View
36
Download
1
Category
Tags:
Preview:
DESCRIPTION
Construction Sequencing I-15, Ontario, CA . HFL Show Case, June 22, 2010 Peter J. Smith, P.E. The Fort Miller Co., Inc. The Fort Miller Co., Inc. Precast Concrete Company Located in upstate New York Transportation-related precast products for 9 Northeastern States - PowerPoint PPT Presentation
Citation preview
Construction Sequencing
I-15, Ontario, CA
HFL Show Case, June 22, 2010
Peter J. Smith, P.E.
The Fort Miller Co., Inc.
The Fort Miller Co., Inc.
• Precast Concrete Company Located in upstate New York Transportation-related precast products for 9 Northeastern States Specializing in accelerated bridge (and other structures)
construction• Currently exporting precast pavement technology (Super-
Slab®) to other states Provides design assistance to DOT’s Provides forming equipment and training to local precasters Provides specialized grading equipment and on-site training to
contractors and DOT inspectors
• Simple slab-on-grade system
• Standard dowels and tie bars (JRCP)
• Built-in bedding grout distribution (to insure full
and complete support)
• Techniques for precision grading
• Capability of providing 3-dimensional surfaces
The Super-SlabThe Super-Slab®® System System (JPCPS) – Key Features(JPCPS) – Key Features
• Slots on the bottom protects grout from de-Icing chemicals
• Dove tail slots provide resistance to dowel pop-out
Bedding Grout Port
Dowel Grout Port
Dowel Grout
2500 psi before traffic
Dowel and Tie Bar Connection
Bedded (primarily) With Precisely Graded Fine Aggregate Material
SIZE WCS#4 99#8 88
#16 65#30 37#50 15
#100 5#200 1.8FM 2.91
Fine Bedding Material•Fully compacted subgrade
•Acts as cushion on CTB
•Bond breaker between CTB and new slabs
•Provide grade control for new slabs
Installing Bedding Grout
Bedding Insured By Filling Voids (if they exist) With Bedding Grout
FoamGasket
Grout DistributionChannel
•Used only to fill voids•Flow rate : 17 – 20
seconds•600 psi in 12 hours
Proof
Two Types of SlabsSlab shape depends on geometry of pavement surface
Single Plane
Warped Plane
Super-Slab 3D Technology
(x4, y4, z4)
(x1, y1, z1)
(x2, y2, z2)
(x3, y3, z3)
•Develop digital surface model of the pavement
•Extract “x”, “y”, “z” values (from model) for every corner of every slab
•Use values to fabricate slabs in specially designed forms
•Use same values to prepare subgrade surface
What We Are Emulating
Concrete Pavement Fully Concrete Pavement Fully Bedded With Accurate Bedded With Accurate
Surface Surface
Effective Load Transfer Effective Load Transfer Dowels at Joints (to be Dowels at Joints (to be
sawed) sawed) (If you can possibly cast good concrete in (If you can possibly cast good concrete in
place and get a good cure, don’t use precast!) place and get a good cure, don’t use precast!)
Engineering & Design
• Contractor collected field survey data (prior to shop drawing development) Random slab replacement (patches) – widths only of each
hole Continuous installations
• Collected accurate “x”, “y”, “z” data of existing edges to be matched
• Fort Miller developed: Design edge profiles and slab layout drawings Shop drawings (detailed piece drawings)
• Drawings completed months in advance of actual installation To allow time for fabrication
Design Profile Development
New Profile Kept Within Grinding Distance of Existing Edges
Developed Panel Data
Slab Layout Drawing
Panel Fabrication
• Fort Miller partnered with local precaster for slab fabrication• Fort Miller provided:
Specialized forming equipment Training for precaster personnel Continuous check of slab dimensions Periodic check of slab quality
• Precaster: Fabricated, stored and shiped slabs Provided QC and QA Coordinated shipping to contractor
Step by Step Step by Step Installation DetailsInstallation Details(what you will see (what you will see
tonight)tonight)
• Continuous installations must be laid out with total station equipment Must replicate original “x”, “y”, “z” survey Grades for off-set rail must be calculated Leading edges (Panel points) must be
laid out
Step 1 – Lay Out SlabsStep 1 – Lay Out Slabs
Use total station (preferably) to layout
continuous installations (leave marks that will last)
Lay Out Slabs Accurately
Leading edge mark and
panel point grade (cut or fill mark)
Leading Edge
Grade
Grade Shim
Step 2 – Saw CuttingStep 2 – Saw Cutting
Make Full Depth Cuts (don’t try to do it in one
pass!)
