Concrete's many applications
From the foundation of our homes to our skyscrapers, from our community centers to our bridges, transit ways, and all other indispensable infrastructure installations such as dams, offshore oil production platforms, and water treatment plants that are essential to our society’s ability to function efficiently, we rely on concrete every day.
Whether it is structural or architectural precast concrete, or cast-in-place concrete, insulating concrete forms, masonry, concrete pipe, or ready-mixed concrete, we use concrete in so many ways and in so many different types of construction and infrastructure. Each and every one of these applications shares concrete’s fundamental sustainability attributes.
Concrete pavement lasts decades longer than its asphalt equivalent, requires less maintenance and rehabilitation, and, with its strong and rigid surface, makes potholes and ruts virtually non-existent. Recent studies show that concrete pavement is typically not only more cost effective over its lifecycle, it’s also competitive on initial construction costs. The result is cost savings for road owners and less traffic disruption – and frustration - for road users.
From an environmental perspective, the longevity of concrete pavement reduces the need for natural resources like aggregates and energy. Research shows that the construction, maintenance and repair of concrete pavement uses one third the energy required for asphalt pavement. With its rigid surface, concrete pavement also reduces fuel consumption and associated energy emissions. And its light color reduces the “urban heat island effect”, lowers lighting requirements and increases driver safety at night. Concrete pavement means conserved resources, cleaner air, less CO2 emissions.
This makes concrete pavement the responsible choice for our airport runways and bridges; roads and highways; intersections, traffic circles, parking lots (also see pervious concrete) and bus bays.
In addition to research, there are today several tools and resources available to transportation engineers and decision makers to assess and compare the cost and environmental impacts of concrete and asphalt pavement options:
Cast-in-Place and Ready-Mixed Concrete
Cast-in-Place concrete is transported in a plastic state as ready-mixed concrete and deposited in forms on site, with each batch tailor-made according to the specifications of the designer.
It can be used for nearly all types of concrete elements, including foundations, slabs-on-the-ground, walls, beams, columns, floors and roofs. Its onsite, cast-in-place nature makes it an excellent solution for free-forming concrete into a variety of shapes, spans, and forms. Cast-in-place concrete can be post-tensioned, resulting in thinner structural slabs, reduction of material use, and greater flexibility of the interior spaces.
Cast-in-Place concrete has the advantages associated with all concrete such as thermal mass, durability, resilience to disaster, and use of recycled materials. It is always produced in close proximity to its use in building and infrastructure, typically within 60 km of the job site.
Cast-in-Place, ready-mixed concrete is also used for insulating concrete forms, tilt-up concrete, and shotcrete.
Cast Stone and Stone Veneered Precast Panels
Cast stone is a manufactured precast product that gives the appearance of a variety of natural building stones and — when compared to natural limestone — shows many benefits:
- It is easy to customize, which helps limit energy use and waste on site.
- It can contain recycled materials such as supplementary cementitious materials, recycled glass, or other recycled aggregates.
- With care in deconstruction, many cast stone elements can be repurposed and reused.
Applications range from the simplest windowsills to spandrel panels, and to the most complicated architectural elements. Cast stone also helps to mitigate the heat-island effect, typically being manufactured with white Portland cement.
Stone Veneered Precast Panels
Stone veneer-faced precast concrete panels offer many benefits. These include:
- Veneer can be used in thinner sections since anchoring points to precast panel may be placed closer together.
- Multi plane units such as column covers, spandrels with integral soffit and sill sections, deep reveal window frames, inside and outside corners, projections and setbacks, and parapet sections are more economically assembled as veneer units on precast concrete panels.
- Veneered precast concrete panel systems permit faster enclosure, allowing earlier work by other trades and subsequent earlier occupancy, because each large panel incorporates a number of veneer pieces.
- Veneered precast concrete panels can be used to span column-to-column, thereby reducing floor-edge loading and eliminating elaborate temporary scaffolding.
- Smaller stone inserts can be cast as “highlights” in larger precast panels.
Concrete masonry is used in a broad array of applications from residential foundations to commercial structures to hardscape. It has the flexibility of incorporating high quantities of supplementary cementitious material in its mixture. Concrete masonry is typically produced locally, using locally available materials, reducing energy demands and emissions associated with the transportation of raw materials to the manufacturing plant and the finished product to the job site. The thermal mass of concrete masonry significantly influences heat transmission. Masonry systems are adaptable to many uses as they have many design variables, one being the thickness of the wall: a variety of insulation products can easily be attached to the walls, increasing the R-value of the product with a naturally high thermal mass and contributing to the flexibility of the wall thickness. Like other concrete products, concrete masonry is durable, resilient, does not burn, and requires very low maintenance — when properly designed and constructed, concrete masonry is virtually maintenance-free for 100 years or more. The inherent durability of concrete masonry also permits existing construction to be rehabilitated to new uses while reusing much of the original core structure. When a concrete masonry structure has reached the end of its service life, it can be crushed to create rubble and used in other applications.
Interlocking Concrete Pavement
Interlocking Concrete Pavements (ICP) are used in a wide range of applications from pedestrian pavements like residential patios and walkways, municipal sidewalks, plazas, and roof decks, driveways, parking lots, municipal streets, ports and airports. ICP is a cost-effective pavement with a wide range of colors and textures to fit into traditional or modern architecture. ICP provides a human scale and character to residential, commercial, or urban street settings while structurally capable of supporting the heaviest loads.
