Sustainable Construction Materials

Overview 

Industrial activity contributes a stress on the carrying capacity of the earth’s resources and sustainable practices for construction have consequently become more important. Asphalt production is one of the most energy consuming industries and Portland cement production and usage are unsustainable. Portland cement has about 1.25 tons of carbon dioxide released per manufactured ton¹ and contributes to large amounts of foreign exchange, which can lead to artificial inflation of cost for developing nations². Utilizing sustainable materials and material production methods can offset the energy need. Among the current and emerging technology for sustainable construction, innovative binders³ to strengthen materials are utilized. In certain agency programs, sustainability in road material use can be based on a variety of factors from noise pollution due to travel on less-maintained roads to the embedded energy costs

Timeline 

• Ancient - Romans, Persians, and Aztec construct stone paved paths to accommodate wheeled vehicles
• 700s - Tar paved roads in Baghdad, Iraq
• 1100s - Street paving becomes more common in western Europe
• 1700s - Modern roads come with the new practice of civil engineering. Portland cement concrete developed.
• 1800s - Pervious pavement first used in Europe
• 1870 - Mordecai Levi laid the first brick street in the United States on Summer Street (between Virginia and Kanawha Streets) in Charleston, West Virginia (completed in 1873). Levi later patented the bricklaying technique in 1889.
• 1916 - The United States Federal Aid Road Act of 1916 is enacted, providing the first federal funding for building and improving roads in the country
• 1974 - Texas and Nevada made efforts to recover and reuse old asphalt paving materials
• 1976-1982 - Federal Highway Administration (FHWA) sponsored more than 40 states to perform and document the use of reclaimed asphalt pavement (RAP)
• 1977 - Edmund Thelen and L. Fielding Howe co-write "Porous Pavement" providing the groundwork for modern application of permeable pavement.
• 2016 - The first photovoltaic road in the world is constructed in Tourouvre, Orne, France.

Materials

Asphalt

• Warm-mixing asphalt has a lower energy need than typical hot-mixing processes - apply this method when possible

Concrete

• Replace Portland Cement with Pozzolans to decrease embedded energy of Portland Cement

Plastics

• New surface material: asphalt based material are being replaced by environmentally-friendly, organic resin-roads such as Eco-Pave.

Recycled Materials

• Use Recycled Materials Components (RMCs), generated from industrial by-products
• Reclaimed asphalt pavements (RAP) consists of reprocessed pavement containing asphalt and aggregates removed during reconstruction, resurfacing, or from accessing buried utilities. It is estimated that approximately 45 million tons of RAP is produced each year in the United States. An estimated of 20 percent of the annual amount of RAP is not recycled and disposed. RAP can be used as an asphalt concrete aggregate, asphalt cement aggregate, granular and stabilized base aggregate, embankment, or fill.
• Recycled concrete aggregate (RCA)
• Coal Combustion Products (CCP’s), generated from coal burning in industrial plants (fly ash, boiler slag...).

Analysis of Implications

Environmental Impacts

• Sustainable materials include recycled asphalt and aggregates, while sustainable production methods can include mixing asphalt at lower temperatures  
• The definition of sustainability differs based on development level, so sustainable practices in one country may be different in another. For example, pozzolana is used in developed nation construction, but is not commonly used in a developing country like Ghana
• Replacement of Portland Cement is a common means of decreasing the embodied energy of a construction project.  
• Locally source materials reduce environmental costs of transport

Durability

• Implement long-lasting/perpetual pavement principles
• RAP generally has no durability concerns when using RAP for embankment/fill materials due to virgin aggregates used in asphalt usually exceeding embankment/fill requirements

Case Studies 

Reclaimed Asphalt Pavements (RAP) Used for Granular Base Construction

• RAP can be used as granular base for paved and unpaved roadways, parking areas, bicycle paths, and other pavement types
• RAP has been used by 13 states (Arizona, Illinois, Louisiana, Maine, Nebraska, New Hampshire, North Dakota, Oregon, Rhode Island, South Dakota, Texas, Virginia, and Wisconsin) as aggregate in base course
• RAP has been used by 4 states (Alaska, New York, Ohio, and Utah) as unbound aggregate in subbase and two states (California and Vermont) have used RAP in stabilized base course
• The use of RAP in embankment construction has been met with generally satisfactory to excellent performance due to the adequate bearing capacity, drainage characteristics, and durability.
• Leaching characteristics of RAP can lead to environmental concerns when there may be groundwater contact

Reclaimed Asphalt Pavements (RAP) Used for Embankment and Fill Construction

• Connecticut, Indiana, Kansas, Montana, New York, and Tennessee have used RAP as an additive in embankment construction.
• California, Connecticut, Illinois, Louisiana, and Tennessee have used RAP directly as the embankment base material
• The use of RAP in embankment construction has been met with generally satisfactory to good performance
• Concerns of using RAP in cases where groundwater contact or runoff quality is measured due to lack of stockpiling and fill placement procedures

Dutch Recycled Plastic Bicycle Path

• Pre-fabricated connecting path sections made from recycled plastic bottles, cups, etc.
• First of its kind in the world, serves as a pilot project to study the effectiveness and feasibility of the concept.
• 3x as durable as asphalt and 70% faster installation
• This principle can be applied to the development of recycled plastic roads

Pavement Management

Tighe & Gransberg evaluated the sustainability practices undertaken by agencies in pavement management. The matrix below shows how each agency evaluated the sustainability of their pavement engineering and management. The most common methods were through proper rehabilitation (virgin material used), pavement life cycle optimization (in-service monitoring/management) and evaluation air quality impacts.

“Players in the Field” 

Ecopave

• Hot In-Place Asphalt Recycling
• Kelowna Airport HIPAR

External Resources 

https://plus.usgbc.org/evolution-usgbc/

https://www.naturalstoneinstitute.org/default/assets/File/consumers/historystoneingreenbuilding.pdf

https://www.worldhighways.com/wh3/wh5/wh6/feature/sustainable-road-construction-current-practices-and-future-concepts

References 

Bediako, Mark & Frimpong, Augustine [December 2013]. “Alternative Binders for Increased Sustainable Construction in Ghana—A Guide for Building Professionals”. Accessed September 11.

Sleep, Matthew & Masley, Morgan [June 2018]. “The Use of Mt. Mazama Volcanic Ash as Natural Pozzolans for Sustainable Soil and Unpaved Road Improvement”. Accessed September 10.

Tighe, Susan & Gransberg, Douglas [January 2013] . “Sustainable Pavement Maintenance and Preservation Practices: Case Study Analysis”. Accessed September 16.