Airport Pavement &

Aggregate Crushing

Presented by Kristen Blake, Shelby Brevogel, Lauren Hillis,

Nate Rahaim, and Andrew Short

Under the micromechanics of crushing by considering individual particle crushing strengths and triaxial shear tests on laboratory scale samples

Model the densification of the soil layers under airport pavements using the gyratory compactor and compare results to field compaction

Objectives

Leonards, 1995

Large Scale Versus Small Scale

Super Gyratory Compactor

Field Trafficking

versus

Past Work

Data acquisition from FAA testing facility

Effort to replicate data within the laboratory

Computations to create a comprehensible relationship

Current WorkConcentration on P-154

Energy Relation Determination

Density and Energy Calculations

•Energy based approach

•Reason being crushing in sub layers

Background

- When particles break, it will break into similar shapes as the original particle

- Higher coordination # will result in large particles breaking

McDowell (1996)

- Particles eventually reach a stable gradation, once the crushing of particles result in decreased volume

Coop (2004)

Equipment

•Skyscan 1072 micro-CT•Triaxial Compression Test

Particle Crushing

Concrete Sand in crushing Calcareous Sand in Crushing

Triaxial Compression Tests

Soil Properties

Sand Gs emax emin

D50 (inches)

Φ (degree

s)

Concrete 2.64 0.74 0.47 0.0270 34

Ottawa 2.65 0.86 0.5 0.0185 32.7Calcareous 2.73 1.014 0.77 0.0175 -

Soil Failures

50 60 70 80 90 100 110 120 130 1400

20

40

60

80

Ottawa Sand Stress Path

q' (psi)

p' (p

si)

10 15 20 25 30 3505

10152025

Ottawa Sand Stress Path

q' (psi)

p' (p

si)

Goals

Publish energy relation findings

Determine inherent soil properties and crushing characteristics for Calcareous Sands from Triaxial tests

Create Discrete Element Models of sand samples

Questions?