UHPC Earthquake security systems for existing buildings

Ultra High Performance Concrete (UHPC) is a high-strength, ductile material formulated by combining cement, microsilica, fine sand, water, and steel or ceramic fibers and mesh.

The UHPC concrete provides compressive strengths up to 250 MPa / 36200 psi and flexural strengths up to 30 MPa / 4300 psi.

The ductile behavior of UHPC is, with the capacity to deform and support flexural and tensile loads, even after initial cracking. 

 

Façade elements made by UHPC, protect people and vehicles in an earthquake against fragments litter in building structures made 
of concrete and brickwork.

Concrete ceilings are rigid and brittle structures that at the an earthquake stress the concrete structure can break partially. The fracture is not 
a slow phenomenon under load - the fracture occurs when overloading on suddenly.

The result is that to loosen individual fragments of the ceiling could (fragments litter) fall on machines or people. Are the fragments large enough, it can lead to complete component failure.

UHPC prefabricated ceiling structures prevent like a prestressed network the fragments become loose during the quake from the ceiling.

People and machines are protected by such a suspended ceiling construction.

Emergency exits can win with such additional structure several times of safety.

Just as concrete ceilings and concrete columns are complex constructions an essential safety feature of a quake. The concrete columns must take tremendous 
flexural and compressive forces. A chipping of the concrete structure of the inner steel reinforcement would have a very rapid component failure result.

Concrete columns can by a jacket (by shedding) of UHPC gain much stability and carrying capacity. A chipping of the concrete structure at a load by an earthquake of small and medium thickness is almost impossible with the appropriate cover. 

Advantages of UHPC

• Extreme high compressive strength
• High flexural strength
• Extreme low porosity
• Extreme good flowability
• Fast increase of compressive strength (min. 70% after 48 hours)
• High wear and impact resistance
• Absolute frost and thaw resistance
• Impermeable to fluids but still vapour permeable
• Anticorrosive features
• Good bonding to sub-bases, aggregates and reinforcement
• High temperature resistant
• Jointless lining
• Usable as mortar, grout and spray
• High ductility in combination with fibres or nano fibres
• Usable with standard concrete tools
  
  

UHPC - His entry before and after a quake

UHPC materials can be used as additional safety in new concrete structures such as buildings, bridges, etc. For existing buildings and very old buildings, targeted activities involving the use of UHPC materials can significantly increase the safety of people and buildings. With UHPC materials, damaged buildings can be repaired to restore their old stability or improve their stability against earthquake loads by improving their building structure.

Possible applications for high quality UHPC materials

Repairing

To make existing structures safer for future earthquake

Retrofitting

To upgrade the earthquake resistance up to a level of  the present day codes by appropriate techniques

Strengthening

To upgrade the seismic resistance of the a damage building

Rehabilitation

Reconstruction or renewal of a damaged building to provide the same level of function, which the building had prior to the damage

Restauration

Rehabilitation of buildings in a certain area

Remoulding

Reconstruction or renewal of any part of an existing building owning to change of usage or occupancy

Example of retrofitting techniques

• Minor cracks
  Repair by injecting UHPC
• Buckled longitudinal reinforcement, broken ties and crushed concrete
  Replacement of new reinforcement welded with existing bars and new additionally closed ties were placed, UHPC concrete with low shrinkage properties installed.
• Severely damaged columns adjacent to added walls
  Retrofitting with encasing in UHPC concrete with appropriate longitudinal and transfers reinforcement.
• Other columns
  Retrofitted with wire mesh and cover with 50 mm UHPC concrete by spraying or casting
• Existing masonry walls
  Are retrofitting by using wire mesh and 30 mm of UHPC® mortar or spray

Like concrete cover constructions, concrete columns are also essential safety aspect in a quake. The supports have enormous bending and compression forces to take. 
A spalling of the concrete structure from the internal steel reinforcement would have a very fast component failure result.

As with the concrete floors, columns can be replaced by a grouting UHPC gain significantly in stability and carrying capacity. A flaking of the concrete construction is under load from a quake of small and medium strength with 
appropriate sheath almost impossible.

In a quake will be in the brickwork of a building very quickly showing cracks in the in the worst case, individual stones break loose (Rubble throw) or a whole bandage, which too can lead to a component failure. The cracks in the masonry after a quake are permanent and can become one uninhabitability and demolition of 
the building to lead.

Damaged masonry will be repaired differently depending on the degree of damage.

