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

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 1891 in Bellefontaine, Ohio. Air-entraining agents are added to concrete in the 1930’s. The tallest concrete building is built in 1992. It stands at 65 stories tall. History

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

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

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

Concrete mix

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

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

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

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

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

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

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

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

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

Pre-existing concrete slab

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

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