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ICSC2015.PRESENTATION
- 1. INTERNATIONAL CONCRETE SUSTAINABILITY CONFERENCE 2015 RECYCLED MATERIAL USED AS AGGREGATE IN CONCRETE MANUFACTURING DAVID HOLT, MICHAEL MULLEN, MATTHEW SNEAD, REID PIERSON, DR. MICHELLE LONDA, DR. JIONG HU
- 2. INTRODUCTION World population – 2.5 billion in 1950 – 9 billion in 2050 – World population is growing at an continuous rate creating a need for more sustainable building practices involving concrete World demand/year – 11.5 billion tons of concrete – 1.5 billion tons of cement – 1 billion tons of water – 9 billion tons of aggregate Conservation of resources – Waste products of one industry can be recycled as a substitute for virgin raw materials of another, reducing the environmental impact of both. – Currently 140 million tons of concrete is being recycled in the U.S. per year. – Sand is being consumed at a far greater rate than its renewal, which necessitates the need to find sustainable alternatives.
- 3. Recycled Products for Coarse Aggregates – Concrete – Glass – Bricks – Ceramics Recycled Products for Fine Aggregates – Pulverized plastic – Sheet glass powder – Crushed granite fine – Fly ash Rubber Tires – 10 billion scrap tires are stockpiled globally – State landfill regulations7 • 38 states ban whole tires from landfills • Leach toxins into the environment • Create harmful fires • Emit significant amounts of CO2 and dioxins when burned as fuel One man’s trash is another man’s treasure! WHY ARE WE HERE
- 4. Static Variables – Portland Cement (13 lbs..) – Pea Gravel (28.2 lbs..) – Water / Cement Ratio (~0.4) Dynamic Variables – Sand • 0.2 wt.% water absorption • Adjusted by % volume – Recycled Rubber Tires • 2.5 wt.% water absorption • Density of rubber crucial • Adjusted by % volume – Super Plasticizer DOE VARIABLES
- 5. Pre cure unit weight (lbs.) Post cure unit weight (lbs.) Slump (in) Compressive Strength (psi) – 9 days – 22 days – 90 days RESPONSES
- 8. TEST MARK COMPRESSIVE STRENGTH No Super Plasticizer With Super Plasticizer
- 9. TINIUS OLSEN STRESS-STRAIN RESULTS
- 10. TINIUS OLSEN STRESS-STRAIN RESULTS The Effect of Rubber Concentration and Super Plasticizer Level on Compressive Strength (90 days cure)
- 11. The Effect of Rubber Concentration and Super Plasticizer Level on Modulus (90 days cure) TINIUS OLSEN STRESS-STRAIN RESULTS
- 12. The Effect of Rubber Concentration on the Compressive Stress / Strain Fracture Behavior of Concrete (90 days cure) TINIUS OLSEN STRESS-STRAIN RESULTS
- 13. ML RubberL Rubber BRITTLE FRACTURE
- 14. DUCTILE FRACTURE MH RubberM Rubber
- 16. ANALYSIS – LEVERAGE PLOTS
- 18. CONCLUSIONS Highlights – Baseline concrete samples reached 9,049 psi – Achieved a 3,000 and 4,000 PSI ultimate strength with one of the rubber formulations – TEST MARK – Toughness enhanced with the addition of rubber – Although the ultimate strength and modulus are decreased, the balance of stiffness and toughness should be valuable in many applications – To be commercially viable, however, an improvement in the interfacial adhesion between the rubber and the cement need to be investigated – With rubber added to the concrete mix the overall weight would significantly reduce fuel cost in transportation. Where do we go from here? – The evaluation of additives to gain back some of the strength lost upon the addition of the recycled tire rubber while maintaining the toughness – Long term durability testing will also be required • Temp Cycle • Thermal Shock • Autoclave
- 19. ACKNOWLEDGEMENTS Texas State Professors – Dr. Michelle Londa – Dr. Jiong Hu – Mr. Jerel Walters – Mr. Steve Zinkgraft Graduate Assistance [Technology] – Eric Adams Undergrad Assistants [Technology] – Brian Ledsinger