Fine cracks can be filled with UHPC injection methods. Loose masonry, bad mortar can be increased by new masonry and UHPC mortar substantially in the strength and bending tensile strength. Masonry can also be improved in its entire surface with a fibre reinforced UHPC layer in combination with steel or fibreglass reinforcement substantially in its static structure. Especially glass fibre or carbon fibre reinforced 
UHPC show a high ductility.

In any case, should structural modifications such as those described here, be agreed in consultation with 
an architect, stress analysts and the competent local planning authority.

UHPC Security projects in south of Europe

Two new UHPC security projects are
scheduled for the coming year. Both
projects are to be carried out in Europe.



The first project is a concept for securing
private property. In a former mine in the
Alps, securing rooms of the highest security

class are to be installed in former tunnels
on different levels of this mine. In order to
maintain this safety class by insurance
companies, investors have specified the
extension of the tunnels and individual
rooms using UHPC concrete.
In the first stage, about 8000 tons are to
beinstalled.



The second project also applies to the
protection of private property. In this
concept, a former military nuclear bunker
is being rebuilt. Again, most of the new
structural alterations are planned with
UHPC.
For both projects, UHPC concrete is just
one part of the backup work. We have
developed a new UHPC material quality
for both projects, which can be optimally
processed in very large quantities in both
very different locations.

UHPC Construction test for the deep sea use

Research in deep sea construction

For more than a year, we participated in a research project of a German university. It was about the exploration of future concrete constructions for the deep sea.

For a few weeks, the result is available. The UHPC Binder material manufactured by us passed the tests by far from other binder materials.
The reasearch team of the university did models made of different concrete materials The models have been tested for corrosion, leaks and pressure resistance. The compressive strength should be so high that the concrete construction can withstand a sea pressure of 3500 m /2.17 mi permanently.

 

At the end of the long-term test, there were no cracks or other damage to the UHPC concrete construction.

 

Research in deep-sea energy storage
Another interesting research project is the construction of compressed air storage balls for the deep sea. The first concrete ball was manufactured in Germany by the Hochtief company and successfully tested as part of a research program. A very good standard concrete quality was used, but it reaches its material limits with a diameter of over 3 m.

One problem that still needs to be solved is the limited transportability of such hollow spheres due to their diameter.
For commercial use, the diameter must be larger. This means that the hollow spheres have to be manufactured on site, which is very costly, or the hollow sphere is manufactured from several prefabricated UHPC concrete elements, similar to the tower elements in wind power plants.

UHPC Offshore grouting could be an interesting alternative solution to this standard concrete here.

Why?

UHPC has a very high compressive strengt of over 200 MPa / 29000 psi
UHPC has been used in the offshore sector for more than 30 years.
UHPC is absolutely resistant to salt water
UHPC is easy to pump and is self-compacting
UHPC constructions can withstand much greate external and internal pressure loads than standard concrete. Due to the enormous compressive strength, the necessary wall thicknesses can be reduce  depending on type of construction
UHPC is waterproof from 10 mm thickness. Steel reinforcement is much more corrosion-proof in UHPC than in concrete
UHPC has an extremely low to no pore volume.
As far as the heat development during pressure build-up is concerned, the standard version of UHPC is temperature resistant up to 450°C. In the high temperature version, UHPC is permanent temperature resistant up to over 1000°C / 1832°F.

A difference in the definition of UHPC is always a difference in quality

The American Federal Highway Administration (FHWA) defines UHPC as follows:

UHPC is a fiber reinforced, portland cement based product. Through the appropriate combination of advantagements in superplasticizers, dry constituent gradiation, fibre reinforcments and supplemental cementitious materials.

UHPC is a cementitious composite material composed of an optimized gradation of granular constituents, a water-to-cementitious materials 
ratio less than 0,20 and a high percentage of discontinuous internal fiber reinforcement.

The mechanical properties of UHPC include  compressive strength greater than 150 MPa and a flexural strength geater than 15 MPa.

We define our UHPC grades as Ultra High Performance Concrete but without steel fiber reinforcement.
For all our UHPC grades, whether cast, mortar or spray, we achieve the technical values without the addition of any fibers.

UHPC is a cementitious composite material composed of an optimized gradation of granular constituents, a water-to-cementitious materials ratio less than 0,20 and no procentage of internal fiber reinforcement.

 

The mechanical properties (without fiber reinforcement) of UHPC include minimum compressive strength of 150 MPa (up to 260 MPa and more) and a minimum tensile strength 15 MPa (up to 30 MPa and more). We achieve 70% of the maximum nominal strengths less than48 hours and not 28 days.

