Sustainability, Materials Engineering and Concrete Cabrillo College ENGR45

Sustainability & Materials Engineering General Statistic - With less than 5% of the world’s population, the U.S. was responsible for about one-third of the world’s total material consumption in Is this Sustainable? Triple Bottom Line! Environment Economy Society

Sustainable Materials Management EPA Workgroup Reports Material Management: focuses on impact of life-cycle stages - “upstream and downstream” vs. Waste Management: focuses mainly on “downstream” RECOMMENDATIONS: Promote efforts to manage materials and products on a life-cycle basis. Accelerate the broad, ongoing public dialogue on life-cycle materials management.

Flow of Materials Where do Materials Engineers “fit” into the production equation? How much decision making “power” do MatEngrs have regarding the life-cycle of a material used in a product?

Question & Answer Sustainable Building Materials What are sustainable building materials? Why would we use sustainable building materials? Answer… Partner up with the student next to you and discuss. Write down a few ideas…

What’s in the Mix? Components of a Basic Concrete Mix Composite Material: Aggregates and “Paste”/Binder Aggregates: course (granite) and fine (sand) Portland cement: mixture of many compounds (silicates+) Water: H 2 O Curing: The importance of Hydration Hydration commences as soon as the cement contacts water. A cement particle grows, spreads and adheres to other growing particles - causing stiffness, hardening and strength development.

Desired Properties of Concrete Strength - Compressive, Shear, Tensile Durability - resistance to freezing and thawing Corrosion - resistance to chemicals Permeability and Watertightness

Fly Ash A Sustainable Building Material? Fly ash: post-industrial waste product from coal-burning power plants. Used as part of “paste” in concrete (est.1970’s) Included in >50% of all US ready mixes (ex. Quickcrete) Added for increased durability of concrete related to corrosion resistance (marine exposure) = enhances life cycle of concrete. Slower rate of strength development (56-day vs 28-day) Cheaper than Portland cement Potential to zero-out carbon emissions created in order to make cement

Question & Answer Fly Ash QUESTIONS If you were… … an Engineer would you specify it? Why or Why not? … a contractor would you use it? Why or why not? … a homeowner or builder would you use it? Why or why not? … a regulator or policy maker, would you mandate it’s use? Why or why not? Answer… Partner up with the student next to you and discuss. Write down a few ideas…

Fly Ash - Revisited A Sustainable Building Material? Fly ash (before use as a binder in concrete) has the potential to leach mercury, cadmium, selenium and arsenic into ground water. EPA is/was proposing two options: (A) place a hazardous waste label on fly ash OR (B) place a non-hazardous waste label on fly ash and let individual states handle the transportation and disposal issues

Question & Answer Fly Ash - Revisited QUESTIONS If you were… … an Engineer would you specify it? Why or Why not? … a contractor would you use it? Why or why not? … a homeowner or builder would you use it? Why or why not? … a regulator or policy maker, would you mandate it’s use? Why or why not? Answer… Partner up with the student next to you and discuss. Write down a few ideas…

Other Examples Other materials with similar issues? Are these materials sustainable? Polymers PBA’s in Nalgene bottles Off-gasing from artificial turf Metal Lead in drinking water valves/taps Lead in cooking pots used to make candy

Concrete Proportioning Let’s get to it…turn to page 272