Concrete has been recorded in existence as long ago as 7000 BC. It was used by the ancient Egyptians, and the Romans used it to build the Coliseum and Hadrian's Wall. Throughout history, concrete has proven itself to be a most adaptable and durable construction material.
However, it wasn't until steel reinforced concrete was developed in the mid- to late-1800s that modern engineering possibilities were realized. It quickly became the building material of choice in constructing strong, durable homes, buildings, bridges and roads. In fact, the driving force behind the first reinforced concrete house was a safety concern; the home was particularly designed to be resistant to fires.
Steel reinforced concrete provides reliable protection during disasters, weather-related occurrences, and man-made events. Leveraging the inherent material properties is key to its performance against wind, fire, flooding, earthquakes, and other natural threats, as well as the intrusion of pests, rot, noise and vibrations.
Modern technology has led to remarkably high-performance concrete and high strength reinforcement as well. Buildings and bridges are now engineered to be taller, longer, and more extraordinary than ever before; all while remaining resilient and efficiently constructed. The best building material will enable rather than constrain possibilities.
Reinforced concrete takes on many forms and accomplishes many things — far beyond the structure itself. Most importantly, a safe and sound structure provides comfort and security.
Please click here to read CRSI's statement on the tragic partial collapse of the Champlain Towers South building in Surfside, FL.
Steel reinforced concrete is an attractive building option for many reasons, one of which being its ability to resist damage from harsh weather and natural disasters. As climate change raises the likelihood of extreme weather events such as large storms, building structures from materials specifically engineered to face such challenges becomes increasingly necessary. The benefits of a steel reinforced concrete structures aren't limited just to their durability: concrete structures made with reinforcing steel are adaptable, economical, and sustainable as well.
Buildings, bridges, dams, and other structures made from steel reinforced concrete can withstand hurricanes, tornadoes, earthquakes, and floods.
Steel reinforced concrete won't catch fire or spread toxic smoke and has inherent fire resistance that does not require additional costly treatments.
Steel reinforced concrete research and engineering spans decades and helps support industry innovations to better shape our modern world and future.
Steel reinforced concrete structures can be inexpensively rearranged to new configurations and adapt as new technologies or uses are adopted.
Using reinforced concrete helps to reduce noise from outside and adjacent compartments, be it in an office, apartment, or patient room.
Reinforced concrete typically is cast to precise specifications with little excess, reducing waste and resulting in a greener and more flexible product.
Facing the realities of climate change, members of the construction industry have committed themselves to continuing and improving upon the sustainable development initiatives that have been in place since the early 1990s. When considered across their full lifecycle, steel reinforced concrete buildings are the smart choice for a builder prioritizing sustainability:
Concrete permanently captures carbon in the atmosphere in a process commonly referred to as carbonation, offsetting the emissions of cement manufacturing over the life of the structure. Additionally, concrete mix designs typically incorporate industrial by-products such as blast furnace slag and other materials that would otherwise be considered unusable waste.
The primary raw materials used to make concrete are abundant in most areas of the world and most ready-mixed plants are well within 100 miles of the project site. A reduced shipping distance for local building materials minimizes fuel requirements for transportation and handling, as well as the associated energy and emissions.
Virtually the entire feedstock of rebar is recycled each year, avoiding massive energy expenditures and environmental damage from mining—without rebar recycling, one ton of steel reinforcing bars would otherwise require about 2,500 pounds of ore, 1,400 pounds of coal, and 120 pounds of limestone.
Roughly 117 million metric tons of carbon dioxide are released into the air each year by air conditioners—steel reinforced concrete buildings uses thermal mass to reduce the demand for heating and cooling.
The United States Green Building Council (USGBC) has created a credit-based rating system called Leadership in Energy and Environmental Design (LEED), to evaluate the environmental performance of virtually any building while promoting sustainable design. Projects earn points for environmentally friendly actions taken during the construction phase and beyond.
Buildings constructed of cross laminated timber (CLT) cost significantly more than cast-in-place steel reinforced buildings. A study by a respected structural engineering firm headquartered in the Pacific Northwest found that CLT buildings can cost as much as 30 percent greater than those constructed of steel reinforced concrete. The study also showed that square foot costs of some actual CLT projects are also greater than comparable steel reinforced structures based on national average structure costs. More information can be found in the CRSI Technical Note, Cost Comparison of Cross Laminated Timber (CLT) and Cast-in-place Reinforced Concrete Structures.
A simulated model of different forest practices at 64 sites in western Oregon and western Washington showed that harvesting practices currently favored by forestry firms will likely decrease the overall health and carbon storage when compared to more sustainble but more costly harvesting methods not currently favored by the logging industry. The U.S. Environmental Protection Agency's science advisory board declared that treating wood as carbon neutral was "not scientifically valid"; materials experts state that more sophisticated and comprehensive life-cycle assessments (LCA) are needed to track the biogenic carbon flows in forests when building CLT structures, such as tracking the carbon debt that is incurred when a forest is harvested.
Concrete members with glass fiber reinforced polymer (GFRP) reinforcing bars are more expensive than those with steel reinforcing bars. Not only are GFRP bars more expensive, but recent studies have shown that when designing concrete members of the same size, more reinforcement is required for GFRP than for steel reinforcing bars. Also, GFRP reinforcement exhibits low modulus of elasticity values, low ductility, and lower bar-to-concrete bond compared to steel reinforcement, which can result in structures with larger deflections and larger crack widths. GFRP bars degrade in conditions of moisture in concrete, which can lead to a significant loss in strength over time. Furthermore, unlike steel reinforcement, reliable, repeatable, and accurate methods for assessing the performance of GFRP reinforcement have not been developed, and there is minimal consensus on the long-term performance of GFRP reinforced concrete.
Steel reinforced concrete shear walls have been a safe, efficient, and cost-effective way to resist lateral forces in buildings for many years. These time-tested structural elements have an outstanding performance record when subjected to the effects from wind and earthquakes. When compared with steel plate and mass timber shear walls, steel reinforced concrete shear walls are easier to coordinate with other building systems and do not have long lead times associated with offsite detailing fabrication, shipping, and staging, which allows projects to be started earlier and completed sooner. Also, changes in the location and/or size of openings, embeds, and MEP penetrations can be accommodated relatively easily and with minimal cost compared to other materials. More information can be found in the CRSI Technical Note, Benefits of Steel Reinforced Concrete Shear Walls in Buildings.