The world is running out of sand. However, Sika has the solutions to solve this problem in the construction industry. Sand covers much of the earth’s surface, but sand isn’t just sand. In the industrial world, it’s an “aggregate,” a category that includes gravel, crushed stone, and various recycled materials. Natural aggregate is the world’s second most heavily exploited natural resource after water, and for many uses the right kind is scarce or inaccessible.
When Quality Aggregates for Concrete run short – Sika’s Solutions to help to overcome this situation
In 2014, the United Nations Environment Program published a report titled “Sand, Rarer Than One Thinks,” which concluded that the mining of sand and gravel “greatly exceeds natural renewal rates” and that “the amount being mined is increasing exponentially.” The scarcity of high quality sand has become a challenge in the construction industry.
Sand-aggregate is the main constituent of concrete. Concrete is made from 10% of cement, which is composed of lime and clay, 15% of water and 75% of sand and gravel. These aggregates account for the bulk of the concrete and are a vital necessity for the entire composite. Judging from the numbers, sand and gravel are the most-consumed natural resource on the planet besides water.
Approximately 50 billion tons of sand and gravel are used every year, which is more than enough to blanket the entire United Kingdom. However, those extraction rates are exceeding natural replenishment rates, which has an impact on the availability of quality aggregates. This affects the entire construction industry as this resource has become a rare commodity.
The first step in optimizing concrete is to recognize that concrete is no longer simply cementitious materials, aggregates, and water. It is a high performance material consisting of not just four, but seven, essential elements: water, cementitious material, sand, gravel, chemical admixtures, additives, and fiber reinforcement.
Sika Solution to Overcome High-Quality Sand Shortage
Concrete admixtures can improve the sustainability of concrete in many different ways. Firstly, admixtures can significantly improve the quality and performance of concrete, which in turn extends its service life. In addition, thanks to the use of admixtures the application of concrete, instead of other building materials, can improve the life cycle of infrastructures, i.e. concrete roads greatly improve the quality and durability of highways compared with conventional road surfacing.
Furthermore, the addition of special admixtures, such as stabilizing or water reducing admixtures, also enables the use of alternative and recycled materials, such as recycled aggregates, for the production of good quality concrete. Finally, in many cases the energy required to produce certain cement or concrete mixes will be positively impacted with the use of admixtures. One example is the addition of water reducing and accelerating admixtures to obtain high early strengths in precast concrete to greatly reduce, or even completely replace, external heating of elements.
Sika concrete admixtures, such as Sika® ViscoCrete®, help to meet the challenges of modern concrete technology. They help to overcome the impacts the current and future aggregate situation is causing to the building sector by enhancing specific properties of the fresh or hardened concrete, such as workability, durability, or early and final strength.
For example, Sika® ViscoCrete 4027, one of the bespoke products within the portfolio, is recommended whenever there is a lower clinker content within the Portland cement. Sika® ViscoCrete 3095 N and Sika® ViscoCrete 3096 N are two admixtures which are beneficial if the sourced aggregates are recycled. The mentioned products do not only help to maintain the quality of the concrete, but also open a new possibility of reusage of aggregates instead of resourcing them form nature. This therefore helps counteract the shortage.
Since 2015, Parex, the company which was incorporated into the Sika Group in 2019, has achieved a 5% reduction in its greenhouse gas emissions in France. With a focus on the circular economy and finding ways of preventing climate change, projects that involve the use of recycled or bio-sourced raw materials were given priority. New solutions like PARNATUR®, the first “easy-to-spray” thermal and phonic insulation hemp-based mortar, contribute to the structuring of agricultural channels by promoting the use of bio-sourced aggregates in the building industry. Hemp concrete therefore is a 100% natural solution with a high CO2 storage coefficient and is fully recyclable.
Thermal and phonic insulation
Hemp is a natural material suitable for making lightweight insulating mortars. Its density varies between 110 and 150 kg. per m3, and the strands are between 2 and 10 mm long. The thermal conductivity of hemp in bulk is 0.04 W/m.K. Particular attention has to be paid in making sure that hemp is not subject to humidity, either due to stocking conditions of the raw material or capillary action in hemp mortars. Sika has launched a breakthrough innovation developed by the Sika Global Technology Center in France, and sponsored by Ademe, the French Environment & Energy Agency. Three worldwide patents have been secured.
The pumpable hemp-based insulating mortar has a thermal conductivity of 0,065 W/m.k. It has been tested and proved as an ideal solution to decrease thermal leakage across walls. Energy consumption can be reduced by up to 45% which corresponds to annual cost savings of CHF 2,000 for a home of 100 m2.