a No. 12 (1.70 mm) sieve is subtracted from the original weight to obtain a percentage of the total aggregate weight that has broken down and passed through the No. 12 (1.70 mm) sieve. Therefore, an L.A. abrasion loss value of 40 indicates that 40% of the original sample passed through the No. 12 (1.70 mm) sieve. The standard Los Angeles abrasion test is: AASHTO T 96 or ASTM C 131: Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine 

1

3. Apparatus

Figure 3.1: Los Angeles Abrasion machine (Plate 2)

Figure 3.2: Sieves (19mm, 12.5mm, 9.5mm, 1.7mm and Pan)

Figure 3.3: Sieve Shaker (Plate 3)

Figure 3.4: Electronic Balance (accurate to 0.01g)

2

4. Methodology a. Sample are weight up to 2500g for every size; 14 – 12.5mm and 12.5 – 9.5mm b. Samples are placed in Los Angeles Abrasion Machine. c. Eleven steel balls are added in the machine. d. The drum is rotated for about 500 revolutions at 30 – 33 rpm. e. Sample is removed from the drum and sieved on no. 12 sieve after being rotated. f. The retained sample on the sieved is washed and dried at the temperature of 105 to 110ºC.After the sample cool down, weight of the sample are taken.

Procedure 3

Step 1

Step 2

Step 4

Step 3

Step 5

Step 6

5. Result 4

Aggregate Size

Weight Of Sample

(Mm) 14-12.5 12.5-9.5

Before (Kg) 2.5 5.0000

Weight Of Sample

Loss

After (Kg) 3.9511

(Kg) 1.0489

2.5

Percent Wear (Average)

1.0489 X 100 5

20.98%

Calculation Weight loss

= (Weight of sample before abrasion) – (Weight of sample after abrasion) = 5.0000 – 3.9511 = 1.0489kg

Percent wear = =

x 100 x 100

= 20.98%

6. Discussion

5

During the experiment, many factors can influence the data obtained. The factors are outlined below: a) Different data will be collected when the weighting process because of wind resistance. The sample data may be higher or lower than the reading data because of the reading error. b) Drum must be clean before using because its may affected the weight of the sample. It’s because dust from previous project will affect the reading of the scale. c) The condition of the machine may also affect the sample weight. Because of that

the small aggregates will escaped from the machine. Sample may escape from the open window. d) Only 10 steel balls are been used may cause different data from the actual experiment. Steel balls are used to abrasion and impact the aggregate when the drum is rotating. Aggregate will broken to smaller size that will represent the percentage of the total mass of aggregate. The data may be slightly different than that we had obtained. Even though this experiment have a problems as stated above, the value of aggregate physical property requirement still not exceeded as what the JKR had stated in the Table 1.1.

7. Recommendations 6

All the problems stated above can be solved if these precautions have been taken. These all are listed below: e) Laboratory must been closed area especially at the measuring area to avoid the

wind resistance affected the weight data or closed box of measuring machine. f) After doing the experiment, all the apparatus must been clean and keep at the clean

place to avoid any dust entering the apparatus.

g) Machine must do the maintenance regularly. All the damages must be repaired

before being used by student. Its also can avoid accident in laboratory. h) The accurate amount of steel balls will make the collected data more efficient. The sample will break into what we supposed to get.

8. Conclusions

From the experiment, we get the value is 20.98% less than the requirement of JKR’s; 30%. Aggregate physical property are lower Los Angeles abrasion is tougher and more resistance to abrasion. We can conclude that the aggregate been used are medium tough and not more resistant to abrasion. It’s because the value are more than half than JKR’s requirement. Lower Los Angeles abrasion loss values indicate aggregate that is tougher and more resistant to abrasion.

9. Reference

7

a. Celeste Hoffman. Los Angeles Abrasion. 2007 December 15; 1(1): [11 screen]. Available from: URL: http://pavementinteractive.org/index.php? title=Los_Angeles_Abrasion

b. University of New Mexico, Civil Engineering Department, Civil Engineering Materials Laboratory, CE 305L. Resistance to Degradation Of Small-Size Coarse Aggregate By Abrasion And Impact In The Los Angeles Machine [Astm C131]. 1(1): [3 screen]. Available from: URL: http://civilx.unm.edu/laboratories_ss/pcc/laabrasion.html

c. Ahmed Essam Mansour. Los Angeles Abrasion Test. ; 1(1): [3 screen]. Available from: URL: http://www.ahm531.com/lab-reports/concretelab/reports/1/LA%20Abrasion%20test.pdf

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

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

8