Of course, fibers of all possible qualities and geometries, steel reinforcements and a wide
variety of aggregates can be added to the UHPC concrete. On our website you will find a long list of
these materials that we have been using for over 20 years. But if we want to compare material with
material fairly, we have to compare the base with each other and that means the pure UHPC binder without fibers and reinforcements.

A difference in the definition of UHPC is always a difference in quality.

                     Our HPC and UHPC compressive strength standard

UHPC flooring system for residential housing, parking decks and concrete repair

The UHPC is known in the industry as extreme

wear-resistant flooring for more than 25 years.

Recently, UHPC floor coverings are increasingly

being used in residential housing projects. One

of the many advantages over traditional floor

coverings is that the UHPC floor covering is

absolutely watertight from a layer thickness of

8 mm. UHPC floor coverings can be processed

just like normal cement screed. In  addition to

the above-mentioned waterproofness, UHPC

flooring coverings also have a very high

compressive strength.

UHPC floor coverings are ideal partners for all

kind underfloor heating systems.

The fast strength development, with more than

70% of the nominal strength achieved after 48

hours in the normal quality, makes it an

interesting floor covering for a variety of

applications.

If repairs are carried out in damp basements or

damp existing floors, UHPC flooring can be

installed directly on the damp surface.

UHPC flooring is also an outstandingly extremely

durable corrosion protection for everything that

is cast in this material, such as reinforcements

and for that already a few millimeters cover is

sufficient.

If UHPC concrete is used, expensive electrical

corrosion protection systems or corrosion

protection coatings are unnecessary.

UHPC in alternative and regenerative energy production

UHPC materials are used in all processes of alternative and active native energy production used as the material for foundations, as a lining-material for protection against corrosion, wear and as a construction material. Due to the diverse application possibilities and the superior properties compared to standard concrete qualities, UHPC are increasingly used in the mentioned areas. UHPC has the advantage that it can be processed just like standard concretes.

Hydroelectric power plants or storage power plants
Due to the extreme corrosion resistance of UHPC concrete constructions with a much higher reinforcement density per volume can be used. This can significantly increase the strength of the construction or the wall thicknesses or layer thicknesses can be reduced while maintaining strength.
In the right combination UHPC is very resistant to wear and cavitation.
Since UHPC already reaches 70% of its maximum nominal strength in the standard quality after 48 hours and in the special quality after only 12 hours.
UHPC is available as mortar, casting material and shotcrete material.

Tidal power plants
Some tidal power plant systems are already being used in Europe and Asia. There are now a lot of technical variations of tidal power plants for the coasts but also for directly in the sea. One thing all needs a stable seawater resistant and durable foundation.
Based on the experience gained with the foundation systems of the offshore wind power plants, high quality UHPC materials are ideally suited for this purpose. In particular, the enormous adhesive power of UHPC in anchoring and bolt system is required here. What is once shed in a UHPC foundation can no longer be removed from the foundation, even with enormous forces. Not only in this regard, UHPC is many times superior to normal standard concrete.

Biogas power plant

Biogas has been produced in many small plants in the past. There are already very large production facilities in Europe. The plants have corrosion and wear problems due to the production process. Especially wherever standard concrete was used. Here, a UHPC protective layer of a few millimeters can be used to achieve permanent corrosion protection. To achieve a very long service life, UHPC concrete should be used for the new construction.

UHPC the future competitor of steel in many applications

We know many people think UHPC is just
a concrete, possibly a special concrete and
with this concrete you do what you just do
with concrete, nothing more. People which
think in this way, should not continue to
deal with UHPC in the future and continue
to mix their old beautiful concrete.

The philosophy of hhbc-consulting is not
the simple replacement of concrete with
UHPC. That would be like replacing gravel
with diamonds.

We use UHPC in the construction industry
where it makes sense, in very specific areas
but our real competitor market in the future
is the steel market. There are a huge number
of applications where UHPC is better, more
durable, cheaper, easier and faster to
manufacture than steel.
UHPC is corrosion and wear resistant and in a HT Version also high temperature resistant (up
to more than 1000°C).


One example of many from the past years, Rolling bearing systems
A steel mill suffered damage to several rolling bearings in the area of ​​the rolling line (the area where the hot slabs are rolled at high speed and high speed to thinner plates). These rolling bearings are manufactured from a very special casting. The problem was that not enough bearing systems were available. These bearing systems are extremely expensive and have a very long delivery time.
In this case the steel plant would have had to wait more than 4 months. What would mean 4 months, the rolling mill could only be used to 30% of the capacity, a million loss.

