settling the dust with environmental compliance cement slurry · settling the dust with...
TRANSCRIPT
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.
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 (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 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
• In-Place Cement Treated Base Course (150 psi goal)
-Project Engineer Initiated Use of Cement Slurry
-Nottoway Plantation (Historic Structure)
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.
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