This new material was developed by Bouygues in partnership with Lafarge and Rhodia under the generic name “Reactive Powder Concrete, RPC” and is marketed under the brand name Ductal®.
Ductal is an ultra-light concrete and reaches compressive strengths of 170 to 230 MPa. It is composed of cement, water, sand, silica fume, silica flour, superplastifier, and steel micro fibres.
- Compressive strength 170 MPa – 230 MPa
- Flexural Strength40 MPa – 50 MPa
- Young’s modulus of elasticity 50 GPa – 60 GPa
- Total Fracture Energy 20 000 J/m2 – 30 000 J/m2
Ductal® offers the following advantages:
- It is used without conventional rebar
- It is fluid to self compacting
- Thanks to its impermeability, it is highly durable with minimum future costs of maintenance
- It allows for design of extremely subtle and light structural elements, which brings savings in costs of other load bearing parts of the structure, transport and the assembly itself
- It is resistant against aggressive environmental conditions and extreme climatic conditions
- It provides an absolute freedom for designing structural elements of any shape
In structural applications, Ductal® is reinforced with steel fibres with Ø 0.2 mm and the length of 13 mm, which are provided to withstand secondary tensile stresses due to shear, tension, small bending moments and concentrated loads. Where large bending loads are transmitted, the structures made of Ductal® need to be pre-or post-tensioned.
Sometimes the use of concrete is excluded, because it is either considered to be “raw” material or does not meet the requirements for making an extremely slim structure. Ductal® offers the possibility of designing a very subtle structure from an extremely resistant material, as well as a diversity of textures and colours. It is not reinforced with any rebar and so there are no space limits, only strength and deformation ones.
In construction of buildings, the largest portion of the load comes from the own weight. In average, 65% of load is the dead load and only 35% is applied load. When Ductal® is used, the dead load is reduced up to 1/3, which results in considerable savings in costs of other parts of structure and its overall lightening.
In non-structural applications, Ductal® is used with non-metallic fibres.
Ductal® has the ability to replicate the micro and nano-texture of the mould. When combined with the fluidity, the ability to have a range of colours, and high quality of the surface appearance, the result is a material that offers other, not only architectonic applications.