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Concrete Mixture Designs for O’Hare Modernization Plan Chicago O’Hare January 12, 2006 University of Illinois (Urbana-Champaign) Department of Civil and Environmental Engineering

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Project Goal Investigate cost-effective concrete properties and pavement design features required to achieve long- term rigid pavement performance at Chicago O’Hare International.

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Project Team Principal Investigators Prof. Jeff Roesler Prof. David Lange Students Cristian Gaedicke Sal Villalobos Zach Grasley Rob Rodden

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Project Objectives Develop concrete material constituents and proportions for airfield concrete mixes Strength volume stability fracture properties Develop / improve models to predict concrete material behavior Crack width and shrinkage Evaluate material properties and structural design interactions joint type & joint spacing (curling and load transfer) Saw-cut timing

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Project Objectives Concrete properties Long-term perfor- mance at ORD Material constituents and mix design Analysis of existing concrete mix designs Laboratory tests Optimal joint types and spacing. Modeling Test for material properties

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FY2005 Accomplishments Tech Notes (TN) - TN2: PCC Mix Design TN3: Fiber Reinforced Concrete for Airfield Rigid Pavements TN4: Feasibility of Shrinkage Reducing Admixtures for Concrete Runway Pavements TN11: Measurement of Water Content in Fresh Concrete Using the Microwave Method TN12: Guiding Principles for the Optimization of the OMP PCC Mix Design TN15: Evaluation, testing and comparison between crushed manufactured sand and natural sand TN16: Concrete Mix Design Specification Evaluation TN17: PCC Mix Design Phase 1

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TN2: PCC Mix Design

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Survey of Existing Mixes

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Tech Note 3 Fiber Reinforced Concrete for Airfield Rigid Pavements Final cost: reduction of 6% to an increase of 11%

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Tech Note 4 Feasibility of Shrinkage Reducing Admixtures for Concrete Runway Pavements Reduced Shrinkage and Cracking Potential ~ 50% reduction Cost limitations (?) Figure 1. Unrestrained shrinkage of mortar bars, w/c = 0.5 (Brooks et al. 2000)

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Tech Note 11 Measurement of Water Content in Fresh Concrete Using the Microwave Method Strengths: quick, simple, and inexpensive Limitations: need accurate information on cement content aggregate moisture and absorption capacity

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TN 12: Guiding Principles for the Optimization of the OMP PCC Mix Design 1 st order: Strength, workability 2 nd Order: Shrinkage, fracture properties LTE & strength gain

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Tech Note 15 Evaluation, testing and comparison between crushed manufactured sand and natural sand Gradation physical properties

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Manufactured vs Natural Sand Visual evaluation Material retained in the #8 sieve shows difference in the particle shape The Manufactured sand shows a rough surface and sharp edges due to the crushing action to which it was subjected. 4mm 500 m Sieve No. 50Sieve No. 8

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Tech Note 16 Concrete Mix Design Specification Evaluation Preliminary P-501 evaluation Strength, shrinkage, and material constituent contents

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2005 Accomplishments Specification Assistance On-site meetings at OMP headquarters Brown bag seminars Continued specification assistance (2006): Material constituents (aggregate type and size, SCM, etc.) Modulus of rupture and fracture properties of concrete Shrinkage (cement content, w/c ratio limits,etc.) Saw-cut timing, spacing and depth Pavement design

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PCC Mix Evaluation – Phase II Effect of aggregate size (0.75” vs. 1.5”) Effect of 1.5” coarse aggregate: Total cementitious content: 688 lb/yd 3, 571 lb/yd 3, 555 lb/yd 3 and 535 lb/yd 3 Water / cementitious ratio: 0.38 versus 0.44 Fly Ash / cementitious ratio: 14.5% versus 0% Effect of coarse aggregate cleaniness

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PCC Mix Evaluation – Phase II Testing Fresh concrete properties Slump, Air Content, Unit Weight Mechanical Testing Compressive strength (f c ) at 7 and 28 days Modulus of Elasticity (E) at 7 and 28 days Split tensile strength (f sp ) at 7 and 28 days Modulus of Rupture (MOR) at 7 and 28 days Volume Stability Testing Drying and Autogenous Shrinkage trends for 28+ days Fracture tests Early-ages (<48 hrs) Mature age (28 days)

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Mixture design nomenclature 9 mixes were prepared: – st – – st AAA.BB ** Cementitious content (17%FA) lbs/cy w/cm **max aggregate size st = 0.75” Otherwise 1.5”

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Phase II Mix Design Results

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Strength Summary

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Shrinkage Results Phase II Total and Autogenous shrinkage

