Concrete vs Asphalt

Concrete vs Asphalt - The Three Environmental Factors   Energy and Emissions: Energy consumption and CO2 emissions during

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 12/5/10 The Three Environmental Factors   Energy and Emissions: Energy consumption and CO2 emissions during production of Asphalt and Portland Cement   SRI: Contribution to the heat Island effect based on the SRI values of Asphalt and Concrete pavements   Recycling: Opportunities for including recycled materials in Asphalt and Concrete mixes, as well as the opportunities of recycling Asphalt and Concrete pavements Energy and Emissions Introduction   Energy consumption is at its peak and with developing countries catching up to the US consumption, significant energy conservation are advised   Similarly, air and water pollution are a serious problem and all industry emissions must be monitored and reduces to possible minimums   CO2 emissions are believed to be the main cause of the green house affect and subsequent global temperature increase Energy and Emissions Values ASPHALT CONCRETE   Petroleum refining is the most energy intensive operation in the US (DOE)   On average, 4 GJ of energy are required to product 1 tonne (1000 kg) of Portland cement clinker   Total amount of VOCs released by refineries per year is 161,207 tons   298,602 tons per year of mono ­nitrogen oxides (NOx)  ­ smog   163,589 tons per year of hazardous air pollutants Energy and Emissions   The production of 1 tonne of Portland cement clinker releases one tonne of CO2.   With 1.5 billion tonnes of cement produced annually it is estimated that the cement industry is responsible for 7% of global CO2 emissions. Energy and Emissions 1 12/5/10 Energy and Emissions Conclusion SRI Introduction   Due to the complexity of Asphalt production, as well as the fact that asphalt is not the main product of petroleum refineries, the portion of energy required to product asphalt is difficult to establish   Horizontal surfaces, pavements and roofs, are major contributors to the heat island effect   About 41% of energy consumed in the US comes from Petroleum   The temperature increase due to heat island effect is estimated between 2 and 8 degrees F, based on the size and surface types of the urban area.   Most of the energy is consumed by process heat generated from refining by ­products   Heat island effect is a phenomena of urban areas, large cities, having increased temperatures over suburban and rural areas   The affects of surfaces on the heat island effect is determined by the standardized measure of SRI   SRI stands for Solar Reflectance index Energy and Emissions SRI SRI Definitions SRI VALUES   SRI is a measure of a material’s ability to reject solar heat, ranges between 0 to 100   It is calculated based on reflectance and emittance   Reflectance (albedo) ranges from 0 (dark/absorbers) to 1 (bright/reflectors).   Emittance is a measure of heat radiation by a surface Asphalt Concrete Material E R Material E R New Asphalt 0.9 0.05 0 SRI New Gray Concrete 0.9 0.35 35 Weathered Asphalt 0.9 0.10 6 Weathered Gray Concrete 0.9 0.20 19 New White Concrete 0.9 0.7 86 Weathered White Concrete 0.9 0.4 45   Example: a standard black surface, placed in full sun, will have a temperature rise of 90 degrees F. The temperature rise for a white surface, under the same conditions, would be around 14.6 dgrees F. SRI SRI SRI 2 12/5/10 SRI Conclusion Recycling opportunities Introduction   SRI is easy to calculate and the benefits of using concrete pavement over asphalt pavement are clear   Recycling is a simple yet effective way to reduce mining of raw materials and to divert waste from landfills CONCRETE Wins! SRI Recycling Recycling opportunities Recycling Opportunities Conclusion Asphalt Concrete   The following materials can be recycled into Asphalt mixes are tire rubber (20lb per 1ton), fly ash, crushed, glass (5 ­15%), asphalt roofing shingles (10%), slag, porcelain, and clay masonry   The following materials are commonly recycled into Portland cement concrete: fly ash (10 ­15%), silica fume, ground granulated blast ­furnice slag (30 ­40%), porcelain, and clay masonry   Concrete pavements can be recycled back into a new pavements using usually about 50% RAP   Concrete pavements can be reused as base for pavement and as aggregate in new concrete Recycling   The recycling processes are similar for asphalt and concrete pavements, because both products consist of aggregates and binders   Unlike concrete, asphalt can be softened and reused as a binder for new asphalt mixes ASPHALT Wins! Recycling 3 12/5/10 Overall Conclusion   Without detailed research and understanding of the oil refining processes, it is difficult to decide which pavement have more imbedded energy   Concrete has much better SRI values and is; therefore, much cooler pavement type   Asphalt has more recycling opportunities 4 ...
View Full Document

This note was uploaded on 05/26/2011 for the course CGN 6505 taught by Professor Mang during the Spring '11 term at University of Florida.

Ask a homework question - tutors are online