Concrete Innovation

Seite 1

Bendable Concrete

Formally known as Engineered Cementitous Composites (ECC)

Developed in 2000 by Michigan University.

Contains: sand, fly ash, water, fibres and admixtures.

It's tensile ductility reduces cracking & fracture problems.

Is designed to bend and crack in narrow hairlines rather than break & split in large gaps.

Can be used with common construction equipment.

Key Features & Characteristics

Ductile

Not brittle

300 times more deformable in direct tension than conventional concrete.

Tensile strain capacity of 3-5% compared with 0.1% of conventional concrete.

Can self-heal upon cracking.

Under shear tension failure mode it's loading capacity is increased by 50% and it's ultimate deformation by 200%.

Under shear compression failure mode it's load capacity increases by 50% and it's ultimate deformation remains the same.

The Need for ECC

Is an effective alternative to conventional reinforced concrete.

Case Study - Mitaka Dam, Japan

Severely damaged 60 year old structure.

Evidence of cracking, spalling & water leakage.

Successfully repaired in 2003 using ECC.

20mm layer of ECC sprayed onto 600m2 of the dam's surface.

Lafarge Ductal

Ultra-high performance concrete fibre reinforced concrete technology.

Improved micro-structural properties give it the capacity to deform and support flexural and tensile loads, even after initial cracking.

Concrete Canvas

Won material of the year 2009.

Once the cloth shelter is erected, the hardening process is started by adding water.

Originally designed for shelters, the British Army now use it to create fortified positions.

Self-Cleaning & Colour Change Concrete

Nano-scale titanium dioxide captures dirt particles which are washed away with rain.

Translucent Pre-Cast Concrete - Luccon

A fine grained concrete covered in fabric layers of synthetic optic fibres.

Strength & durability is comparable to high strength concretes.

Only works well when backlit.

Girli-Concrete

Designed by textile designer and an architect.

The concrete blends rough and smooth materials using textiles that are embedded and woven into the concrete.

Pervious Concrete

High porosity concrete created by a high void content.

Allows water from rain to pass through.

Reduces run-off and allows groundwater recharge, often used in parking areas, residential streets & walkways.

Has little or no fine aggregates but just enough cementitious paste to preserve the interconnectivity of the voids.

Self-Compacting Concrete (SCC)

Developed in late 1980s in Japan.

In Europe, was first used in civil works for transportation networks in Sweden in mid 1990s.

Since a multi-national industry led SCC project in 1997-2000, SCC has found increasing use in the EU.

Does not require vibration for placing & compaction as it is able to flow & compact under it's own weight whilst achieving the same engineering properties as traditional vibrated concrete.

Advantages of SCC

Noise eliminated

Healthier working environment

Reduced demand for skilled labour

Faster placing time

Improved surface finish

Reduction in making good costs

Disadvantages of SCC

More expensive - approximately £10-23/m3

More cement

Special mixes

Requires different handling

More QA tests on site required.

Improved formwork quality & increased pressures.

Nano?

Sustainability Pros & Cons of SCC

Pros - less noise & disruption and better health & safety.

Cons - still a cement based material & typically requires more cement.

Economic Applications for SCC

Precast elements

Exposed walls and columns

Watertight basements

Wall cladding

Dense reinforcement

Column encasement (e.g. Albion Wharf)

Top-down construction

Other Concrete Innovations

Termodeck - Precast cement slabs with holes through the centre to promote passive ventilation.

Holocore Slabs - Can integrate services in the slabs (e.g. HVAC services)

Pre-assembled concrete block walls.

Lightweight slabs (cobiax biaxial flat slabs - 35% weight reduction)

Insulated concrete formwork

Nudura - Claimed to be 6-7 times faster than traditional concrete wall construction.

Insulated Concrete Formwork (ICF) - Formwork is built using large, hollow polystyrene blocks which are filled with concrete & reinforcing bar as the project progresses, with the polystyrene remaining in place as an insulating layer to a completed structure.

Extensia - Reduced thickness industrial concrete floors (225mm thick to 175mm) without the need for joints & 20% carbon saving.

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