Concrete is a building material made of a mixture of water, sand, pebbles and cement, often defined as artificial stone.

A word considered to be of French origin, concrete is associated with engineering achievements – bridges, power plants, foundries.

Concrete as a material has been unchanged as a material since the 19th century, and the composition of concrete has undergone a few tweaks here and there, but its cold, hard, and gray aesthetic, until now. Translucent concrete is here to change the look of architecture.


Translucent Concrete

Translucent concrete was first mentioned in a 1935 Canadian patent by Bernard Long , who worked for glass manufacturer Saint-Gobain. In the ’90s, architect and inventor Bill Price explored the concept and even went as far as conducting strength tests on a few samples while working at Rem Koolhaas’s OMA . Yet it wasn’t until the early aughts, when Hungarian architect Áron Losonczi patented his light transmitting concrete LitraCon , that translucent concrete became commercially viable.

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Optical Glass Fiber

Light transmitting concrete is a mixture of optical glass fibres and fine concrete. It can be used as prefabricated blocks or panels. Thousands of optical glass fibres form a matrix and run parallel to each other between the two main surfaces of every block.

The proportion of the optical fibres it’s just a 4% of the total volume. Because of their size, they become a structural component in the concrete. The surface of the blocks therefore remains similar to homogeneous concrete.

The glass fibres lead light through the two sides of the concrete. Because of their parallel position the lighting on the brighter side of such a wall appears unchanged on the darker side. Shadows are displayed on the opposing side of the wall and the colour of the light remains the same.

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Structural Effects

In theory, a wall structure built out of Litracon can be a couple of metres thick. The fibres work with minimal loss of light up to 20m.

Load-bearing structures can also be built using these blocks, as glass fibres do not have a significant negative effect on the high compressive strength of concrete. The blocks can be produced in various sizes and also include embedded heat-isolation.

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Re-Designing Translucent Concrete

Translucent concrete is nowadays available in several varieties, but never before it was possible to make it insulating, until now. Zospeum is the first translucent concrete that provides both support and insulation, ready to revolutionise the way we see modern architecture.

Zospeum is a cutting-edge building material that uses up to 30.000 optical fibres per square meter of concrete. It allows light to permeate into living spaces in order for those on the inside to interact better with the outside world. It insulates while remaining strong, applicable for a multitude of architectural applications.

Allowing daylight to permeate helps with energy efficiency by providing natural illumination without ancillary heat. It reduces the need for additional lighting while saving on artificial ventilation.

Conceived by a team of leading designers in the Netherlands and spearheaded by architect Peter van Delft Westerhof, the foundation was set for a new concept that used insulation material alongside optical fibres. The core concept was built upon by Dutch construction agency Hurks , realising the original team’s ideas, bringing the translucent concrete to life.




As the most used building material, concrete is also the most intensively researched. Its potentials as a building material are still being discovered, allowing for new possibilities even after millennia of intermittent use. These most recent developments might seem like something from a science-fiction future, but they have all already been used in small construction projects and prototypes. Soon these emerging materials may be used to shape streets, buildings, and cities around the world.