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