1. Recycled Concrete Aggregates
Instructor: Cris Koutsougeras
Advisor: Mohamed Zeidan
Taylor Crumb, Benjamin Moore, Alexander Vena
September 29, 2017

2. Concrete has been in use since 3000 BC when the Egyptians built pyramids.
In 1824, Portland Cement was invented by Joseph Aspdin.
In 1836, the first compressive and tensile tests took place in Germany.
The first concrete street was built in in Bellefontaine, Ohio.
Air-entraining agents are added to concrete in the 1930’s.
The tallest concrete building is built in It stands at 65 stories tall.
History

3. Reducing waste Benefits of using recycled concrete:
With concrete being in existence for over 5,000 years, it is more economic to use recycled concrete rather than virgin concrete.
Benefits of using recycled concrete:
Cost savings
Eco-Friendly
Versatility
Durability
Reducing waste

4. Proposal Test the strength of concrete with known characteristics
Crush and re-use concrete with various added materials
Test strength between cement with RCA and fly-ash with RCA
Reduce transportation costs of crushing old concrete
Reduce carbon footprint

5. deliverables 1 2 3 4 Cost Analysis Performance Benefits of RCA
Alternative Mixes
Different ratios of cement/water, admixtures, fly ash, etc. 3
Performance
Old slab VS RCA slab 4
deliverables

6. Concrete mix

7. Water-to-cement ratio
The water-to-cement (w/c) ratio is a strong factor when determining concretes strength, durability, permeability and wear resistance.
Compressive strength is inversely related to the w/c ratio.
The w/c ratio may affect strength by:
Changes in aggregate size, grading, surface texture, shape, strength and stiffness
Differences in types and sources of cementing materials
Entrained-air content
Presence of admixtures
Length of curing time
Water-to-cement ratio

8. Designing and proportioning concrete
Acceptable workability of the freshly mixed concrete
Durability, strength and uniform appearance of the hardened concrete
Economic
A properly portioned concrete mix should have these qualities:
Intended use of the concrete
Exposure conditions
Size and shape of building elements
Physical properties of the concrete (frost resistance, strength)
When you mix concrete, you should consider these characteristics:
Designing and proportioning concrete

9. Concrete mix testing Moisture Content Slump Air Content
Determine amount of moisture contained within the aggregates
Slump
Measures consistency and workability
The ease at which the concrete flows
Air Content
Determines the amount of air in a concrete mix

10. Tensile Test Measures concretes ability to resist tensile forces
Much smaller than compressive strength

11. Measures concretes ability to withstand compressive forces
Compression
Test
Measures concretes ability to withstand compressive forces

12. Abrasion testing of concrete
Abrasion is the process of scraping or wearing away
Measures concrete’s ability to last over time

13. Abrasion by revolving disks
ASTM C779
Intended to determine variations in surface properties of concrete affected by mixing proportions, finishing and surface treatment.

14. Abrasion by sandblasting
ASTM C779
Mimics rock and dust carried by wind

15. Sandblasting vs. rotating disks
Our first choice is to use the revolving disks.
Due to lack of equipment, we might have to default to sandblasting.
Sandblasting vs. rotating disks

16. Pre-existing concrete slab

17. 40 years old
3 inches thick
Sample piece – 10’ x 10’
West of the Student Union
Mixed at the Sustainability Center at SLU

18. Timeline Time Activity Assigned Person September Research
Alex, Ben, Taylor
Potential Site
Alex and Taylor
October
Exploring test and preparation facilities
Ben
Setting up lab/equipment
Alex, Ben, Taylor (shifts)
Order/prepare materials
Alex
Design Mix
November
Re-check schedule
Pilot testing and trial mixes
Analysis of cost
Taylor
Start preparing test samples