To Determine the Particle Size Distribution of an Aggregate, and to Draw the Grading Chart

Sieve analysis

Objective:

To determine the particle size distribution of an aggregate, and to draw the grading chart.

Introduction:

The particle size distribution of an aggregate is determined by the mechanical analysis, which is usually made by shaking the material through series of sieves.

Sieves have square opening, in the testing in the concrete aggregate, there is generally employed a series of sieves in which any sieve in the series has twice the clear opening of the next smaller sizes in the series.

Grading chart:

The grading chart is the useful method of showing the grading of individual and combined in the following manner:

1.  Spacing between the sieve sizes be approximately equal to 10% on the vertical scale.

2.  The percentage of the aggregate coarser than a particle sieve size contributed by each individual aggregate is found by simply multiplying its corresponding ordinate by the percentage of the given aggregate to be used.

3.  Add the particle percentage so obtain for each sieve size to get the ordinate to the curve for the combined aggregate.

Standard:

B.S. 882

ASTM C-136

Apparatus:

·  Set of sieve.

·  Trays.

·  Oven capable of maintaining a uniform temperature of 110.

·  Brush.

·  Balance.

Calculation:

Wt. of sample = 1000g.

F.M = ∑( CUM . PER .RETAIND ) /100 =

(414.84)/(100) = 4.15 .

Discussion and conclusion:

-  We draw the grading chart to know if the aggregate is good, or not, and if the aggregate indicate the standard (B.S or ASTM). But there are some false in it, and we draw the chart, to know if the sample is well grading or not.

The result’s gives that the line is lower the standard lines and this make many errors in this experiment.

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