By chance, we had heard of this problem in a
meeting for a machine floor renovation. We
looked at the drawings and specifications out
of pure interest. After a short internal
discussion, we made the following proposal
to the plant management:
We can copy the bearing completely made of UHPC. We could mix the UHPC material with graphite balls of a certain quality and size. We could achieve a high compressive strength of the material. We could process it to have similar surface roughness as the original bearing and what was extremely important we were sure to provide such a bearing to the factory in just four weeks.
We have provided the factory with the bearing systems within four weeks at one sixth of the original price. The bearings were in operation for 5 months, by 80% of the production capacity until they could be replaced with the newly made cast bearings. We have saved a lot of money for the plant with our UHPC solution.
´

UHPC concrete for precast production

UHPC concrete has many commercial as well as technical

advantages over standard concrete for the production of 

precast concrete elements.

More and more architects are specifying UHPC concrete 

as a standard material for their façade design. There are 

no design limits for façade constructions.
In recent years, we have developed UHPC binder systems 

that can be processed into lightweight concretes or 

insulating concretes, especially for façade construction.

- We produce UHPC materials with a strength of

   40 MPa to 240 MPa.
- Our UHPC materials reach 70% of their maximum

   nominal strength within 48 hours. Faster strength

   developments are possible on customer request.
- We only need sand, not gravel, to process UHPC

   concrete.
- With our UHPC Desert Sand Binder, desert sand

   can also be processed without any problems.
- All of our UHPC materials are self-compacting

   and need no or very little vibration.
- Our UHPC materials have extremely little to no pore

   development.
- The nanotechnology development of our UHPC

   binders enables extremely fine surface structures to

   be created.
- With the use of fibre reinforcement it is possible

   to create very thin structures of high strength.

- For prestressed elements, the pre-tensioning force
   of UHPC material can be chosen to be much higher
   due to their very high strength than standard concrete.

- Very good flow properties for casting complicated

   geometry and filigree surface structures.

Processing of UHPC binders
Only a shaft or pan pot mixer is required for

processing.
The UHPC binder is mixed with sand or desert

sand and a very small amount of water.
It is not necessary to add additives.

Applications

• Double walls 
• Pre stressed elements 
• Tubes
• Bridgedeck elements
• Stairs
• Piles
• Supports
• Tunnel segments
  
• Facade elements
  
• Balconies
• Sea defence units
  
• Floor tiles in large geometries                
  
• Security
  
• Vertical garden (facade) elements
• Sewage pipes and box culverts
• Floating elements
  

UHPC - a material for many applications in onshore and offshore wind energy production

UHPC Ultra High Performance Concrete has been used for many years in offshore wind

and onshore wind energy production.

We produce our UHPC for these applications. The new grades UHPC are currently being tested and will be available to the market later this year.

Monopile wind turbine designs are still the most widely used standard foundation design in many coastal areas. Jackets -, Gravity base -, Tripods - and Tri-piles systems are also used depending on requirements and needs.

UHPC grouting is used in all foundation techniques.

Monopiles

UHPC grouting material is used for the connection between monopile and transition pieces.

We estimate that more than 2000 monopiles worldwide have been installed with UHPC grouting and transitions pieces.

At the moment we are working on the 4th generation of grouting material. In addition to the technical improvements, the fulfillment of a wide variety of environmental requirements is the prime objective of the development.

Benefits of using UHPC grouting material for the transition piece

• Extremely high strength
• Very good fatigue properties
• Minimal shrinkage
• Extreme bond between UHPC grouting material and steel
• Fast setting development
• Very high inner cohesion
• No mixing with sea water
• Absolutly seawater resistant
• Very low hydration heat
• No corrosion

Tripile

A Tripile foundation consists of three steel piles driven into the seabed after which a three-legged transition piece structure is slid into the three piles. The overlaps between piles and transition piece are grouted with UHPC concrete.

The UHPC concrete connections evenly distribute the forces from the three-legged transition piece to the piles

Tripod

A Tripod support structure/foundation is secured in place by driving three piles into the seabed through a sleeve in each of the three corners.

UHPC concrete is pumped into the annuli between pile and sleeve to ensure a strong and durable connection.

Jacket

Jacket foundations are secured to the seabed by four piles placed in a sleeve in each corner and driven into the seabed. Jackets are generally considered to be better than monopiles for seabeds where the substrate is poor or deeper water. So here UHPC grouting can be used in the "transition piece" and in the lower foundation.

Gravity foundations

Are well suited for rocky sea beds. The complete foundation system can be manufactured on land and then pulled into position with a ship and then sunk. Depending on the design, the entire foundation piece can be made from UHPC. UHPC will be perfect for slip casting the entire foundation.

