Recycled Concrete
Aggregates
ET 494-SPRING 2014
INSTRUCTOR: CRIS KOUTSOUGERAS
ADVISOR: MOHAMED ZEIDAN
BY: CHASE CHARRIER AND GARRET T TREGRE
Project Overview
Typical Concrete Mixes consist of:




Typical Coarse Aggregate
Coarse Aggregate (gravel)
Fine Aggregate (sand)
Water
Cement
Comparing RCA to Typical Aggregate
 Performance Analysis for three mixes:
 Typical Concrete Mix
 RCA Mix with unknown source
 RCA Mix with known source
 Cost Analysis
RCA
Introduction
Concrete industry projected to be a $100 billion dollar industry by 2015
16 Billion tons of concrete produced yearly
2-3 Billion tons of concrete waste produced yearly
Disadvantages of Concrete:
 Limited space in landfills caused by concrete waste
 Environmental impact on natural aggregate resources
Advantages of RCA:
 Solve landfill problems
 Help save natural aggregate resources
Purpose
Research and test the effectiveness of RCA’s use in the construction field
 Increase RCA’s use in the construction field
 Provided an ECO friendly industry through RCA’s
Design and Proportioning
 Target Concrete Strength of 5000 psi
Target workability 3”-5”
 W/CM Ratio
Durable for sidewalks and pavements
Design Mix – Testing Results
Final proportions
Proportions for Standard Mix: 1
YD3
Proportions for RCA - Unknown Mix: 1
YD3
Proportions for RCA - Known Mix: 1
YD3
Material
Lbs
Material
Lbs
Material
Lbs
Coarse Aggregate
70.34
Coarse Aggregate
69.95
Coarse Aggregate
72.02
Fine Aggregate
53.92
Fine Aggregate
53.92
Fine Aggregate
53.92
Water
10.60
Water
15.20
Water
13.15
Cement
21.85
Cement
21.85
Cement
21.85
Moisture Content Test
 Purpose is to determine the amount of moisture residing inside the aggregates
 Moisture Content Test helps to insure an accurate concrete mix and desired characteristics
 Oven Temperature: 110 – 115 degrees F
 A. Weight of empty Container
 B. Weight of Container + Wet Sample
 C. Weight of Container + Dry Sample (after fixed reading)
 M.C. = (B – C / C – A) * 100%
Trial Mixes
Slump Test
 ASTM C143 Standard
Measures the mixtures fresh concrete properties
 Consistency & Workability- measure of the ease at which the concrete flows
Also measures the consistency between multiple batches of concrete
Different slumps are required for different applications
The slump test measures concrete’s behavior to the force of gravity
 More slump = more water and workability
 Smaller slump = drier mix with less workability
Slump Test Procedure
Fresh concrete is placed into a metal cone with a diameter of 4” at one end and 8” at the other
end being 12” tall
The concrete is placed into the cone in 3 stages and at each stage the concrete is tampered with
a 2’ metal rod, 5/8” in diameter
The final stage is to level off the concrete, remove the cone, and measure the slump
Slump Test
Air Content Test
ASTM C231/C231M-10
Determines the amount of air in a fresh concrete mix
Three Methods:
 Pressure Method
 Volumetric Method
 Free Air Method
Pressure applied to fresh sample of concrete to compress air entrained pores
 Meter on device measures pressure
Pressure-to-Volume relationship to Boyle’s Law is used to calculate air content
Air Content Test
Compression Test
ASTM C39 standard
Measures concrete’s ability to withstand compression forces
Strength normally relates the overall quality of the concrete
Concrete is molded into cylinders in which the length is twice the diameter and the diameter is
three times the maximum aggregate size
After 28 days are given for proper time to cure, the cylinders are tested
Compression test is performed by applying an axial load to the test cylinder at a constant rate
until failure occurs
Compression Test
Compression Test Results
Average Results of Trials
Standard Mix
5483.5 psi
RCA Mix (unknown source)
4361.25 psi
RCA Mix (known source)
4157 psi
6000
5483.5
5000
4361.25
4157
4000
psi
Standard Mix
3000
Unknown Source RCA Mix
Known Source RCA Mix
2000
1000
0
Splitting Tensile Test
ASTM C496 standard
Measures concrete’s ability to resist tensile forces
Tensile strength is much smaller than concrete’s compression strength
Test is performed by placing a concrete cylinder horizontally under a compression machine and
applying a force until splitting occurs
Concrete Cylinder- common size 150mm by 300 mm
Splitting Tensile Test
Splitting Tensile Test Results
Average Results of Trials
Standard Mix
664.01 psi
RCA Mix (unknown source)
512.94 psi
RCA Mix (known source)
443.45 psi
700
664.01
600
512.94
500
443.45
400
psi
Standard Mix
Unknown Source RCA Mix
300
Known Source RCA Mix
200
100
0
1
Abrasion Test
ASTM C779 standard for abrasion testing
Measures of concrete’s ability to last over time
We will measure our concrete’s durability through a sandblasting abrasion test
The concrete abrasion test involves spraying our concrete test piece with a sandblaster from a
distance of 75 +/- 2.5mm for a length of 1 min.