Cut in sizes for easy removal
Allow enough room to prevent spalling during
removal
Step 3 – RemovalStep 3 – Removal
Use right size (and enough) trucks!
Slab crab bucket most efficient
(and can be used for removal of existing
CTB)
Super-Grading• The process of grading fully-compacted
bedding material to a surface accuracy of + 3 mm
Requires specialized grading equipment• Using an accurate frame of grade reference • The grade of the adjacent pavement rarely
accurate
Step 4 – Precision (Super) Step 4 – Precision (Super) Grading (Important Key Grading (Important Key Operation)Operation)
• Provides accurate grade control for slabs Set slabs only once
• Provides “nearly complete” subgrade support without grout Slabs can be opened to traffic right away Minimizes volume of bedding grout required
• Allows un-grouted slabs to be used immediately
Benefits of Super-Grading
Milling High Cement Treated Milling High Cement Treated BaseBase
Truck mounted sweeperMilling high CTB
(to allow room for bedding material)
Installing Bedding Installing Bedding MaterialMaterial
Use Skip Loader (Skippy)
(For moving and rough grading)
Bedding Material Storage
Small Scale Grading EquipmentSmall Scale Grading EquipmentRail Supported and Hand Operated
Hand Operated Grader Hand Operated Grader (H.O.G.)(H.O.G.)
Auger H.O.G.
Mini-H.O.G. Shutter ScreedShutter Screed
Setting H.O. G. Setting H.O. G. Rails Rails
Continuous Grading Continuous Grading With H.O.G.With H.O.G.
Three Steps
First Pass (1/4” high)
Last Pass (done)(over 500 LF per night
possible)Compaction
Step 5 Placing Step 5 Placing Slabs(the easy part)Slabs(the easy part)
Slab Sizes
•Thickness – 203 mm
•Width – 3.66 & 3.96 m
•Lengths – 3.66, 4.57, 4.27, 4.57 m
•Weight – 9 Ton (max.)
Prior to Placing SlabsPrior to Placing Slabs
Check with Depth GageTrim with Edge Trimmer (below)
Bond Breaker on Transverse Edge
Shims on Leading Edge Corners
Placement Crane Placement Crane Occupies Un-grouted Occupies Un-grouted
Slabs to Set More SlabsSlabs to Set More Slabs
Keep Outriggers Off Keep Outriggers Off Slabs (if Possible)Slabs (if Possible)
Placing SlabsPlacing Slabs
Placing Slabs To Panel Point Marks
Setting Crew One Man in Each Corner
Setting To Leading Edge Marks
String Line
Step 6 - Dowel GroutingStep 6 - Dowel Grouting
• Dowel Grout is “hot grout” Reaches 2500 psi in two hours
• Keep mixture below 60 degrees Use Ice Water to Control Temp.
• Use Proper Nozzle• Keep Dowel Grout Moving
Do not let it sit in hoses• Wash Out Grout Pump Frequently• 15 minutes per slab
Installing Dowel Grout
Contractor-Designed Joint Dam(clean up dowel grout
immediately)
Fill Dowel Slots and Joints First
(keep it moving)
Bedding Grout
• Mixture of Cement, Water & Admixture Flow rate of 17 - 20 seconds Must flow into thin voids
• Reaches 2 MPa + in 12 hours• Use Proper Nozzle• Keep Holes filled
Installing Bedding GroutInstalling Bedding Grout
Flow Rate of Bedding Grout 17 – 22 Seconds
Pre-bagged Bedding Grout
Proof
Joints
• Treated as construction joints (in CIP) Maximum width < ½”
• As placed joints vary from 0” to ½”
Joints are filled with dowel grout• Bond breaker on one side of joint
Top 2” sawed to uniform ½” width and sealed with silicon sealant
Skewed Joint (Existing)
Transverse Joint
How About Smoothness?How About Smoothness?
• Small differences between slabs are to be expected There are tolerances allowed (by necessity) in
the slabs There are tolerances allowed in the grading
• Super-Slab® specifies finished surfaces + 1/8” May be acceptable for slow speed traffic
• For best International Roughness Index - grind Grinding is a known and accepted practice
Production Rates
• Grading, Placement, Grouting Rates 8 – 10 Slabs (1500 – 2000 SF) per Hour 12’ x 13.5’ (avg.) slabs
• Average rate on this project 39 slabs (in about 6 hours) per shift 526.5 LF. = 6300 – 6800 SF per Shift
• Maximum production rate 52 slabs = 702 LF. = 8424 SF (in one night)
Precast Pavement is
Premium Pavement Under Pressure
A Good Tool For Difficult Locations
Keys to Success(Still More to Learn)
Good engineering Open mindsReal partnering
Recommended