Download - ICSC2015.PRESENTATION
INTERNATIONAL CONCRETE SUSTAINABILITY
CONFERENCE 2015RECYCLED MATERIAL USED AS AGGREGATE IN
CONCRETE MANUFACTURING
DAVID HOLT, MICHAEL MULLEN, MATTHEW SNEAD, REID PIERSON, DR. MICHELLE LONDA, DR. JIONG HU
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.
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
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
Pre cure unit weight (lbs.) Post cure unit weight (lbs.) Slump (in) Compressive Strength (psi)
– 9 days– 22 days– 90 days
RESPONSES
RESULTS-WEIGHT
RESULTS-SLUMP
TEST MARK COMPRESSIVE STRENGTH No Super Plasticizer
With Super Plasticizer
TINIUS OLSEN STRESS-STRAIN RESULTS
TINIUS OLSEN STRESS-STRAIN RESULTS The Effect of Rubber Concentration and Super Plasticizer
Level on Compressive Strength (90 days cure)
The Effect of Rubber Concentration and Super Plasticizer Level on Modulus (90 days cure)
TINIUS OLSEN STRESS-STRAIN RESULTS
The Effect of Rubber Concentration on the Compressive Stress / Strain Fracture Behavior of Concrete (90 days cure)
TINIUS OLSEN STRESS-STRAIN RESULTS
ML RubberL Rubber
BRITTLE FRACTURE
DUCTILE FRACTURE
MH RubberM Rubber
ANALYSIS - MODULUS
ANALYSIS – LEVERAGE PLOTS
ANALYSIS – REGRESSION
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
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