MIT Concrete Sustainability Hub

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

More Information• http://web.mit.edu/cshub/

MIT Concrete Sustainability HubBruce McIntosh, Portland Cement Association