mit concrete sustainability hub
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MIT Concrete Sustainability HubBruce McIntosh, Portland Cement Association
Topics• HUB background• Life-cycle assessment of pavement• Life-cycle assessment of buildings
and homes• Econometrics• Green concrete science
MIT Concrete Sustainability Hub• Established by PCA and RMCREF• $10 million investment over next 5
years• Validate and innovate:
– Identify areas in which concrete excels– Identify opportunities for improvements– Create solid technical basis for future
industry development
R&D Platforms• Concrete Science• Building Technology• Econometrics
Concrete Science Platform• Mission: Scientific breakthroughs
toward reducing CO2 footprint of cement and concrete
• Breakthroughs would imply:– Strength with less material– Lower energy processing– Chemical stability
Building Technology Platform
• Mission: Life-cycle assessment (LCA) of concrete buildings and pavements to identify impacts and opportunities
Econometrics• Mission: Assess the impact on jobs
and the economy of sustainable advancements in cement and concrete
Building Technology: Paving• 8 million lane-
miles• 3 trillion vehicle-
miles / year• 27% of U.S. GHG
emissions from road transportation
Improving Paving Performance
• Comprehensive methodology for pavement LCA
• Quantifying greenhouse gases
• Investigate pavement-vehicle interaction
Life-Cycle AnalysisOpportunities from LCA:• “Cradle-to-cradle” analysis• Large impacts beyond initial
manufacturing• Use-phase impacts
Use-Phase Impacts• Fuel consumption• Urban heat islands• Street lighting• Carbonation
Indirect impacts• Traffic delays• Additional materials and energy • Construction equipment emissions• Material waste
Key findings• Whole life LCA needed to capture all
impacts• Use and maintenance phases account
for 33% to 44% of CO2 for interstate highways
Pavement-Vehicle Interaction
• Demonstrates of fuel savings with concrete
• Two factors: stiffness and roughness
Stiffness Roughness
Stiffness or Deflection• Rigid pavements produce less rolling
resistance and better fuel economy
Stiffness
Stiffness or Deflection• Asphalt roads need to be 25% to 60%
thicker to achieve same fuel efficiency as concrete.
• Goal is to assess impacts of pavement properties on fuel consumption for both environmental impact and cost savings.
50-year GHG Emissions
High Volume ArterialC A C A
0
200
400
600
800
1000
1200
1400
1600 PVI (Deflection)Production + M&R
GHG
Emis
sion
s (M
g CO
2e)
Building Technology:Structures
• Life-cycle analysis research for single-family housing, multifamily housing, and commercial structures
Residential Bldgs
Commercial Bldgs
Industry
Transportation
21%
18%
35%
26%
United StatesOther of G7 countriesRest of the world
25%
19%
56%
Why are Buildings Important?
Buildings Life-Cycle Analysis• Examining materials within whole building
context, not just manufacturing and initial construction
• Consider use and operations phases
Single-Family Housing
• Single family homes represent 80% of total residential energy consumption
80%Single family
Multi-family
Single-Family LCA
• Exterior walls
• Wood frame and insulating concrete forms
• Quantity of insulation
• Thermal mass
Key Findings• Concrete homes produce 5% to 8%
lower GHG emissions.
• Concrete homes use 8% to 11% less energy.
• Concrete wall systems have higher embodied energy, but that accounts for only 2% to 12% of GHG over a 60-year service life.
Next Steps: Air Tightness• Not considered in initial study, but
represents greatest potential for additional improvement
• Improvement from average to tight saves 23% of total operating energy
Commercial Buildings• Commercial buildings represent
18% of U.S. energy consumption
Commercial LCA• Compares steel and
concrete structural frames
• Floor to floor heights identical
• 12-story building with 40% glazing
12-
Key Findings• No greater embodied energy than
comparable steel frames• Energy savings when concrete
frame is exposed are 3%; when covered by finishes, 2%.
• Active use of the thermal mass capability of concrete slabs could result in significant savings
Econometrics• Study on life-cycle cost analysis” for
highways, “The Effects of Inflation and Its Volatility on the Choice of Construction Alternatives.”
• Study examines historical data on real prices of construction materials.
Key Findings• Traditional analysis uses the same
escalation rate for concrete and asphalt .
• Assumption of constant real costs can lead to serious cost overruns.
• Study suggests the use of material-specific escalation rates.
Advocacy and Promotion• Working with state and federal
officials to incorporate MIT findings in life-cycle analysis models
• Focus of ad campaign• Goal: Level playing field for concrete
and asphalt.
Ad Campaign
Concrete Science Platform1. Alite/belite
reactivity2. Aluminate reactivity3. Alkali effects4. Water and
dissolved components
5. Mechanical properties of materials
Concrete Science Platform• Industry/MIT collaboration• Significant progress on key topics:
– Alite/belite reactivity– Water and dissolved components– Mechanical properties of materials
MIT Concrete Sustainability HubBruce McIntosh, Portland Cement Association
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