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Drying Shrinkage – Phase II

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Fracture Energy – Phase II G F = cracking resistance of material G F = joint surface roughness indicator Peak Load G F = Area under the Curve Cracking Area

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WST Test 30mm 57mm 2mm Notch detail 200 mm 205mm 200 mm 80mm 40mm 80mm The WST Specimen a b = a/b t

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Testing Plan – 4 Mixtures Wedge splitting specimens (7) 6, 8, 10, 12 and 24 hours 7 and 28 days Cylinders for compression and split tensile strength for 1,7 and 28 days and E values for 7 and 28 days MOR for 28 days

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Fracture Plots of PCC mixtures

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Fracture Energy Results-Phase II Age = 28-days

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Concrete Brittleness Characteristic Length Less brittle mixes w/ larger MSA

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Fracture Energy Shear Stiffness Joint Performance *need crack width! G F vs Joint Performance Chupanit & Roesler (2005)

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PCC Mix Design – Phase II Summary* Larger aggregates reduce strength by 20% 28-day G F similar similar cracking resistance Larger aggregates reduce concrete brittleness 1-day fracture energy with larger MSA greater joint stiffness / performance No significant shrinkage difference TNXX – February 2006 *Roesler, J., Gaedicke, C., Lange, Villalobos, S., Rodden, R., and Grasley, Z. (2006), “Mechanical Properties of Concrete Pavement Mixtures with Larger Size Coarse Aggregate,” accepted for publication in ASCE 2006 Airfield and Highway Pavement Conference, Atlanta, GA.

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Saw-cut timing and depth Stress analysis of slab (temp & shrink) Size Effect (fracture) Model Concrete Material Fracture Parameters Wedge Splitting early ages No method to obtain Critical Stress Intensity Factor (K IC ) and Critical Crack Tip Opening Displacement (CTOC C ) for WST FEM MODEL FOR THE WST SPECIMEN

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200 mm 205mm 200 mm 80mm 40mm 80mm Saw-cut timing and depth Fracture Parameters WST specimen 30mm 57mm 2mm Notch detail a b = a/b t

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Saw-cut timing and depth FEM Model Special Mesh around crack tip Q8 elements Symmetry and BC consi- derations 200 mm 100 mm

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Saw-cut timing and depth FEM Model Stress around crack tip Calculation of K I Quarter point nodes

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FEM ANALISYS P smax = peak splitting load K IC = critical SIF CTOD c = critical CTOD CMOD c = critical CMOD f 1 ( ) = geometrical factor 1 f 2 ( ) = geometrical factor 2 f 3 ( ) = geometrical factor 3 E = modulus of elasticity G f = initial fracture energy FEM MODELING OF THE WST

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Evolution of G F vs Age 1.5” max aggregate size Large increase in G F between 8 and 24 hrs (saw-cutting operations).

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Saw-Cut Timing Model Concrete E and fracture properties(c f,K IC ) at early ages. Using Bazant’s Size Effect Model to analyze finite size slabs. Develop curves of nominal strength vs notch depth for timing. After Soares (1997)

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Joint Type Analysis How can we rationally choose dowel vs. aggregate interlock joint type & joint spacing? Need to predict crack width & LTE Shrinkage, zero-stress temperature, creep Aggregate size and type (G F ) Slab length & base friction

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Reduced aggregate interlock with small max. size CA Crack width, w Dowels deemed necessary

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Larger max. size CA Larger aggregate top size increases aggregate interlock and improves load transfer Crack width, w

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Crack Width Model Approach Step 1: Predict crack opening, w Step 2: Predict differential deflection, δ diff Step 3: Determine LTE Inputs: RH, T, L, E, , C Inputs: w, CA topsize, Step 4: Acceptable LTE? Inputs: δ free, δ diff, Inputs: FAA recommendation Base friction Curling (thermal and moisture) Steel reinforcement Crack spacing Drying shrinkage Temperature drop Restraints *after DG2002

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Step 1: Predicting crack width opening, w Average increase with age due to shrinkage

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Future Joint Analysis Questions What is an acceptable LTE? What is LTE when dowels are removed? Can joint spacing be increase from to 25 ft? How much can LTE be changed by concrete property changes?

