C.7 PIONEERING USE OF REINFORCED CONCRETE

One of the most significant technical developments in the field of construction was reinforced concrete, which was invented by combining two widely used materials. concrete and steel. The first reinforced concrete building in Bizkaia was the La Ceres flour mill, constructed at the turn of the 20th century. It was seen as a symbol of innovation and openness to world trends. The Punta Begoña Galleries followed soon afterwards, as the first residential construction in the region to be built with this technique.

More than a century ago this was a pioneering technique. Concrete is an artificial stone made up of natural aggregate (sand and gravel) held together by a binder, usually in the form of cement. Various types of cement can be used, though one of the most widespread is Portland cement. The strength of concrete made with Portland cement can be increased by pouring it over steel tubes, bars, wire rod or mesh before it sets. The most widely used reinforcing material is steel, because its heat dilation is similar to that of concrete. The alkalinity provided by Portland cement means that once the concrete has set the steel is corrosion proof, and sticks well to the concrete. Adherence can be substantially improved by using corrugated steel bars.

Portland cement was apparently used at the Punta Begoña Galleries, because analyses on one of the façades have revealed traces of alite and belite, two silicates which are typical of this type of cement. These two silicates are turned into hydrated calcium silicate by the hydration process of the cement. It is no surprise that these materials were used here, given that the many business ventures of the owner Horacio Echevarrieta included a Portland cement plant in Toledo.