Engineering Green with Concrete

Transcription

1 Engineering Green with Concrete Louisiana Transportation Conference 1/10/11 John T. Kevern, Ph.D., LEED AP 1/19/2011:1

2 Presentation Overview Concrete s Role in Environmental Sustainability How Concrete Pavement Preservation is Sustainable 1/19/2011:2

3 So What Does Green Concrete Look Like? 1/19/2011:3

4 What is Driving This Sustainability Thing? Buildings consume over 40% of United States total energy use, 25% of wood harvested, and 16% of our water Energy expended during pavement construction is equal to travel energy consume on that roadway in one year 1/19/2011:4 Source: US Energy Information Administration

5 Sustainability Mindset We don t inherit the earth from our ancestors but instead borrow it from future generations. Indian proverb Don t break the earth - Don t remove materials faster than the earth can replenish them - Don t pollute faster than the earth can reincorporate and naturally degrade them - Don t do anything to compromise earth s ability to do the previous two 1/19/2011:5

6 Triple Bottom Line Environment Local Social Today Tomorrow Global Economic Regional

7 Sustainability is a Shift in Mindset Command and Control - Focus on smokestack/ tailpipe emissions - Regarded environmental improvement as costly - Encourages adversarial system - Effective for drastic pollution Sustainability - Focus on product lifecycle - Considers societal costs of health impacts - Encourages cooperation and voluntary measures - Effective where control system is in place 1/19/2011:7

8 Concrete Most widely used building material Extremely durable Liquid Stone is versatile 2000 year track record of performance

9 The Life-Cycle of Building Materials Embodied energy for materials acquisition, manufacturing and construction accounts for < 2% of total energy Occupant energy-use accounts for 98% of lifecycle energy

10 Cradle to Cradle Perspective Material Acquisition Manufacturing Construction Operation Reuse/Recycling Life Cycle

11 Material Acquisition Resource Impact Index (Extensiveness, Intensity, Duration, Site Significance) Concrete Aggregate Quarrying Limestone Quarrying Steel Iron Ore Mining 2.25 Wood Boreal Timber Harvesting Coastal Timber Harvesting Source: Natural Resources Canada

12 Energy of Production Aluminum Stainless steel Steel Glass Portland cement Reinforced concrete Timber Bricks Concrete Aggregates Production Energy [GJ/t] Source: Concrete and Sustainable Development, ACI Materials Journal

13 Cement Manufacturing Significant energy Heat materials to % of concrete 33% reduction in CO2 since 1972 Additional 10% reduction by 2020 Limestone additions Saves 11.8 Trillion Btus Eliminates 2.5 million tons of CO2

14 Cement & Recycling In 2001, about 53 million scrap tires (19% of the total about of scrap tires that year) as an alternative fuel source Pound for pound, tires contain 1/3 more energy more energy than coal Recycling tires in this way, effectively removes them from landfills or other disposal methods

15 Concrete Improvements Recycled industrial by-products Fly ash Blast furnace slag Silica fume Recycled wash water Recycled aggregates Landscaping Blocks

16 Recycle Industrial By Products Supplementary Cementitious Materials Fly ash From coal-fired electrical power plants Blast furnace slag From steel manufacturing Silica Fume From silicone manufacturing

17 Concrete Construction Made specifically for each order Little to no waste is generated No shipping carton or wrapping Leftovers used to make landscaping blocks

18 Urban Heat Island Effect Residential zones are 3 warmer Downtown areas are 7 warmer Due to dark-colored roofing and pavement Source: Lawrence B. Livermore National Laboratory

19 Heat Island Effect (Green Highways)

20 Stormwater Management Pervious Concrete 15-30% voids Rainwater percolates through the slab Minimizes runoff to surrounding streams and lakes Functions like retention basins Recharges groundwater supplies

21 Recycled concrete Reusing old concrete Fills and bases Roadways and parking areas Driveways and sidewalks Shoulders, curbs, and gutters Landscaping features Foundations Some Concrete Structures

