Granular Base Stabilization with Emulsion in Las Vegas,

Nevada

Washington Avenue Rehabilitation Project

Todd Thomas, P.E. - Presenter

Authors Chris Finberg, City of Las Vegas

Department of Field Operations Dan Quire, Account Manager,

SemMaterials, L.P. Todd Thomas, Product Development

Engineer, SemMaterials, L.P.

Outline Purpose of the project Project description Existing conditions Laboratory evaluation Construction Observations Results

Purpose Provide structural capacity, saving

time and money relative to the alternative

Discuss technical aspects Discuss improvements

Project Limits

Rancho DriveM

artin

L. K

ing

Washington Ave.

0.8 Miles

Las Vegas, Nevada

Project Description2 Lanes in each direction, turn

lanes0.8 miles long (37,143 yd2)Mix of residential, small businesses,

a school and fire stationCurb and gutter15,500 AADT, 3% Trucks, TI = 9

Project DescriptionExisting asphalt was milled off in order

to stabilize the remaining aggregateHMA overlay over the emulsion-

stabilized base – match curb height

Existing PavementPavement Evaluation by Stantec

GPR – asphalt thicknessFWD – before and after

Existing SN = 3.0PQI = 6.5Layer Thickness

HMA: 4.5 to 7 inchesBase: 13.5 to 19.5 inches

Existing Pavement - BasePoorly graded sand or gravel with silty clay (fines PI of 6 or 7)Modified Proctor density of 145.2 pcf and OMC of 5.7%Passing No. 200 = 11.0%Material stabilized with asphalt emulsion – 5%

Existing PavementSubgrade

Symbol PI R-valueGC 28 18SM 9 35

CL-ML 7 13

ChallengesExisting base material was contaminated

– need for removalConventional design - remove and

replace18” agg base had to be removed18” of Type II had to be placedUtilities were 6” deep in the base

Construction Time (120 days) – Access and traffic delays

Asphalt Emulsion Provides flexibility and lower

susceptibility to cracking Binds the materials for improved

cohesion and strength Improved formulas that coat better

and build strength faster

Mix Design4, 5, 6, and 7% emulsion evaluated

5% used during construction4% water before mixing with emulsion

Superpave gyratory compactor – 150 mm mold, 30 gyrations

276,000 psi resilient modulus40 psi indirect tensile strength (dry)27 psi conditioned ITS

Construction Process

Construction Process

Construction Process

FDR Quality Control Moisture content Emulsion content Density Depth

Structural Comparison

6” HMA

18” Type II Aggregate Base

5.5” HMA

6” FDR

Total SN = 4.73 (from FWD)$925,685

Total SN = 4.50$1,248,346

7-12” existing Aggregate Base

Emulsion FDRTypical Reconstruction

Design SN = 4.35

FWD Results – Before and After

FDR AASHTO Layer Coefficient 0.28 per FWD testing. (HMA is typically 0.35 to 0.42)

Advantages

•$322,661 cost savings (30%)

•Construction time reduced from 120 to 40 days

•3,000 fewer loads of materials were trucked on and off the project

•Almost immediate traffic access to business

•Underground utilities weren’t affected

Chris Finberg (City of Las Vegas) – 702-236-4759

Dan Quire (SemMaterials, L.P.) – 303-915-2851

Todd Thomas (SemMaterials, L.P.) – 918-960-3828

Questions?