Aggregate Impact Value.pdf 655p58

Faculty : Faculty of Civil and Environmental Engineering Department : Department of Infrastructure and Geomatic Engineering Title : AGGREGATE IMPACT VALUE 1.0 INTRODUCTION Impact value of an aggregate is the percentage loss pf weight of particles ing 2.36mm sieve by the application on load by mean of 15 blows of standard hammer and drop under specified test condition. The aggregate impact value gives a relation measure of the resistance of an aggregate to sudden shock or impact, which in some aggregates differs from their resistance to a slowly applied compressive load. General: Normally the aggregate impact value of base course is 30, bituminous bound macadam is about 35 and the cement concrete base course is 30. Significance: The test gives an idea of toughness of the aggregate to resist facture under the impact of moving loads.

2.0 OBJECTIVE To determine the aggregate impact value in the laboratory.

3.0 APPARATUS 1. Impact Testing Machine: Its consists of a cylindrical hammer of 13.5 kg. (30Ibs) sliding freely between two vertical s (called guides). Its fall is automatically adjusted to a height of 38cm. There is a brass plate over which an open cylindrical steel cup of internal diameter 10.2cm and 5cm depth is placed and fixed to the brass plate. 2. Measure: A cylinder of internal diameter 7.5cm and 5cm deep for measure aggregate. 3. Tamping rod of I cm diameter and 23cm long rounded at one end and pointed at the other end. 3. Sieves: 12.5mm, 10mm and 2.36mm opening. 4. Balance: 5000g capacity. 5. Laboratory oven capable of maintaining a constant temperature up to 110ºC

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Faculty : Faculty of Civil and Environmental Engineering Department : Department of Infrastructure and Geomatic Engineering Title : AGGREGATE IMPACT VALUE Apparatus for the Aggregate Impact Value Test (Millard, 1993)

4.0 PROCEDURE 1. Sieve the aggregate and obtain the portion ing 12.5mm and retained on 10mm sieve. 2. Wash and dry this aggregate at a constant temperature of 1050C to 1100C and then cool the sample. 3. Fill this aggregate in the cylindrical measure in 3 layers, tapping each layers 25 times with the tamping rod. Level the surface tamping road as a using the straight edge. 4. Weight the aggregate in the measure. This weight of the aggregate is used for the duplicate test on the same material. 5. Transfer the aggregate from the cylindrical measure to the cup in 3 layers and compact each layer by tamping in 25 strokes with the tamping rod. 6. Release the hammer for fall freely on the aggregate. The test sample is subjected to a total of 15 blows. 7. Remove the aggregate sample from the cup and sieve through 2.36 mm sieve. 8. Weight the fraction ing the sieve. 2

Faculty : Faculty of Civil and Environmental Engineering Department : Department of Infrastructure and Geomatic Engineering Title : AGGREGATE IMPACT VALUE 5.0 FORMS AND CALCULATION

Sample

Weight of cup (gm)

Weight before crush (gm)

Weight retained 2.36 mm sieve (gm)

Weight ing 2.36 mm sieve (gm)

A B Average

Percent Wear (Average) = _Weight Loss_ Initial Weight

χ 100

Percent Wear (Average)

Checked by ; ……………………………………..

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Date :…………………………..

Faculty : Faculty of Civil and Environmental Engineering Department : Department of Infrastructure and Geomatic Engineering Title : AGGREGATE IMPACT VALUE 6.0 DISCUSSION a) Determine wheather the aggregate tested meets Malaysian Standard requirement . b) Discuss three precautionary measures taken during the experiment.

7.0 CONCLUSION

Ref : BS 812-112 1990 4