LTRC

Settling the Dust with Environmental Compliance – Cement Slurry • Gavin Gautreau, P.E. Senior Geotechnical Research

Engineer • Khalil Hanifa, E.I. Geotechnical Research Engineer

Intern

Overview

• What’s the problem?

• Applications

• Example project

• New Product Evaluation (NPE) Process

• Brief overview of new Specification Book

• Implementation

• Conclusions

• Closing and Questions

What’s The Problem?

Contractor means and methods control dust while the project is under their ownership/construction.

Dust control methods are not currently specified by DOTD. However…Occasionally conditions dictate specific dust control requirements and needs be met.

A ground treatment the department can specify to meet both strength and dust requirements is needed.

Soil modification via dry additive

• Treatment or Stabilization

of subgrades and bases

•Cement

•Lime

•Slag Cements

• Remote vs. urban

• Spreader boxes can help,

but are uncommon, still dry.

Multiple Trucks on new, remote road.

Applications

How dust might cause problems:

• Safety

• Visibility, maintaining sight lines

• High traffic areas, higher risk areas, turns, etc.

• Environmental

• Wind blown into sensitive areas, businesses, etc.

• Legal issues and costly repairs

• High traffic areas (Vehicles Damage)

• Urban areas (Building Damage)

• Historical Structures

Mandeville Example Project

• State Project No. 013-12-0032, US 190 (LA 22 to Bayou Castine)

• Typical Section

2” Superpave Asphaltic Concrete Wearing Course (Level 2F)

3” Superpave Asphaltic Concrete Binder Course (Level 2)

4” Superpave Asphaltic Concrete Base Course (Level 2)

10” Class II Base Course 1. 10” Crushed Stone or Recycle PCCP

2. 6” Soil Cement w/ 4” Stone

Geotextile Fabric (Class D)

12” Lime Treatment (Type D)

2” Superpave Asphaltic Concrete Wearing Course (Level 2F)

3” Superpave Asphaltic Concrete Binder Course (Level 2)

4” Superpave Asphaltic Concrete Base Course (Level 2)

10” Class II Base Course 1. 10” Crushed Stone or Recycle PCCP

2. 6” Soil Cement w/ 4” Stone

Geotextile Fabric (Class D)

12” Lime Treatment (Type D)

The “Sand Burrito” alternative

“Encapsulated Sand”

no longer treated soil.

• Excavate poor subgrade

• Place geosynthetic

• Place sand on and wrap

Why better

than just

cement and

water

It takes a lot of effort.

Excavation Alternatives

• Cost Differences

• Time Differences

Mandeville Problem – Base #1

Base Course called for 4” Asphaltic Concrete

Due to poor sub-base (the layer below) it had to be put in with a dozer.

It later proved to be an insufficient riding surface

Mandeville Problem – Base #2

A slurry cement would have been a great alternative solution to

manage dust while meeting the soil’s needs. …for the subgrade

and base course layers in this silty urban area.

10” Blended Calcium Sulfate (BCS) was installed

• Built near water table

• On encapsulated sand

• BCS is moisture sensitive similar to pumping silts.

• Therefore more problems, but eventually resolved.

New Product Evaluation Committee

New Product Evaluation (NPE) Process

• The New Product Evaluation Committee’s function is to provide for the structured review, evaluation and implementation of new products and procedures submitted to the Department.

• Cement Slurry evaluated under Category 17. Stabilizing Materials by Soil Stabilization Subcommittee

• 3 Phase Evaluation Process Developed by Mark Morvant, LTRC

Phase 1 Results

• Phase 1 Submittal Form

-Vendor’s Product Information Material Composition

-Set Retarder

-Plasticizer

Cost

Capabilities

Benefits

Etc.