                                                       
After the use of UHPC grout in offshore wind energy generation, the experience gained in onshore wind energy production has also been exploited.

Steel Tower

So far, steel towers in cylindrical or conical segment construction have been the state of the art.

Depending on the required hub height, up to five segments were mounted on top of each other. With the new tower heights, the segment diameters are getting bigger and bigger and the road transport between production and the site is becoming an ever greater problem.

Concrete Tower

More and more, as an alternative to steel towers, concrete towers are also produced and assembled in cylindrical, conical or polygonal segments. A disadvantage compared to the steel towers is the high wall thickness, which makes larger foundations necessary

The advantage is

• Favorable vibration characteristics, which leads to reduced noise emissions.
• Long life expectancy
• An ideal solution for high tower high and large rotor diameter
• Transport cost savings due to possible on-site manufacture
• The use of special UHPC concrete grades can lead to slender constructions and thus rougher component weight.
• Lower component weight can also make the foundation dimensioning more favorable, which can lead to cost reduction. The material experiences in the offshore transitionpiece technology can also be of advantage when using UHPC grout in the imbed ring assembly (connection tower / foundation).
• Since UHPC concrete of high quality have virtually no pore formation, they are extremely resistant to corrosion.
• There are little or no maintenance costs.
• The individual segments can be transported more cheaply than is possible with the steel segments.
• On-site fabrication is the use of slipforming is another option including the use of local concrete raw materials for the production of high-quality UHPCs.
• Furthermore, it is possible to produce extremely exact segments with UHPC grout material, which requires no or very little post-processing of the segment abutment surfaces.
• Our UHPC materials reach at least 70% of their rated strength in less than 48 hours, which can lead to lower manufacturing costs for segment production and delivery times can be drastically reduced.

Hybrid towers

This type of tower construction is a combination of concrete (lower part) and steel construction (upper part). IT combines most of the advantages of steel tower and accentuated tower technology. Here, too, the use of UHPC can lead to additional benefits and savings in terms of material and financial resources.
A segment construction or on-site casting by slipforming are possible. This reduces the costs of transport and reduces the foundation geometries.

 

WPE DK International

Phone: 0049 176 601 73146
E-mail: info@wpe-dk.dk
Homepage: www.wpe-dk.com

                                                        

UHPC - What do we understand by this and what does your customer mean?

Are you sure you do not compare oranges with bananas ????

Today's state

Today, there are a variety of so called UHPC Ultra High Performance Concrete products available on the international market.

Every concrete quality is described very precisely in the technical literature. There are well defined general material tests. Every architect and structural engineer can work with these defined values.

For more than 30 years we have been developing and producing UHPC for a variety of applications whether in architecture, offshore, security, road construction, bridge construction, tunnel construction etc.
In this long period of time, no one has succeeded in establishing a clear, worldwide definition of UHPC. It will probably never be possible.

An explanation attempt

Ultra High Strength Concrete was developed in 1981 with a compressive strength of more than 120 MPa /17500 psi. Since this newly developed binder has found a hitherto unprecedented range of possible applications, the term Ultra High Performance Concrete was developed. This generally used product designation is exclusively focused on the word performance and is therefore not a technical specification.

The word analysis

UHPC = Ultra High Performance Concrete

Ultra = Extreme, Special, Exceptional

High = Very intense, Powerful, Strong

Performance = Performance, Exercise, the act of performing, presentation, to carry out an action

Concrete = Formed of concrete, a compact mass of sand, gravel, cement and water

Elvis, Michael Schumacher, Michael Jordan, Neil Amstrong, a 747 Jumbo Jet, a Rolls Royce had an Ultra High Performance, but did they perform in the same way? No, you cannot compare them.

The original idea of an Ultra High Strength Concrete with a minimum compressive strength of 120 MPa / 17500 psi plays no decisive role in this performance.

The most important characteristics of the Ultra High Performance Concrete are made by a

special cementitious added with mineral, metallic, organic, non-metals, inorganic non-metallic additives or aggregates. The water/cement ratio should be below 0,20.

The next generation of UHPC materials has already been developed and is being processed - UHPC desert sand concrete. It will no longer be necessary for some countries to destroy their rivers and beaches or to transport sand around half the planet.

We are working on a product specification that allows every customer to ensure that they get the highest quality UHPC Ultra High Performance Concrete.

 

 

 

WPE DK International

Phone: 0049 176 601 73146
E-mail: info@wpe-dk.dk
Homepage: www.wpe-dk.com