TEST FOR GRADING OF AGGREGATE

AIM :- To determine the various size of aggregates.

APPARATUS :- Indian standard test sieves, weighing balance ,sieve shaker etc.

Size of sieves to be used :-

1. For fine aggregate - 4.75 mm, 2.36 mm, 1.18 mm, 600 microns, 300 microns, 150 microns.

2. For course aggregate - 25 mm, 20 mm, 12.5 mm, 10 mm, 4.75 mm.

PROCEDURE :-

For Fine Aggregates

1. Take 1kg of sand from the laboratory sample.
2. Arrange the sieves in order of IS sieves no’s 480, 240, 120, 60, 30 and 15, Keeping sieve no.480 at the top and 15 at the bottom and cover the top.
3. Keep the sample in the top sieve no.480.
4. Carry out the sieving in the set of sieves for not less than 10 minutes.
5. Find the weight of sample retained in each sieve.
6. Arrange the values in given column .

For Coarse Aggregates

1. Take one kg of coarse aggregate
2. Arrange the sieves one over the other in relation to their size of opening.(25 mm, 20 mm,12.5 mm, 10 mm, 4.75 mm)
3. Carry out the sieving for the specified time
4. Find the weight of aggregate retained on each sieve taken in order and tabulated in table.

• Plot the Graph

Draw a graph with sieve opening to log scale on the X-axis and % finer on Y-axis .The curve iscalled a grading curve.

• Calculations in Grain Size Analysis

For Fine Aggregates

1. Effective size in microns (Di0 sieve opening corresponding to 10%finer in the graph ) =
2. Uniformity coefficient (D60/ D10),D to be obtained from the graph ) =
3. Fineness modulus (Sum of cumulative % wt retained /100) =

For Coarse Aggregates

1. Effective size in microns (D10,sieve opening corresponding to 10% finer in the graph)
2. Uniformity coefficient (D60/ D10),D to be obtained from the graph ) =
3. Fineness modulus (Sum of cumulative % wt retained /100) =

• Results of Grain Size Analysis

For Fine Aggregates

1. Effective size =……………..micron
2. Uniformity coefficient =
3. Fineness modulus =

For Coarse Aggregates

1. Effective size =……………..micron
2. Uniformity coefficient =
3. Fineness modulus =