The volume lost due to abrasion is measured by filling the abrasion cavities with modeling clay
Abrasion Test
Durability Test Results
Concrete Mixtures
Abrasion Coefficient Loss
Standard Mix
0.054792449 cm3/cm2
1.818 cm3
RCA Mix (unknown source)
0.076861631 cm3/cm2
2.551 cm3
RCA Mix (known source)
0.07800314 cm3/cm2
2.588 cm3
Avg. Volume Loss
0.09
0.076861631
0.07800314
0.08
0.07
0.054792449
cm^2
0.06
0.05
Standard Mix
Unknown Source RCA Mix
0.04
0.03
0.02
0.01
0
Known Source RCA Mix
Cost Analysis
Proportions for Standard Mix: 1 FT3
Material
Coarse Aggregate
Fine Aggregate
Water
Cement
Avg. Cost Per Ton
Avg. Cost per yd3
$
$13.00
$12.50
$1.12
$110.00
$
$12.34
$9.10
$0.16
$32.45
Lbs
$70.34
$53.92
$10.60
$21.85
$54.05
Average Cost of Standard Concrete
Proportions for RCA Mix: 1 FT3
Material
RCA
Fine Aggregate
Water
Cement
Avg. Cost Per Ton
Avg. Cost per yd3
$
$8.00
$12.50
$1.12
$110.00
$
$7.67
$9.10
$0.21
$32.45
Lbs
$70.98
$53.92
$14.18
$21.85
Average Cost of RCA Concrete
Total Savings Per yd3 of Concrete Using RCA
$49.43
8.5%
Conclusion & Recommendations
 Reduced Compression, Tensile, and Abrasion Strength
 Source of RCA has little affect on overall strength
 More Cost Effective
Recommendations:
 Reduce W/CM ratio for RCA mix to compensate
 Reduce amount of RCA used- 30%, 50%, 75%
Benefits:
 8.5% more cost efficient
 Saving natural resources
 Reduce landfill space
Acknowledgements
Clay Gottschalck, P.E – District 62 Construction Coordinator: Louisiana DOTD Materials Lab
 Lab Testing: Compression and Tensile Test
Trey Tycer – Plant Manager/Owner: Tycer Ready Mix
 Provided Materials: Coarse Aggregate, Fine Aggregate, Cement
Abita Aggregate Recycling
 Provided RCA
References
1. ASTM Standards: C143, C231/C231M-10; C39; C496; C779
2. Gee, King W. “Use of Recycled Concrete Pavement as Aggregate in Hydraulic-Cement Concrete Pavement.” U.S. Department of Federal
ransportation. Federal Highway Administration. 3 July 2007. Fhwa.dot.gov. Web.
3. Kosmatka, Steven H., William C. Panarese, and Beatrix Kerkhoff. "Designing and Proportioning Normal Concrete Mixtures." Design and
Control of Concrete Mixtures. Skokie: Portland Cement Association., 2002. Print.
4. MacDonald, Kevin. "Crushed Concrete." Concrete Construction. Haney Wood, 30 July 2011. Web. 24 Oct. 2013.
5. “Materials: Recycled Aggregates.” Concrete Technology. Portland Cement Association. Cement.org. Web.
6. "Material Testing." Compression Test on Concrete. Building Research Institute, Web. 25 Oct. 2013.
7. Osei, Daniel Y. "Compressive Strength of Concrete Using Recycled Concrete Aggregate as Complete Replacement of Natural
Aggregate." Journal of Engineering, Computers, and Applied Sciences 2.10 (2013): Web. 2 May 2014.
8. Paul, Suvash C., and Gideon V. Zijl. "Mechanical and Durability Properties of Recycled Concrete Aggregate for Normal Strength
Structural Concrete." International Journal of Sustainable Construction Engineering and Technology 4.1 (2013): Web. 3 May 2014
9. "Sustainability Report." Canadian Cement Industry. Cement Association of Canada, 2010. Web. 3 May 2014.
Questions
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