Aggregate impact value Calculation And uses
- 1. Created by Shahryar & CO.
- 2. This test is done to determine the aggregate impact value of coarse aggregates AIV is basically a % ratio of 2.36mm sieved aggregate to 14mm aggregate sieve. The apparatus used for determining aggregate impact value of coarse aggregates is Impact testing machine Sieves of sizes – 14mm, 10mm and 2.36mm,a cylindrical metal measure of 75mm diameter and 50mm depth, A tamping rod of 10mm circular cross section and 230mm length, rounded at one end.
- 3. It is usually used to tamp the aggregate so that it should acquire all the empty space of metallic cup. Its diameter is 10mm and it is 230 mm in size . Tampin g Rod
- 4. A sample of aggregate containing element of different sizes for the experiment. Coarse aggrega te
- 5. Sieves of sizes 14mm,10m m and 2.36mm must be available. Sieves of Differen t sizes
- 6. A cylindrical cup of diameter 75mm and cross section 30mm length. Cylindri cal Cup
- 7. A digital weight calculation machine is also a part of the experiment. Weight Calculating Machine
- 8. An average aiv machine must have following properties 1-mass variable up to 13.6 kg 2-impact energy variable up to 132.8 J 3-impact velocity up to 4.4 m s 4-its hammer diameter is 70mm AIV Calculating Machine
- 9. First of all set all the sieves according to the following order:- 14mm>10mm>2.36mm or 14mm sieve on the top and 2.36 sieve at the bottom. Pass the given amount of aggregate through the sieves according to given order. Collect the aggregate which passes through 14mm sieve and retained on 10mm sieve. This aggregate is known as Coarse aggregate. Take the metallic cup and weight it .Let its weight is W. Now fill 1/3 of the cup with coarse aggregate and tamp it with at least 25 tamps of tamping rod. Repeat the whole procedure 3 times so that all the empty space of cup should be completely filled with aggregate. Weight the cup let it must be W1 Carefully place the cup beneath the hammer of the aiv machine. Hammer it with 15 strokes of machine hammer. Pass the retained aggregate through 2.36 sieve. Calculate the weight of passed aggregate let it be W2
- 10. After calculation we can find aiv % by given formula AIV % = (W1-W/W2) x 100 APPLICATION S OF AIV Aggregate having AIV % less 50% is better to use in construction where as those having value more than 50% are bad for construction. It is reliable to calculate the AIV % of the aggregate use as road metal as it will give us the capacity of road to bear the load on it. Aggregate having AIV % equal or greater than 35 % is considered bad to use in road construction.