Saving sand and building a sustainable future

Once thought to be limitless, sand is now a scarce resource. With an annual demand of 50 billion tons, twice the natural production rate, the need for sustainable alternatives is urgent. The sand demand has tripled in recent decades, and most of it is required by the construction industry to produce concrete. However, the type of sand used is very specific. The vast quantities of desert sand are unsuitable due to the fact that the grains are too fine and too round. As a result, the sand required is extracted from rivers, seabeds, and coastal areas, and transported over long distances to concrete manufacturers.

Unfortunately, this comes at a cost for the environment. Sand deposits are crucial, serving not only as protected biotopes for various species, but also as natural barriers that protect human habitats from erosion. According to the World Wildlife Fund, more than 70 countries around the world have banned the extraction of sand from riverbeds because of its negative impact on the environment. This has led to a decrease in the availability of high-quality sand and an urgent need to replace virgin sand in concrete production. For many years Sika has been developing solutions that allow the use of alternative sands in concrete and its own mortars. This makes Sika’s expertise in admixtures and additives more relevant than ever, as they facilitate the use of lower grade, recycled, or manufactured sand without compromising quality. 

RECYCLING OF OLD CONCRETE
AND MINE TAILINGS 

As sustainable practices are being adopted to reduce environmental impact, recycling becomes increasingly important in the construction industry. One of the key advancements in this regard is the ability to utilize sand derived from recycling processes. This approach not only conserves natural resources but also reduces waste, contributing to a more circular economy in construction. 

A prime example is Sika’s reCO₂ver® technology, which enables old concrete to be broken down into its original components: gravel, sand, and cement powder. As a result, the sand can be reused in the production of concrete and mortars, thus closing the loop in the material’s life cycle. Moreover, a chemical reaction during this recycling process also permanently binds around 15 kilograms of CO₂ per ton of demolished concrete. By incorporating a mechanism for CO₂ sequestration into the concrete recycling process, Sika’s techonology adds an additional layer of environmental sustainability.

Another significant alternative to natural sand is available by means of mine tailings. With an annual global production of 30 to 60 billion tons, traditionally, most of this material has accumulated into stockpiles, where it remains unused. Recognizing its potential, Sika has developed technologies to convert these mine tailings into alternative sand for high-quality building materials. This sustainable approach is already in place for Sika mortar production sites in China.

SHIFT TO ALTERNATIVE SANDS IN CHINA

China, home to the largest number of megacities in the world, continues to experience heightened construction activity. Because of this dynamic, Sika is rapidly advancing its efforts to replace virgin sand with alternative options in China, where it sells the largest volume of mortars annually. In 2021, Sika incorporated 5% of alternative sand in its production of mortars. This volume increased to 13% in 2023, with half of Sika’s plants in China already contributing to this initiative. By 2028, Sika China’s goal is to substitute 50% of its total sand requirements with alternative sand options.

Blueprint for the whole world  

Sika’s proven experience in China lays a solid foundation for global implementation. “Our focus is on the quality of mine waste rock, particularly heavy metal content,” says Luz Granizo, Core Technology Head Cementitious Systems. To prevent any environmental contamination through reuse, the company is conducting rigorous analyses of potential materials worldwide. In addition, Sika evaluates the energy required to process recycled materials and waste streams as input materials. This ensures that the recycled materials meet the highest standards of environmental safety and sustainability.

Recycling sand from concrete mud 

Sika France has found another innovative approach where concrete mud – the unhardened waste concrete from trucks and factories – is collected and washed by recycling providers, separating virgin sand and gravel from the cement paste. The recycled sand obtained through this process is used by Sika to replace natural virgin sand in various mortar products, including tile adhesives, masonry mortars, and facade mortars. The substitution ratio varies from 20 to 90% while still achieving the same high quality and performance of the products. 

This new approach not only provides an efficient recycling solution, but also helps alleviate environmental concerns. Traditionally, concrete mud has been landfilled or, in worse cases, dumped into rivers, raising pH levels and causing environmental damage. By diverting this material into the recycling stream, Sika is making a positive contribution to environmental protection and sustainability in the construction industry. 

All these advancements are made possible thanks to Sika’s century-long expertise in chemistry. Sika’s know-how helps reduce the use of virgin sand both in its own mortars and in the concrete produced by its customers.