1.0
INTRODUCTION
The test is done in accordance with ASRM C131. The Los Angeles Abrasion Test is a measure of degradation of mineral aggregates of standard resulting from a combination of action including abrasion and grinding in a rotating steel drum containing a specified number of steel spheres. The number steel charges depend upon the amount and grading of test sample. As the drum rotates, a self plate picks up the sample and the steel spheres, carrying them until they are dropped to the opposite site of the drum creating an impact and crushing effect. The content then roll within the drum with an abrading and grinding action until the self plate impacts and the cycle is repeated. After the prescribed number of revolutions, the contents are removed from the drum and the aggregate portion is sieved to measure the degradation as percent loss.
OBJECTIVE
2.0
•
To obtain the Los Angeles number in the form of percentage wear of aggregates which reflects their resistance to degradation using the Los Angeles testing machine.
•
To ascertain the degradation of aggregates by abrasion and impact.
•
To determine the percentage of aggregates use in bituminous road surfacing.
•
To measure the hardness of aggregates that are recommended for use in highway projects.
3.0
THEORY
The Los Angeles test has been widely used as an indicator of the relative quality or competence of various sources of aggregates having similar mineral compositions. Specifications limit based on this test should be assigned with extreme care taking into consideration the aggregate type and their performance history in specific end uses. D>F Orchard suggest the following specifications using the LA value : a) The LA value value should should be equal equal to or or less than than 40% if aggreg aggregate ate is to be used used in concrete. For concrete wearing course lower values should be specified. b) The LA value value should should be equal to or or less than 45% 45% for road base base materials materials in lightly lightly trafficked road. The JKR Specification gives the following limits : a) Aggreg Aggregate ate for for use in in concr concrete ete – maxim maximum um 50% 50% b) Aggregat Aggregate e for used in bitumin bituminous ous road road surfacing surfacing – maximum maximum is 40% •
The test is an important tool to measure the hardness of aggregates that are recommend for use in highway projects. The test also will determine the quality of the aggregate. The soft aggregates will be quickly ground to dust, whilst the hard aggregates are quite resistant to crushing effect.
4.0
APPARATUS
The apparatus used in this test consists of : i.
ii.
iii.
Los Ange Angele less Ab Abras rasion ion Mac Mach hine. ine.
Metal tray
Sieves shaker
iv. iv. v. vi.
5.0
Siev Sieves es size sizess : 10mm 10mm,, 5mm 5mm,, 3.3 3.3mm mm,, 1.7 1.7mm mm and and pan pan.. Bala Balan nce (acc (accu urate rate to 0.01g .01g). ). Steel balls
PROCEDURE
6.0 RESULT RESULTS S
AGGREGATE SIZE (mm) 19-14 14-10
WEIGHT OF CRUSHED AGGREGATE (g) BEFORE (m1) AFTER (m2) LOSS (m3) 2500 2500
CALCULATION : LA ABRASION =
= 28.2 %
7.0 DISCUS DISCUSSIO SION N
4960
=2520-1110 =1410
% LOSS 28.2 %
1.
Los Angeles abrasion test A method for measuring abrasion resistance in which the sample and a set of steel spheres are tumbled inside a closed, hollow, steel cyclinder, about 700 mm diameter and 500 mm long, which is rotated on a horizontal axis.
2. Los Angeles Angeles abrasion abrasion test test studies studies all possib possible le reasons reasons causing causing wear. In the L.A. L.A. abrasion machine Attrition, Abrasion, and crushing are all present as follows: a. Attrition: Attrition: By the friction friction between between the aggregate aggregate particle particles. s. b. Abrasion: Abrasion: By By the frictio friction n between between the steel steel balls balls and the aggregates aggregates.. c. Crushing: Crushing: By hitting hitting the walls walls of the the testing testing machine. machine. 3.
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.
4. Los Angeles Angeles abrasion abrasion test test is suitable suitable for for coarse aggreg aggregate ate of different different sizes sizes and it it is not used for fine aggregate. 5.
The Los Angeles abrasion test is widely used as an indicator of relative quality of aggregates. Test measures degradation of standard gradings of aggregates when subjected to abrasion and impact, in a rotating steel drum containing an abrasive charge of steel balls.
6. Los Angeles Angeles Abrasion Abrasion Value (L.A.A. (L.A.A.V.): V.): Is obtain obtained ed from this this test and and it measures measures the wear of the material due to abrasion and attrition. 7. For this this experiment, experiment, the the LA Abrasio Abrasion n value obtain obtained ed was 28.2%. 28.2%. based based on on the JKR Specification, the aggregate for use in bituminous road surfacing is maximum 40%. So the value that was obtained is ok. The aggregate is suitable for all mixture. 8.
According to the specifications if Los Angeles Abrasion Value (LAAV) is equal to or less than 45% then this aggregate is suitable for all mixture for raod base materials in lightly trafficked road.
9. We get the the weight of of loss(m3) loss(m3) after after the aggregate aggregate was was finished finished it 500 500 rotation rotation in the the machine. The aggregate was sieve in sieve shaker until we get the aggregate in the pan. The weight of loss is the weight of aggregate on the pan.
8.0 CONCLU CONCLUSIO SION N
1.
Aggregates undergo substantial wear and tear throughout their life. In general, they should be hard and tough enough to resist crushing, degradation and disintegration from any associated activities including manufacturing, stockpiling , production , placing and compaction . Furthermore, they must be able to adequately transmit loads from the pavement surface to the underlying layers and eventually the subgrade. These properties are especially critical for open or gap graded HMA, which do not benefit from the cushioning effect of the fine aggregate and where coarse particles are subjected to high contact stresses .Aggregates not adequately resistant to abrasion and polishing may cause premature structural failure and/or a loss of skid resistance. Furthermore, poor resistance to abrasion can produce excessive dust during HMA production resulting in possible environmental problems as well as mixture control problems.
2.
The aggregate we used is suitable for use in bituminous road surfacing because the percentage is 28.2% which is less than 40%. The maximum percentage is 40% based on the JKR Specification.
3. The obje objecti ctive ve of the the experi experimen mentt was achiev achieved. ed. 4. The purpose purpose of of doing doing the LA Abrasi Abrasion on Test was was to determin determinee suitable suitable the percentag percentagee of aggregate that are used for concrete and bituminous road surfacing. The maximum aggregate used for concrete is 50% and 40% for bituminous road surfacing based on JKR Specification.
9.0 REFERENCE REFERENCE/APP /APPENDIX ENDIX
1. http://www. http://www.ahm53 ahm531.com/ 1.com/Lab_r Lab_rep/con ep/concrete/L crete/LA%20 A%20Abrasi Abrasion%2 on%20test. 0test.pdf pdf 2.
http://pavementinteractive.org/index.php?title=Los_Angeles_Abrasion
