In recent decades, a new type of concrete called Ultra High Performance Concrete (UHPC) has been created due to its outstanding strength and endurance. Aside from its many other uses, this high performance concrete may also be applied to the rapid building of bridges and structural repair. The history, composition, and uses of UHPC are all covered in the following paragraphs.
The US Army Corps of Engineers employed UH-PC for the first time in the late 1980s, and it was made accessible in the country in 2000. The Federal Highway Administration (FHWA) was able to launch its inquiry on the use of UH-PC for highway infrastructure because to its commercial availability. The FHWA studies sparked more academic study and demonstration programs. As a result, several articles on UH-PC were produced, as well as a lengthy list of “bridge applications,” which included:
- Prestressed girders
- Precast waffle panels for bridge decks
- Field-cast closure pours for prefabricated bridge elements (Joint-Fills)
- Precast concrete piles
- Seismic retrofits of bridges
- Thin bonded overlays of bridge decks
- Security and blast mitigation applications
In 1997, a pedestrian bridge in Canada was built using UH-PC for the first time in North America. After then, 34 research projects were carried out across several research institutes with the aim of making UH-PC a trustworthy, widely accessible, commercially viable, and frequently used material. Along with Australia, Austria, Croatia, Italy, Japan, Malaysia, the Netherlands, New Zealand, Slovenia, South Korea, and Switzerland, Germany also has a number of bridges that use UH-PC.
Why are all of these countries utilizing UH-PC? It is a material with a projected life duration of 100 years with outstanding strength, durability, flexibility, and longevity.
UHPC has ten times the compressive strength of ordinary concrete. Compressive strength is a material’s capacity to withstand bending under stress (or in compression). The compressive strength of typical bridge concrete ranges from 3,000 to 5,000 psi. The compressive strength of UHPC ranges from 18,000 to 35,000 psi. Tensile strength or tension is another measure of strength. This is the strength of a substance when pulled. Traditional concrete has a tensile strength of 400-700 psi, but UHPC has a tensile strength of over 1400 psi.
While the strength of UHPC is outstanding, its longevity far exceeds expectations. The durability of a substance is determined by how well it works under harsh situations. Durability includes freeze/thaw resistance, chlorine resistance (as in road salts), and abrasion resistance. UHPC possesses hard rock-like characteristics.
Concrete prisms are tested by freezing and thawing while submerged in a water bath. After 600 freeze/thaw cycles, UHPC retained 100% of its material characteristics.
is determined by ponding a 3% sodium chloride solution on the concrete’s surface for 90 days. The degree of chloride ion migration into the concrete is evaluated after 90 days. When tested, UHPC demonstrated extraordinarily minimal chloride migration, with less than 10% of the permeability of regular concrete.
The quantity of concrete abraded off a surface by a spinning cutter in a specific time period is calculated. UHPC has outstanding abrasion resistance, about double that of regular concrete.
– Salt-scaling (loss of residue): < 60 g/m2 (< 0.013 lb/ft3) Abrasion (relative volume loss index): 1.7
– Oxygen permeability: < 10-20 m2 (< 10-19 ft2) Cl – permeability (total load): < 10 C Carbonation depth: < 0.5 mm (< 0.02 in)
The durability of commercially available UHPC was examined independently using six standardized tests, and the findings were published in the Journal of Civil Engineering. These findings suggest that UHPC has significantly improved durability over standard concrete used today, independent of curing procedures:
Cylinder and setup for rapid chloride ion penetrability test. Photo Credit: Journal of Civil Engineering
“The concrete exhibited minimal damage after being subjected to two times the normal number of ASTM C 666 freeze–thaw cycles. It was innocuous to ASTM C 1260 ASR deterioration, to ASTM C 672 scaling deterioration, and to AASHTO T259 chloride penetration. The ASTM C 1202 Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration test result was negligible if any steam-based curing treatment was applied, and was very low otherwise.”
The materials within UHPC fall into three-component premixes: powders, superplasticizer, and organic fibers. The ingredients are:
- Portland cement
- Silica Fume
- Quartz flour
- Fine silica sand
- High-range water reducer
- Steel or organic fibers
What does this combination of components mean?:
Recently published articles, ‘Advances in Civil Engineering Materials’ and ‘Comparison of Conventional and Advanced Concrete Technologies in terms of Construction Efficiency’ both highlight that superior properties of UHPC reveal “distinguishable benefits” like:
- Simplified construction techniques
- Speed of construction
- Improved durability
- Reduced maintenance
- Reduced out-of-service
- Minimum interruption
- Reduced element size and complexity
- Extended usage life
- Improved resiliency
UHPC is a material that is utilized all over the world because its performance above regular concrete is “advanced, accelerated, and enhanced.” WALO and Posillico have collaborated to develop UHPC Solutions. Our objective is to give bridge owners in the United States access to UHPC for bridge-deck overlays, rehabilitation projects, and seismic constructions. We specialize in expedited bridge repair utilizing UHPC to assist in addressing the issue of decaying infrastructure in the United States.