Recycled Concrete Aggregates

ET 494-SPRING 2014

INSTRUCTOR: CRIS KOUTSOUGERAS

ADVISOR: MOHAMED ZEIDAN

BY: CHASE CHARRIER AND GARRETT TREGRE

Project OverviewTypical Concrete Mixes consist of:

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

Typical Coarse Aggregate

RCA

IntroductionConcrete 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

PurposeResearch 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 psiTarget workability 3”-5”W/CM Ratio

Durable for sidewalks and pavements

Design Mix – Testing Results

Final proportionsProportions for Standard Mix: 1

YD3Proportions for RCA - Unknown Mix: 1

YD3Proportions 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 ProcedureFresh 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 TestASTM 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 TestASTM 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

0

1000

2000

3000

4000

5000

60005483.5

4361.254157

Standard MixUnknown Source RCA MixKnown Source RCA Mix

psi

Splitting Tensile TestASTM 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

10

100

200

300

400

500

600

700664.01

512.94

443.45

Standard MixUnknown Source RCA MixKnown Source RCA Mix

psi

Abrasion TestASTM 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 ResultsConcrete Mixtures Abrasion Coefficient Loss Avg. Volume LossStandard 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

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.0547924494834245

0.0768616305253594

0.0780031398895974

Standard MixUnknown Source RCA MixKnown Source RCA Mixcm

^2

Cost AnalysisProportions for Standard Mix: 1 FT3 Avg. Cost Per Ton Avg. Cost per yd3

Material Lbs $ $Coarse Aggregate $70.34 $13.00 $12.34

Fine Aggregate $53.92 $12.50 $9.10Water $10.60 $1.12 $0.16

Cement $21.85 $110.00 $32.45

Average Cost of Standard Concrete $54.05

Proportions for RCA Mix: 1 FT3 Avg. Cost Per Ton Avg. Cost per yd3

Material Lbs $ $RCA $70.98 $8.00 $7.67

Fine Aggregate $53.92 $12.50 $9.10Water $14.18 $1.12 $0.21

Cement $21.85 $110.00 $32.45

Average Cost of RCA Concrete $49.43

Total Savings Per yd3 of Concrete Using RCA 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

AcknowledgementsClay 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.

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