Professional Practice

Using Low-Impact Materials: Sustainable Concrete

Sustainable site materials used in the landscape include recycled-content steel and high fly-ash concrete. ASLA 2016 Professional Residential Design Honor Award. The Rivermark, Sacramento, California / Fletcher Studio.

Concrete is the most widely used building material in the world, thanks to its variety and durability. However, manufacturing cement, the binding material in concrete, is a highly energy and water-intensive process. The sheer volume produced, over 2 billion tons per year globally, is detrimental to the environment. The manufacturing of cement accounts around 7 percent of CO2 emissions globally. Furthermore, supplies of limestone, a core ingredient in cement, are being depleted. Concrete also poses a problem for construction material disposal.

To avoid sending useful materials to the landfill, conserve natural resources, and reduce a project’s carbon footprint, The Sustainable SITES Initiative™ (SITES®) recommends landscape architects specify sustainable concrete from manufacturers using supplementary cementing materials, like fly ash – a byproduct of coal-fired power plants. Landscape architects and designers should reuse concrete from structures on the existing site, like crushed concrete as an aggregate base. Concrete that incorporates recycled materials, like crushed glass or woodchips, are a more sustainable and use less cement than traditional pavers.

With SITES-certified projects growing in application and use, manufacturers are increasingly offering sustainable concrete alternatives, such as permeable concrete material, pavement systems that allow for more water infiltration into the ground, and recycled aggregate material. For example, James Corner Field Operations’ re-design of Navy Pier in Chicago achieved SITES Gold certification in part by working with a manufacturer to develop and implement recycled content in the pavers.

There are a number of ways residential projects can use recycled and sustainably-sourced concrete to achieve SITES certification. SITES recommends designing to minimize impervious surfaces by specifying materials for hard surfaces like permeable concrete, asphalt, and pavers. SITES also recommends an open-grid pavement system, or concrete-grass lattice, as a way to manage urban heat island effect. In addition to recycling on-site concrete and using concrete with recycled material, designers should also consider using concrete that is locally sourced.

There are a number of emerging concrete technologies. For example, “self-maintaining” or “self-healing” concrete like BacillaFilla, which is an engineered microbial glue that is applied with a spray and can repair cracks in concrete, and bendable concrete that is less brittle than traditional concrete and can self-heal with the presence of air and water.

Sources: Concrete Materials and Sustainable Development in the United States, Columbia University 

Organizations 

Cement Sustainability Initiative 

World Business Council for Sustainable Development 

The Sustainable SITES Initiative™ (SITES®) 

EcoSmart Concrete 

U.S. Green Building Council 

Resources 

Permeable Pavers, Paver Search

Sustainable Paving, Montgomery County Planning Commission

A Blueprint for a Climate Friendly Cement Industry, World Wildlife Fund

Tracking Industrial Energy Efficiency and CO2 Emissions, International Energy Agency

Sultan, Washington Pervious Concrete, Concrete Network

Porous Pavement, Milwaukee Metropolitan Sewerage District

Research 

Sustainability of Cement and Concrete Industries, Tarun R. Naik, University of Wisconsin, Milwaukee, 2005

Concrete and Sustainable Development, C. Meyer, Columbia University, 2002

“Making Garden Floors: Stone, Brick, Tile, Concrete, Ornamental Gravel, Recycled Materials & More,” Paige Gilchrist, Lark Books, 2002

“Sustainability Improvements in the Concrete Industry: Use of Recycled Materials for Structural Concrete Production,” Carlo Pellegrino & Flora Faleschini, Springer, 2016

“Green Building with Concrete: Sustainable Design and Construction,” Gajanan M. Sabnis, CRC Press, 2015

“Materials for Sustainable Sites: A Complete Guide to the Evaluation, Selection, and Use of Sustainable Construction Materials,” Meg Calkins, Wiley, 2008

Innovation Resources 

Concrete Minus Carbon, Landscape Architecture Magazine

Making Concrete Green: Reinventing the World’s Most Used Synthetic Material, Guardian Sustainable Business

Five Sustainable Building Materials that could Transform Construction, Smart Cities Dive

The Concrete Conundrum, Chemistry World, 2008

Sustainability in Construction: Using Fly Ash as a Cement Replacement, Phil Seabrook & Kevin Campbell, Peng, EcoSmart Concrete  

New material for urban paving made from 100% waste products, Phys.org

Projects 

The Rivermark, Sacramento, California
Fletcher Studio

Cambridge Permeable Driveway, Cambridge, Massachusetts
Julie Moir Messervy Design Studio

Lee Landscape, Calistoga, California
Blasen Landscape Architecture

High Point, Seattle, Washington
Mithun