Concrete, that traditionally solid, substantial building material, is getting a makeover. Engineers have now developed concrete mixtures that are capable of transmitting light. By switching the ingredients of traditional concrete with transparent ones, or embedding fiber optics, translucent concrete has become a reality. As with any new material, it is expensive and still has some issues to be resolved. However, this innovative new material, while still partially in the development stages, is beginning to be used in a variety of applications in architecture, and promises vast opportunities in the future.
The Paradox of Translucent Concrete
When you think of concrete, most likely, your mind conjures up images of something solid, heavy, and monolithic. But what if concrete could be translucent, transmitting light into spaces, making them seem light and airy? Engineers today are challenging concrete to shed its opaque reputation to become both window and wall, simultaneously glowing, ethereal, and structural (see Fig. 1). Concrete has been called an “indispensable medium,” the “quintessential material” for architects and engineers, due to the vast “sculptural and expressive possibilities” that it can achieve . Now engineers are expanding those possibilities by modifying the basic ingredients of concrete to create translucent concrete. They are addressing the challenges and problems that occur in every new material, and some companies have started production. In the future, as translucent concrete becomes easier to manufacture and more available, engineers and architects will be able to utilize this amazing material in everything from furniture to entire buildings.
What Makes Concrete Concrete
Concrete has been used since Roman times, but its basic components have remained the same. Three ingredients make up the dry mix: coarse aggregate, consisting of larger pieces of material like stones or gravel; fine aggregate, made up of smaller particles such as sand; and cement, a very fine powder material that binds the mix together when water is added . Modern concrete is most often reinforced with steel, a practice that was developed in the 1850s . The simple formula for concrete, however, lends itself to endless modifications. By simply adjusting the ratio of ingredients, engineers can change the strength and texture of the material . Bigger aggregates lead to rougher concrete and vice versa. Other ingredients, known as admixtures, can be added to alter the concrete’s drying time, workability, color, and consistency . By switching ingredients and adding new ones, engineers have been able to create a multitude of interesting new products, one of which is translucent concrete.
How Translucent Concrete Is Made
Engineers have come up with several potential types of mixtures for translucent concrete. One approach is to exchange the traditional ingredients with transparent or translucent alternatives. Pieces of plastic or glass can be used as aggregates, and the binding agent can be switched with a type of transparent glue . Will Wittig at the University of Detroit Mercy in Michigan combined white silica sand and white Portland cement, and by “varying the ratios”, developed a mix that could be cast much thinner than traditional concrete . His thin translucent concrete blocks were reinforced with “short strands of fiberglass” and were able to transmit a glow of light . A company in Italy has also created their own secret recipe, using a combination of transparent resins as the binding agent . Aggregates can be replaced with transparent alternatives, and the bonding material itself may be able to transmit light by incorporating clear resins in the mix.