Disturbing as it may be, security is something we now grapple with on a daily basis. Protection from both intruders and blasts has now become part of the planning and design process in many infrastructure projects, from buildings to bridges and beyond.
Ultra-High Performance Concrete (UHPC) has been shown to add a significant layer of security to projects where blast potential or physical intrusions pose a threat to peace and harmony. Numerous studies over the past few years have clearly demonstrated the increased security afforded by this innovative concrete material.
Learn more about what makes UHPC a blast-proof concrete and dig deeper into the tests that back this up.
What makes UHPC a blast-resistant concrete
There are many characteristics of UHPC that make it superior to traditional concrete. When it comes to blast resistance and security, the following attributes make UHPC valuable to infrastructure projects:
Compressive strength—Compressive strength measures the ability of concrete to withstand loads that would result in a decrease in the size of the concrete. While regular concrete has a compressive strength of around 4,000 pounds per square inch (psi), UHPC can often reach 30,000 psi or higher once fully cured.
Tensile strength—Tensile strength is the ability of concrete to resist breaking or cracking under tension. UHPC has a tensile strength of roughly 1,700 psi, as compared to 70 to 300 psi for regular concrete.
Ductility—Unlike regular concrete, UHPC can be stretched out into thinner sections under tensile stress.
Impact resistance—UHPC can absorb three times greater energy than regular concrete. Under impact loading, UHPC has been shown to be twice as strong as regular concrete and dispersed up to four times as much energy.
Concrete proof that UHPC increases security and blast protection
Blast performance of UHPC concrete beams
This study tested 21 beam specimens, looking at the effect of the type of concrete used, steel reinforcement, and other factors. Beams made from different combinations of concrete and steel reinforcements were subjected to blast shocks until failure.
The results proved that beams made from UHPC can resist greater blast loads than those made from traditional concrete. Additionally, when UHPC is combined with high-strength reinforcement, the blast resistance is even greater.
Blast behavior of one-way panel components made of UHPC
In this experiment, three one-way slabs were tested for blast resistance and damage tolerance. Two of the beams were made of UHPC, while the third was made of traditional concrete.
The tests demonstrated that using UHPC in slabs improves blast resistance. It also increases the ability to resist damage, exhibiting less tensile cracking and secondary fragmentation. This study also confirmed that high-strength steel reinforcements further improve blast mitigation.
Use of Ultra-High Performance Concrete to mitigate the impact and explosive threats
This study looked at the performance of UHPC under a close-range blast, testing materials with different fiber contents. The results showed that increasing fiber content improves blast resistance. The UHPC also displayed minimal fragmentation as opposed to traditional concrete, displaying yet another benefit in a blast situation.
UHPC for blast and ballistic protection
This study focuses on the application of UHPC for the construction of larger structures and objects used in security situations, such as protective walls and bunkers. Researchers examined different UHPC compositions, including the type and amount of fiber reinforcements used.
Explosion field tests were conducted. Results showed that UHPC with a greater flexural strength proved to have greater explosive resistance. UHPC containing a combination of fine-grained aggregates and steel fibers further improved blast resistance.
Effect of design parameters on the blast response of UHPC columns
Eight columns (some made with traditional concrete and some made with UHPC) were tested with simulated blast loading. In addition to a concrete type, the study also looked at additional qualities, such as fiber properties, fiber content, transverse reinforcement, and strength.
Columns made with UHPC were more resistant to damage and showed less displacement when subjected to blasts. The use of UHPC has the ability to eliminate secondary blast fragments, further enhancing human safety. Blast resistance improved, even more, when the fiber content of the UHPC was increased from two to four percent.
Repeated penetration and different depth explosion of UHPC
Testers looked at the impact of 14.5 mm bullets and TNT explosives on UHPC samples. The TNT was embedded within the samples at different depths to determine the effect it would have on the damage.
The results showed that steel fibers and basalt coarse aggregates within the UHPC composition improved penetration resistance, proving that the specific composition of the UHPC is important when it comes to blast mitigation.
Cor-Tuf UHPC: Superior blast-proof concrete
As the studies show, the composition of UHPC does directly correlate to the level of blast resistance and protection provided. Contractors, builders, and engineers, when designing and building for security purposes, must be sure to use a UHPC product that offers maximum protection.
Cor-Tuf UHPC is a proprietary mix of UHPC developed by the U.S. Army Corps of Engineers. It was developed specifically to fill a need for a stronger and more resilient material to protect personnel and weapons facilities from blasts and intrusions without breaking the bank.
Cor-Tuf UHPC has a compressive strength ranging from 28,000 psi to more than 116,000 psi. It has a tensile strength of 2,700 psi, (1,000 psi greater than the UHPC average).
Perhaps most importantly, Cor-Tuf UHPC can be engineered into a unique mix design to meet the needs of any security project. Increases in strength come from the proprietary combination of integrated fibers worked into the mix.
A variety of fibers can be used to achieve desired strength delivering maximum blast protection. Cor-Tuf UHPC separates itself from other UHPC products in this space by honing and refining the proprietary constituents which make up roughly 20 percent of its total composition (including fiber). Strict quality control procedures ensure you get the exact mix needed.
Cor-Tuf provides a combination of high strength and superior energy-absorbing capacity against blast and ballistic penetration. The characteristics of this material make it suitable for a number of security and safety-related uses, including:
- Protection from debris impact from tornadoes and hurricanes
- Thin concrete armor panels for vehicles and fixed structures
- Inexpensive ballistic armor
- Blast-resistant panels
- Fragmenting munitions protection
- Forced entry-resistant structural elements
- Bank vaults
- Armored protective enclosures
We are currently working with several military and government entities on protective devices to make buildings and other structures more secure. We are excited to be able to provide increased security and blast protection with Cor-Tuf UHPC, and we look forward to continuing our work to make our nation safer.