Aggregate Impact Value 1u186f

Aggregate Impact Value (BS 812: Part 3) 1. Objective

To determine the aggregate impact value in the laboratory

2. Introduction

Impact value of an aggregate is the percentage loss of weight particles ing 2.36mm sieve by the application of load by means of 15 blows of standard hammer and drop, under specified test condition. The aggregate impact value gives a relative 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.

3. Apparatus a. Impact testing machine: i. A cylindrical hammer of 13.5kg (30 lbs) sliding freely between two vertical s (guides). ii. Falls automatically adjusted to the height of 38cm. iii. There is a brass plate over which an open cylindrical steel cup of internal diameter 10.2cm and 5cm depth placed and fixed to the brass plate.

Figure 3.1: Impact Testing Machine

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b. Tamping rod of 1cm diameter and 23cm long rounded at one end and pointed at the other end.

Figure 3.2: Tamping Rod

4. Methodology a. Samples are weighted up to 600g. b. The aggregate of size 12.5 – 9.5mm are filled in the cylindrical measure in 3 layers lapped using tamping rod for 25 times. Straight edge was used as the level of surface tamping rod. c. The cylindrical measure was transferred to the brass plate. d. Hammer was released to fall freely on the aggregate and 15 blows are subjected to a total of the test sample. e. Samples were sieved by 2.36mm sieve after removed from cup. f. Weights of retain ad ing were measured.

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Procedure

Step 1 Step 2

Step 3

Step 5

Step 4

Step 6

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5. Result

Sample

Weight Of Size

Weight Of Sample

Weight Of Sample

Percent Wear

A B C

(Mm) 12.5 – 9.5 12.5 – 9.5 12.5 – 9.5

Before Crush (G) 600 600 600

After Crushed (G) 41.60 59.20 54.90

(%) 6.93 9.87 9.15

Percent Wear (Average)

8.65%

Calculation Percent wear = Weight of sample after crushed Weight of sample before crushed

x 100

= 41.60 x 100 600 = 6.93%

6. Discussion

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The experiment indicated a few improvements to the problem state:

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) Beside that, the distance of the person hand while tamping may cause different result. Tamping layer also can affect the error reading because it’s done manually and not consistence with the others. c) The brass plate are not closed may cause reduction to the weight of sample after being crushed. The aggregate will fall out from brass plate because of the hammer was released freely and fall on the aggregate. The height of hammer and brass plate can also be the factor to the error data.

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

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These are the precaution or improvement that can we make: a) 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. b) Second, to avoid error to the sample data. Only one person with consistence strength and distance can reduced the error. It’s more effective if can be doing using a machine than manually. c) The brass plate must been in closed machine to make sure that the sample not

fall out from brass plate. Hammer must in same size with the brass plate to ensure that the aggregate are crash accurately.

8. Conclusions From the experiment, we get the value is 8.65% less than the requirement of JKR’s; 15%. Aggregate physical property must lower Aggregate Impact Value, AIV because is tougher and resistance to crushed. We can conclude that the aggregate been used are medium tough and resistant to be crash. It’s because the value are more than half than JKR’s requirement. These experiments are successful because its still not exceed the JKR’s requirement.

9. Reference

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a. Civil Engineering Sri Langka. Aggregate Impact Value Test. 2010 December 31; 1(1): [5 screen]. Available from: URL: http://goda02.com/aggregate-impact-value-test

b. MASTRAD Quality and Test System. Aggregate Impact Value.; 1(1): [2 screen]. Available from: URL: http://www.petroleum-test.com/aiv.htm

c. Determination of Aggregate Impact Value.; 1(1): [8 screen]. Available from: URL: http://theconstructor.org/building/buildingmaterial/determination-of-aggregate-impact-value/1355/

d. Civil Engineering Portal. 1(1): [5 screen]. Available from: URL: http://www.engineeringcivil.com/aggregate-impact-value.html

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.

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