Big sized vertical flaps for façade. Tordera, Barcelona.

These precast "flaps" are 7 m. long, 50 cm. wide, and 5 cm. thick, weighting 440 kg. each.

They've been manufactured with suitable iron anchors and plates embeded on, to connect to the building's structure.

The element's concrete can be considered as a Ultra High Performance Concrete(UHPC), constituted by cement in much higher dose, silica agreggates, nano-silica, glassfiber, and corrugated iron reinforcement (galvanized).

All the exposed surfaces of the flaps were silica-coated, color as per architect's choice.

In precast sollutions with UHPC concretes, we mind more to increase bending and tensile resistance rather than compressive. For these "flaps", bending-tensile resistance was higher than 5 MPa. at 48 h. and >11 Mpa at 28 days.

As the building is really close to the sea, another very important feature to control for the long term durability of these new concrete flaps is the absortion ratios. That we achieved lower that 0.1 grams / cm2 of exposed surface after submerged 24h. in water.

Self load for each flap hangs mainly from the structural top eave, but additional bottom and half-height fixings ensure the best connection of the flaps to the building structure.

All the fixing solutions of the projetc were bolted, Hilti-like.

First of all, a prototype flap mock-up was mounted in the façade to confirm the fixings solution fitted the service, and learn the optimal mounting sequence. Then the whole precast series entered production.

After the mock-up conclusions, a team of three workers and a technical supervisor sufficed to mount some 20 of these flaps / day, with reliable elevation means (which were rented by daily basis).

Architectural project solutions with precast façade flaps, are getting common nowadays, wordlwide. Their main purpose is to regulate light and shadows income, and aesthetic as well.

Precast flap type elements suffer typically of more fisuration problems, even cracking, than other kinds of elements. Therefore, experience with high resistance concrete is the key issue to ensure a good result, considering long-term durability too.