As architects from Beirut, Lebanon, we work on public spaces in developing countries. Those spaces are often disregarded, as left overs, when they are not just designed as technical road with only the cars requirements in mind. This unfortunate situation can be reversed and we are working to provide tools for the civil society to take over and regain calm and kindness to the city. We are working in the direction whereby we would address designing for public space as we would design for interiors, creating for urban voids sculptural and appealing pieces.

Concruence chair is an outdoor seat which can withstand any weather, it is made from concrete, the only local material that is entirely produced in Lebanon, which has no forests nor mines, but quarries for limestone which is heated using recycled oils into concrete by the local industry.

Extensive research and experimentation were invested into the shape, the material and the finishing of this piece, but most particularly its ergonomics to insure comfort while using only concrete.

The end life of the chair, despite being generation ahead, is panned: it produces an inert waste, which can be safely used in landfill, concrete aggregate and other because the chair has no metal reinforcement.

Name: CONcRUENCE

Congruence “Agreement or harmony; compatibility.”

Concrete "A building material made from a mixture of broken stone or gravel, sand, cement, and water, which can be spread or poured into molds and forms a stone-like mass on hardening."

GENERATIVE DESIGN

The chair is sculptural, low height, generously large, with voluptuous yet structurally logical shapes which have been obtained through generative design. Strength is obtained by geometry: a spine and stiffeners, smoothly integrated in the sculptural shape, are providing the needed beam height at the structurally logical points whereas the overall chair wall thickness is only 8mm thick.

PROCESS

Various scales of scale models were made, using 3D printing then our CNC 7 axis robot arm to create prototypes, to check iteration on the geometry and ergonomics, as nothing else but good design would provide comfort on a seat which is only made of concrete.

Four metal inserts are laid in the mold before the cast so the legs have an adjustable rubber pod for indoor on fragile grounds. Latex pads ensure a very tight contact with the ground. We have made various researches with fiber enhanced concretes. The color, the strength, the porosity have been worked out in order to give better results on several project we conducted.

CHARACTERISTICS

The weight of one chair is about 26 kg. It is envisaged as an outdoor chair that does not move much, but it can also find its place indoor where its sculptural quality can shine. A drain at collecting point allows the evacuation of rain water for the chair to support all year long outdoor exposure. The top surfaces being at the bottom during the cast: they are the least porous, which gives them a long lifespan, even in freezing regions. Finish is wax.

Concrete is one of the rare raw materials entirely made in Lebanon. It produces an inert waste at end of life, which can be used safely in landfill. But because we use fibers instead of steel reinforcement, it can also be recycled as aggregate in other concretes.