5.3 : Sieve Analysis and Grading Curves

Sieve analysis is a method used to determine the particle size distribution of aggregate materials. This process involves the following steps:

1. The required quantity of dried sample of aggregate is weighed.
2. The weighed aggregates are sieved through a set of sieves with square openings arranged in descending order of aperture size, with the largest mesh on top (Column 1 of Table 1).
3. The stack of sieves is shaken or vibrated to facilitate the sorting of particles by size.
4. After sieving for a specific period, the material retained on each sieve is weighed (Column 2 of Table 1).
5. The weight of particles retained on each sieve is expressed as a percentage of the total sample mass (Column 3 of Table 1).
   
6. The cumulative percentage passing each sieve is calculated to the nearest one percent from the finest sieve moving upwards (Column 4 of Table 1).
7. The grading curve is plotted on a graph (Figure 1) where the ordinate values represent the percentage passing (Column 4 of Table 1), and the abscissa values show the sieve apertures (Column 1 of Table 1), set to a logarithmic scale.

Table 1: Data for sieve analysis on sand

Grading curves visually simplifies the distribution of particle sizes and is essential for ensuring that aggregates meet the required grading specifications for construction projects.