Comparing Building Materials: Facts You Should Know

The world’s most common building material has been around a long time for good reason.

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.

Visit CRSI’s Safe and Sound: Steel Reinforced Construction page focusing on sustainability and resiliency.

Glass Fiber Reinforced Polymer (GFRP)

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.

The cold hard facts:

The research:

Assessment of GFRP properties: A Literature Review and accompanying Executive Summary, by David Trejo, PhD
Technical Review Comments on Durability of GFRP Bars Extracted from Bridges with 15 to 20 Years of Service, by Donald F. Meinheit, PhD

Cross Laminated Timber (CLT)

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.

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 sustainable 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.

More information can be found in the CRSI Technical Note, Cost Comparison of Cross Laminated Timber (CLT) and Cast-in-place Reinforced Concrete Structures.

Steel Reinforced Concrete (SRC) Shear Walls

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.

Reinforced concrete takes on many forms and accomplishes many things — reasons for its longevity. Most importantly, a sound structure that provides comfort and security.