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Literature Review Survey of existing mix designs Review of mix design strategies Volume Stability Tests Drying and Autogenous shrinkage Optimization of concrete mixes to reduce volumetric changes Strength Testing Modulus of rupture, splitting and compressive strength Fracture energy and fracture surface roughness Project Tasks and Progress Done, TN2, 3, 4, 15 Done, TN 12 Done Done, TN 12 and TN 17. Done, TN 12, TN 17, conf. paper Fracture Tests Done Status

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Project Tasks and Progress Joint Type Design Slab size and jointing plans: productivity, cost, performance. Optimization of concrete aggregate interlock to ensure shear transfer. Joint (crack) width prediction model for concrete materials. In progress, TN 3. Analysis pending, fracture and shrinkage tests done. In progress, TN 12. Fracture tests In progress

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Project Tasks and Progress Saw-cut timing and depth Saw-cut timing criteria for the expected materials Analytical model / Validation Fiber Reinforced Concrete Materials Overview of structural fibers for rigid pavement Literature Review done, TN 3. FEM model developed to obtain fracture results from WST samples, currently applying results to determine saw-cut timing and depth.

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New Work for FY2006 Functionally-layered concrete pavements Multi-functional rigid pavement Cost saving GREEN-CRETE Recycled concrete aggregate Effect of recycled aggregate on mechanical and volumetric properties of concrete

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Current work: Recycled Concrete as Aggregates (RCA) for new Concrete

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Recycled Concrete Aggregate

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Use of RCA for OMP RCA may lead to cost savings Disposal costs Trucking costs Natural aggregate costs RCA may increase shrinkage? RCA less stiff than natural aggregate RCA can shrink more than natural aggregate Shrinkage may be same or reduced if RCA is presoaked to provide internal curing

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UIUC First Trial RCA from Champaign recycling plant Concrete came from pavements, parking garages, etc. Mix of materials with unknown properties Material washed, dried, and sieved to match natural fine aggregate Soaked for 24 hrs, surface dried, and then 100% replacement of natural fine aggregate

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Saturated RCA vs Lab Aggregates Similar autogenous shrinkage curves

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RCA Summary to Date Optimization of RCA gradation may lead to reduction in overall shrinkage Other concerns: Reduced concrete strength and modulus Potential for ASR from RCA? Source of chlorides to cause corrosion of dowels? Future work - use RCA with known properties Try different gradations Measure strength/fracture properties also

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Functionally Layered Concrete Pavement T, RH P E(z), υ(z), α(z), k(z), ρ(z), D(z) h z Wear Resistant Shrinkage Resistant Fatigue Resistant Support Layers Functions Shrinkage Resistant Layer Support Layers No fibers f B = 0.1% f A = 0.25% f A = 0.5% h 1, E 1, υ 1, α 1, k 1, ρ 1, D 1 h 2, E 2, υ 2, α 2, k 2, ρ 2, D 2 h 3, E 3, υ 3, α 3, k 3, ρ 3, D 3 h 4, E 4, υ 4, α 4, k 4, ρ 4, D 4 Porous Concrete Friction/Noise Layer Fatigue Resistant Layers

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Functionally Layered Concrete Pavement Experimental Program: P h CMOD Bottom layer Top layer aoao h1h1 h2h2 (a) (b) Bottom layer Top layer

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Functionally Layered Concrete Pavement Structural Synthetic Fibers in Beams P h CMOD Bottom layer Top layer aoao h1h1 h2h2

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Functionally Layered Concrete Pavement Steel Fibers in Beams P h CMOD Bottom layer Top layer aoao h1h1 h2h2

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Functionally Layered Concrete Pavement Synthetic Fibers in WST Specimen

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Project Tasks and Progress Recycled Concrete Aggregate (RCA) Review of previous experiences with RCA Experimental program, and test to determine effect of RCA on relevant mix properties In progress

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Project Tasks and Progress Functionally Layered Concrete Pavement Overview of structural fibers for rigid pavement Layered pavement systems- preliminary study Fracture resistance of two layer concrete pavement systems Literature Review done, TN 3. Done, preliminary results show potential In progress

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2006 First Quarter Deliverables TN - Phase II concrete mix evaluation Large aggregate mixtures paper (ASCE) TN – Fracture Properties of Concrete Mixtures (WST)

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Saw-cut timing and depth FEM Model Determination of Fracture parameters

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Saw-cut timing and depth FEM Model Determination of Fracture parameters

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Recycled Concrete Aggregate Some findings from literature When used with a very low w/cm, RCAC compressive strength can exceed 9000psi at 28 d Autogenous shrinkage can be lowered by 60% by adding saturated RCA While there are no reports in the literature, it is likely that RCA increases tensile creep, which would reduce propensity for shrinkage cracking or curling I. Maruyama, R. Sato, “A trial of reducing autogenous shrinkage by recycled aggregate”, in Proceedings of self-desiccation and its importance in concrete technology, Gaithersburg, MD, June 2005.

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