Concrete Roads. Environmental aspects Economic aspects Social benefits Other sustainable applications of cement & concrete.

Transcription

1 John Nichols

2 Concrete Roads Environmental aspects Economic aspects Social benefits Other sustainable applications of cement & concrete A4 30 pages

3 Environmental aspects of concrete roads Carbon footprint & Life Cycle assessment (LCA) Impact of the type of pavement on the fuel consumption of heavy vehicles The use of low energy cement C0 2 reduction by burning of industrial wastes C0 2 uptake by concrete Absence of hazardous leaching products Recycling Better reflection of light and reduced heat sink effects in urban ares

4 Economic aspects Life Cycle Cost analysis Climatic and meteorological performance Lighting costs Price stability The significance of competition between the different types of pavement An economic comparison between bituminous and concrete pavements for motorways

5 Social benefits of concrete roads Fewer roadworks mean fewer tailbacks Ride comfort Safety Noise

6 Other sustainable applications of cement and concrete A wide range of solutions in favour of mobility Fire safety in tunnels Soil treatment techniques, insitu recycling and immobilisation of contaminated soils Permeable pavements Air purifying concrete pavement

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8 Definition: Sustainable roads make efficient use of natural resources and respect the environment during their entire life cycle; they improve transport facilities for the entire community, they provide services to society in terms of mobility, safety and comfort by means of judicious choices regarding design, construction, maintenance and demolition

9 Carbon footprint & Life Cycle Assessment Concrete pavements have a favourable impact on LCA Long life savings in raw materials, transport & energy Low maintenance & repair reduction in traffic delays caused by road works

10 CIMBeton LCA study (France) Compared 6 pavements Plain concrete Plain concrete with dowels CRCP Deep lift asphalt with 12 Environmental indicators Odour O 3 smog Toxicity to humans Ecotoxicity Eutrophication (Phos) Acidification (SO 2 ) Greenhouse gases Radioactive waste Wastes Natural resources Water consumption Primary energy

11 Odour O 3 smog Ecotoxicity Toxicity to humans Eutrophication (phospahte ions) Acidification (SO 2 ) Greenhouse gases Radioactive waste Wastes Natural resources Water consumption Primary energy Lifetime (30 yr) impact of road excluding traffic PCP, CRCP, AC

12 Bituminous structure more favourable for: Wastes Greenhouse gases Eutrophication (phosphate) Toxity to humans Concrete structure more favourable for: Energy Water Natural resources Radioactive wastes Acidification Ecotoxicity Smog Odour

13 Lifetime impact of PCP comparing Construction & maintenance with Traffic

14 Impact of the type of pavement on the fuel consumption of heavy vehicles (rolling resistance) National Research Council of Canada four site investigations, different seasons, concrete savings %, average 2.35% TRL (Transport Research Laboratory UK) Laboratory research on the rigidity of pavement and fuel consumption 5.7% reduction in rolling resistance fuel saving of 1.14%

15 The use of low energy cement Fly ash, blast furnace slag & limestone filler Reduce cement demand by 25% Reduce CO 2 by 25% Roads present more scope for use of SCM s

16 Overall CO 2 reduction by energy recovery from industrial waste Tyres, solvents, waste oil, waste water treatment sludge, paint residues used as alternatives fuels in cement kiln significant CO 2 saving over traditional incineration residue disposal saving Methane saving (25 times CO 2 ) Energy saving

17 C0 2 uptake by concrete Concrete absorbs CO 2 during its life: carbonation Cement Manufacture: CaCO 3 + heat = CaO + CO 2 Cement Hydration: CaO + H 2 0 = Ca(OH) 2 Carbonation: Ca(OH) 2 + CO 2 = CaCO 3 + H 2 O

18 C0 2 uptake by concrete Over 40 years: 10 kg CO 2 / m 3 concrete kg CO 2 / m 3 concrete for rubble (2 3 Years) Total: kg CO 2 / m 3 concrete (10-25% of original CO 2

19 Absence of hazardous leaching products Heavy metal contamination of cement by the use of flyash and slag Belgium study, tank test, leachate is harmless

20 Recycling Concrete is 100% recycled, into road base and subbases Austria (also Germany, Poland & Belgium) use twin layers for base Upper course: virgin aggregates Lower course: uses 60% of recycled aggregate as coarse aggregate

21 Better reflection of light and reduced heat sink effects in urban areas Concrete reflects three times more solar energy that asphalt more reflection will slow global warming more reflection in cities will reduce urban heat sink Less energy required for air conditioning

22 Economic aspects Lifetime Maintenance Life Cycle Cost analysis. Climatic and meteorological performance Lighting costs Price stability The significance of competition between the different types of pavement An economic comparison between bituminous and concrete pavements for motorways

23 Climatic and meteorological performance Concrete roads perform better over a range of climatic conditions than asphalt Higher temperatures cause greater rutting in asphalt Wetter conditions cause faster degeneration of asphalt

24 Lighting costs Better reflectance of concrete can be utilised to save on night lighting Canadian study: asphalt 20 lighting columns/ kilometre concrete 14 lighting columns/ kilometre

25 Price stability Price of bitumen tied to oil price volatility Turkey: market situation with high oil price concrete pavements are cheaper first up

26 Significance of competition between the different types of pavement A viable concrete pavement industry gives designers more practical choices More competitive construction market Better buying conditions for the road network owner

27 LCC comparison: Concrete vs AC Belgium Highway Administration Actual road (20 km), cost & traffic over 30 years LCC over 50 year period 4 Concrete & 2 AC pavements

28 Pavement types 4 Concrete CRCP 200 mm Base 60 mm Bituminous Intermediate layer 200 mm Lean Concrete 300 mm Sandstone 2 Asphalt 210 mm & 260 mm AC 200 mm Lean concrete 350 mm & 300 Sandstone 4 different widths 7.2, 8.0, 10.3 & m

29 Total costs, / km motorway (2001), Asphalt Concrete Concrete Asphalt

30 Social benefits of concrete roads Less downtime for maintenance Ride comfort Improved jointing, CRCP, modern equipment Resistance to deformation Safety Skid resistance, aqua planning, visibility Noise

31 Tire/Road Surface Noise Herne, Constructed 1996, Results at 12 years

32 Other sustainable applications of cement & concrete Wide range of options Roundabouts, safety barriers, noise walls Fire safety in tunnels Insitu cement stabilisation Permeable pavements Air purifying concrete pavements TiO 2 catalyst NOx to NO 3 (Nitrates)

33 Conclusion Sustainability: Environment, Economy & Society Choosing a concrete road IS choosing a sustainable solution