Phase 1 Results

Phase 2 Results

• Phase 2 Test Program Established by Subcommittee

1. Independent Laboratory Results Confirms Capabilities Made By Vendor

2. LTRC Verification Testing Confirms Results of Independent Lab Results

Builds Confidence of Subcommittee

Builds Confidence of Department

Validates Need for Phase 3 Test Sites

Phase 3 Results

• State Project No. H.008038.6, LA 405

Phase 3 Results

• In-Place Cement Treated Base Course (150 psi goal)

-Project Engineer Initiated Use of Cement Slurry

-Nottoway Plantation (Historic Structure)

Phase 3 Results

Phase 3 Results

7-Day Strengths 28-Day Strengths

LA 405 Field

Samples 8% Super

Slurry

STA 82+00

145.3 psi

135.7 psi

(Average)

175.0 psi

177.8 psi

(Average) 114.8 psi 162.8 psi

146.9 psi 195.5 psi

STA 87+00

59.7 psi

64.2 psi

(Average)

103.7 psi

150.1 psi

(Average) 53.0 psi 164.6 psi

79.9 psi 182.0 psi

STA 88+00

168.4 psi

176.2 psi

(Average)

225.9 psi

233.9 psi

(Average) 187.7 psi 241.9 psi

172.5 psi --

Phase 3 Results

• State Project No. H.010531, LA 1148 • In-Place Cement Treated Base Course (150 psi goal)

Phase 3 Results

7-Day Strengths 28-Day Strengths

LA 1148 Field

Samples 6% Cement

STA 128+00

115.7 psi 116.7 psi

(Average)

87.7 psi 136.0 psi

(Average) 124.1 psi 162.1 psi

110.2 psi 158.3 psi

STA 132+00

170.7 psi 141.9 psi

(Average)

158.6 psi 119.5 psi

(Average) 155.9 psi 88.9 psi

99.0 psi 111.1 psi

STA 134+00

156.5 psi 159.5 psi

(Average)

169.4 psi 189.7 psi

(Average) 136.9 psi 219.0 psi

185.1 psi 180.6 psi

LA 1148 Field

Samples 6% Super

Slurry

STA 138+00

153.6 psi 188.2 psi

(Average)

285.6 psi 293.1 psi

(Average) 182.6 psi 307.4 psi

228.5 psi 286.4 psi

STA 139+00

201.2 psi 170.9 psi

(Average)

184.9 psi 148.9 psi

(Average) 192.1 psi 139.7 psi

119.4 psi 122.2 psi

STA 141+00

152.1 psi 148.0 psi

(Average)

208.9 psi 165.2 psi

(Average) 143.3 psi 142.8 psi

148.6 psi 143.9 psi

STA 141+50

287.2 psi 302.3 psi

(Average)

247.7 psi 246.7 psi

(Average) 307.8 psi 256.7 psi

311.8 psi 235.6 psi

Phase 3 Results

• State Project No. H.011050.6, LA 952

• In-Place Cement Treated Base Course (150 psi goal) -An in-place cement stabilized base course (300 psi

goal) test section will be installed to evaluate cement slurry

Brief Overview of New Spec. Book

• Submit a dust control plan to address weather, sight clearance, operational procedures, traffic control, and any other project specific concerns. Failure to maintain sight clearance will result in the engineer stopping contractor operations.

• The department will identify dust-sensitive areas in the plans. In these specific areas, the dust control plan must also include environmental requirements.

Brief Overview of New Spec. Book

• Section 301 – Class I Base Course

• Section 302 – Class II Base Course

• Section 303 – In-Place Cement Stabilized and Treated Base Courses

• Section 304 – Lime Treatment

• Section 305 – Subgrade Layer

• Section 309* – In-Place Cement Treated Subgrade

*New Section

Implementation

• Plan Change Document

Purpose: Allow the Designer and Planner to Implement Changes to the Construction Contract.

• Specifications

Purpose: Guide the Contractor so that the Provisions and Requirements for the Performance of Prescribed Construction Work are Met.

Implementation

Conclusions

• Special cases (Another tool in the toolbox)

-Urban Areas

-Dust Sensitive Areas (Environmental and Public Concerns)

-Historic Structures

• Not likely cost competitive with dry cement in remote areas

• Contact Information

-Louisiana Transportation Research Center

Gavin Gautreau, P.E. or Khalil Hanifa, E.I.

(225) 767-9110 (225) 767-9127

Questions?