The document discusses aggregate gradation, defining it as the distribution of particle sizes and detailing the steps involved in gradation analysis through washed and mechanical sieve methods. It distinguishes between uniformly graded, well graded, and gap graded aggregates based on interlock and permeability. Additionally, it highlights the use of a (0.45 power) gradation chart and defines maximum size and gradation limits.

1. Aggregate Gradation-Part 1
Dr. Mutasem Alzoubaidi, Ph.D., P.E.

2. Gradation
• Definition:
– The distribution of particle sizes expressed as a percent of total
weight.
• Determined by sieve analysis

3. Steps in Gradation Analysis
Part 1 - Washed sieve analysis
– Dry aggregate and determine mass
– Wash and pour water through 0.075
mm sieve until water is clear
– Dry aggregate to a constant mass

4. Steps in Gradation Analysis
Part 2 - Mechanical sieve analysis
– Place dry aggregate in standard stack
of sieves
– Place sieve stack in mechanical
shaker
– Determine mass of aggregate retained
on each sieve

8. Gradation Terminology
* Uniformly graded
- Few points of contact
- Poor interlock (shape dependent)
- High permeability
* Well graded
- Good interlock
- Low permeability
* Gap graded
- Only limited sizes
- Good interlock
- Low permeability

9. Plotting a Gradation
• Use (0.45 Power) Gradation Chart
• Max Size Definitions
– maximum size
– nominal maximum size
• Gradation Limits
– control points
– restricted zone