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Georgia ACI Chapter Lunch N Learn

Recent research updates from MTSU CIM

Heather Brown

on 1 February 2013

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Transcript of Georgia ACI Chapter Lunch N Learn

Concrete Research Updates MTSU Concrete Industry Management
Dr. Heather J. Brown To Do: What happened to all our concrete? Pervious Concrete Update Image Analysis Durability ASTM Standards and ACI Specifications June 26, 2012 6” diameter cylinder of the top surface of RCC sample
Mark surface with black and white
Sets minimum and maximum contrast

“Planar Image-Based Reconstruction of Pervious Concrete Pore Structure and Permeability Prediction” by Milani S. Sumanasooriya, Dale P. Bentz, and Narayanan Neithalath Sample Preparation June 26, 2012 1. Use ImageJ software
Freeware available at http://rsbweb.nih.gov/ij/
2. Convert image to binary
3. Highlights shaded and pitted areas in black Image manipulation June 26, 2012 June 26, 2012 Surface can look significantly different between RCC mixtures
Sharp changes that produce shadows
Gradual changes in depth of surface are OK
Evaluate mix designs and differences in materials
Speed up mix design develop process for new producer Highlight analysis area (without black and white markers)
Analyze image for black versus white pixels

255 = white, 0 = black
Median / white = 39% black June 26, 2012 Image analysis Key Parameters
Concrete freezes not at 32 degrees F but at 28 degrees F
Number of freeze thaw cycles
Length of time in frozen state
Rate of temperature change Acceptance by Local Agencies Acceptance by Local Agencies City Alley Developer built street Longview, Washington 2008 City Street Sidewalk School Baseball Park Hike and Bike Trails Now Available Artistic Pervious EXAMPLES David Mitchell Raveling Potential (ASTM C 1747)
Cast 3 4”x4” cylinders
LA Abrasion Machine,
500 revolutions
Mass remaining (larger than 1”)

Used to evaluate mixes
The mix with least loss should be most durable
Mixes are performing between 22% - 38% Design Testing Nuclear Density
Similar to ASTM D 2950 (asphalt),
ASTM D 6938 (soils)
Backscatter through plastic
Provides moisture and density Placement Testing Inverted Slump Cone
Fill Inverted Slump
1 lift, strike smooth;
no consolidation

Used for both Paste Drain and Workability
Indicates whether the mix is stable
Will it seal at the base?

Also useful during placement Design Testing Void-Density Curve (ASTM C 1688)

Used to create a Curve to control Quality
Identify target C1688 Density ranges
Very useful during placement Design Testing Fresh Density
(ASTM C 1688)
0.25cuft measure
2 lifts, 20 blows each, proctor hammer

Compare to Void-Density Curve
If outside the range, remedy truck

The PRIMARY means of control during placement Design and
Placement Testing Rex Donahey Tensile and Compressive Strength
4”x8” molds
2 lifts, 10 blows each,
proctor hammer

Standard Curing (same as C 31)
Cure in molds for minimum 5 days

All cylinders capped when tested for compressive

Splitting tensile currently being used Placement Testing To confirm compliance and monitor performance
1. Infiltration (C 1701)
2. Density and Void Content of Hardened Pervious Concrete (C1754-12) Post-Placement Testing David Mitchell Infiltration On-site (ASTM C 1701)
12” ring
1 gallon or 5 gallon, timed

Provides direct measure of water flow
Seen to be somewhat variable across single

Recommending all Contractors perform Post-Placement Testing Maintenance 2008 compared to 2011 C1688/C1688M-12 Standard Test Method for Density and Void Content of Freshly Mixed Pervious Concrete

C1701/C1701M-09 Standard Test Method for Infiltration Rate of In Place Pervious Concrete

C1747/C1747M-11 Standard Test Method for Determining Potential Resistance to Degradation of Pervious Concrete by Impact and Abrasion

C1754/C1754M-12 Standard Test Method for Density and Void Content of Hardened Pervious Concrete

WK29213 New Test Method for Compressive Strength of Pervious Concrete Maintenance Testing THANK YOU!

Questions? No Plastic
Pizza Pan Finishing
Decorative Advances in Pervious Gyratory Compactor Vebe Table
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