22 What is Pavement Preservation? A network level, long-term strategy. Focused on extending pavement life and restoring functional condition. Goals accomplished with preventive maintenance, minor rehabilitation, and routine maintenance. 2.22

23 What is Preventive Maintenance? Cost effective treatments applied at the right time. Applied to structurally sound pavements. Maintain or improve functional condition. Does not increase structural capacity (this definition is being looked at carefully and may be redefined in the future). 2.23

24 Traditional Pavement Performance Curves Original Pavement Rehabilitated Pavement Structural/Functional Condition Min. Acceptable Rating Terminal Condition Increase due to Rehabilitation Age or Traffic

25 Rehabilitation Strategies Preventative Maintenance 1 2

26 Concrete Pavements Longevity - hallmark of concrete pavements I-10 east of Los Angeles: Originally constructed in 1946 as part of US Route 66 Ground in 1965 (1 st continuous grinding project in north America) to correct joint spalling and faulting Reground for 3 rd lease on life in 1984 In 1997 the 51 yr old PCCP was ground again Today the concrete is carrying 240,000 vpd A true testament to concrete pavement sustainability!

27 Concrete Pavements! Not just isolated example in California 50 year old pavements common in US Route 23 Minnesota Built 1948 (Ogilvie) JPCP, 9, doweled PSR 4.1 (very good) > 50%, >50yr are >3.1 Note: PSR = Present Serviceability Rating

28 Longevity Less-frequent reconstruction Lower consumption of raw materials Cement, aggregates, steel Lower energy consumption Raw material processing Rehab and reconstruction Congestion

29 Longevity Reduction in pollutants Manufacturing, construction, congestion Lives saved Rigid structure Profile durability Infrequent construction zones All these translate into economic benefits Longevity is a crucial element of sustainability!

30 Pavement Preservation Strategies For an existing pavement, the overall goal is to provide a cost-effective solution that: Addresses pavement deficiencies Satisfies constraints Detailed pavement evaluation required to achieve this goal

31 Key Pavement Evaluation Components Pavement distress and drainage surveys Deflection testing Roughness and surface friction testing Field sampling and testing Which activity is most useful in identifying candidate preservation projects?

32 Pavement Distress Types Transverse Cracking Loading. Long joint spacing. Shallow/late joint sawing. Curling/warping. Loss of support. Settlement/heave. Subbase/edge restraint.

33 Pavement Distress Types Longitudinal Cracking Near centerline: Shallow / late joint sawing. Long joint spacing. Near edge: Loading. Loss of support. Settlement / heave.

34 Pavement Distress Types Faulting A difference in elevation between slabs. Poor load transfer. Loss of support.

35 Pavement Distress Types Map cracking or plastic shrinkage cracking. Construction related. Placement conditions. Improper curing or finishing. Generally a nearsurface defect.

36 Topography and Condition of Ditch

37 Deflection Testing

38 Roughness and Surface Friction Testing

39 Concrete Overlays Thin Concrete Overlays Thick Bonded Resurfacing Group Unbonded Resurfacing Group Bonded Concrete Resurfacing of Concrete Pavements Bonded Concrete Resurfacing of Asphalt Pavements Bonded Concrete Resurfacing of Composite Pavements Unbonded Concrete Resurfacing of Concrete Pavements Unbonded Concrete Resurfacing of Asphalt Pavements Unbonded Concrete Resurfacing of Composite Pavements

40 Develop a Feasible Strategy Strategy: a treatment or a group of treatments needed to address all of the deficiencies on a project. Current In the future.

41 Conventional Rehabilitation Strategies

42 Notes on Life Cycle Cost Analysis The lowest life cycle cost generally represents the most cost-effective strategy. Some aspects of LCCA are controversial (especially user costs). Minor differences in LCCA are not considered significant and other selection criteria may be considered more heavily.

43 Contact Information: John T. Kevern, Ph.D., LEED AP Assistant Professor of Civil Engineering Department of Civil and Mechanical Engineering University of Missouri Kansas City /19/2011:43