Also closely related to interlocking concrete pavement are concrete slabs and concrete grids. Use of larger concrete slab paving continues to grow in pedestrian load residential, roof, and municipal plaza and sidewalk applications. Concrete grid pavements can be used to provide a cool, green surface solution for vehicular access lanes, emergency access areas, and overflow parking areas.
Insulating Concrete Forms
Insulating concrete forms (ICFs) are an integrated insulated wall form system where the forms stay in place, providing a continuous thermal and air barrier. Since they are used with cast-in-place concrete, they allow for flexibility in design. They are lightweight and can now be recycled. Like in other concrete applications, insulating forms are durable and last many years. The foam forms stay in place once the concrete is placed, offering a continuous thermal and air barrier and thus providing significant energy savings. Concrete’s thermal mass reduces the effect of temperature spikes outside a building on the temperature inside the building. Concrete walls provide storage of energy with delayed release. The ICF walls provide a contribution from thermal mass to delay temperature spikes for heat or cold that passes through the insulating layer. The resulting lower demand on the heating, ventilating, and air conditioning (HVAC) systems means the size of this equipment can be reduced as well. The exposed concrete walls in this application make it ideal for use in passive solar designs.
Precast and Prestressed Concrete
Precast prestressed concrete systems provide bottom line benefits to the owner, architect, general contractor and structural engineer — and ultimately benefit the end user. A precast system provides an efficient design, cost effectiveness as well as a strong, resilient and durable appearance that will maintain its image throughout a long service life.
There are three typical categories of precast prestressed concrete: architectural, structural, and specialty precast systems. They can be designed as the complete structure wall system, called a “total precast” concrete system, or they can provide just the structure or just the wall system.
Precast concrete is produced by casting plastic concrete in a reusable mold (or "form") which is then moist cured in a controlled environment, stripped from the forms, and ultimately transported to the construction site and lifted (or erected) into place. By producing precast concrete in a controlled environment (typically referred to as the “precast plant”) where temperature and humidity are held constant, the precast concrete is afforded the opportunity to properly cure, or mature, while being closely monitored by plant engineers and quality control personnel.
Utilizing a precast concrete system offers many potential advantages. Since the concrete is plant cast, safety is better controlled than it is with site-cast construction. Precast plants in Canada are certified by CPCI in accordance with CSA standards, assuring quality materials and workmanship at the plant without relying solely on site inspection. Financial and sustainability benefits arise when the forms used in a precast plant are reused hundreds to thousands of times before they have to be replaced, which allows the cost of formwork per unit to be lower than for other types of construction.
The Canadian Precast/Prestressed Concrete Institute (CPCI) has introduced two programs to further foster a culture of sustainability within the industry:
- A CPCI certification program designed to qualify manufacturers who fabricate architectural and structural precast concrete: www.precastcertification.ca
- An optional Sustainable Plant Program designed to improve the environmental impact at the manufacturing level
The Canadian Precast/Prestressed Concrete Institute and its members are committed to being transparent about the environmental performance of precast/prestressed concrete and to helping customers navigate through options so they can make informed fact-based decisions:
Concrete is the predominant solution for culverts and pipes. Concrete pipe, boxes, and manholes are durable and resist rust and fire. Precast products help restore natural hydrology of an area and direct water flow to recharge aquifers. They can be used in stormwater management applications, reducing pollutants and storing runoff in irrigation or retention systems and special designs can help control erosion. Concrete pipe is ideal for use in geothermal systems as it does not release gas into the air and has a high thermal mass, naturally heating and/or cooling the circulating air with the changing seasons.
In tilt-up construction, concrete elements are typically large. The size of the elements contributes to a higher speed of construction and fewer lifting operations. Tilt-up construction offers an ease of modification, reuse, and expansion. Effective continuous insulating designs can be used in tilt-up walls and the large seamless panels have low permeability, minimizing air infiltration and moisture penetration, therefore making it a solution for temperature control. The structural efficiency of tilt-up panels permits the use of large openings and the flexibility of design allows natural daylight to enter buildings effectively and in a controlled manner.
Porous Concrete Pavements
Urban development alters the natural landscape of our communities, creating hardscape surfaces that prevent infiltration of water into soil surfaces and increasing runoff. Stormwater runoff can send as much as 90% of pollutants, such as oil and other hydrocarbon liquids found on the surface of traditional parking lots, directly into rivers and streams. But by capturing rainfall and allowing it to percolate into the ground, soil chemistry and biology can treat the polluted water naturally. Porous concrete pavements offer a low-impact development (LID) solution to restore the natural ability of an urban site to absorb stormwater.
A porous pavement is one with porosity and permeability high enough to allow water to readily pass through and significantly influence hydrology, rooting habitat, and other environmental factors. Porous concrete pavements can be permeable interlocking concrete paving systems (PICP) or pervious concrete pavements (PCP). Permeable interlocking concrete pavement is manufactured in a factory and delivered and assembled onsite. In contrast, pervious concrete pavements are supplied in a plastic state and formed at the project’s location.