Due Diligence for Responsible Sand and Silicate Supply Chains

Annex B. End-use cases

Table A B.1. Sand and silicate use in the built environment

Use		Description
Construction materials and products for residential and non-residential buildings	Architectural concrete products	Architectural concrete products encompass a wide range of specialized concrete elements designed to enhance the aesthetic appeal and structural integrity of architectural projects, including decorative facades, countertops, and intricate paving elements.
	Bricks	Bricks are a fundamental building material known for their strength and durability. They are typically made from fired clay, a naturally occurring fine-grained soil. The clay is molded into individual units and then baked in a kiln at high temperatures. This process hardens the clay, transforming it into strong and weather-resistant building materials.
	Cement	A material used in construction that binds sets, hardens, and adheres to other materials to bind them together. It is fine powder typically produced by heating a mixture of limestone and clay (or similar materials) at high temperatures in a kiln.
	Concrete	A composite material made by mixing cement, aggregate (sand, gravel, rocks), and water. The cement hydrates (reacts with water) and binds the aggregate together to form a strong, durable material. There are many individual recipes for concrete, depending on different purposes.
	Engineered stone	A manufactured material combining crushed quartz or other stone with resin, offers a durable and stylish alternative to natural stone for countertops and flooring.
	Float glass	Float glass, the ubiquitous transparent material in windows and countless other applications, is a type of sheet glass. Sand, soda ash, and limestone, melted together at high temperatures to form the molten glass base.
	Plaster	Plaster is a versatile building material traditionally used for creating smooth surfaces on walls and ceilings. It is a mix of a binder, such as lime or gypsum, combined with sand and water. Once applied and dry, plaster hardens into a strong and fire-resistant surface.
	Natural stone	Valued for its beauty and durability, natural stone is used in various applications including countertops, flooring, wall cladding, and architectural elements.
	Structural, unbound materials	Materials used to create stable foundations or bases for various structures without the use of binders like cement or asphalt. These materials include aggregates such as gravel, crushed stone, or sand, which are compacted and layered to provide stability and support. Unlike bound materials, which rely on a binder to hold them together, structural, unbound materials rely on compaction and interlocking particles to achieve stability.
Buildings and infrastructure, including transport infrastructure	Disaster risk reduction / resilience investments	Before and during disaster events, sandbags are used to stabilise slopes prone to landslides. Silicate-based geotextiles reinforce riverbanks, preventing erosion during floods. Construction aggregates and other silicates are vital materials for interventions to reduce disaster risks and for building back after disaster events. In addition to the basic role they play in construction (see above), sand and silicates contribute to disaster-resilient construction whether as part of reinforced concrete and steel production, base isolation building techniques or replenishment of storm-affected beaches and dune systems (see below).
	Road network development	Sand and gravel are used to create robust foundations in road building. These are vital fill material, used to level the road surface and fill any gaps or cracks, ensuring a smooth and even roadway. Through compaction, it forms a sturdy base while also facilitating drainage around pipes, preventing water from pooling on the road surface. Tarmac or asphalt road surfacing sees these materials mixed with bitumen or tar to create a durable and smooth surface that can withstand the weight of vehicles and the rigors of everyday use.
	Airport and port infrastructure development and extensions	Reclamation for airport and port development is especially common in the Middle East, Southeast and East Asia, along with West Africa in line with significant infrastructure investments being undertaken in these regions (see Land Reclamation below). Kansai International Airport in Osaka, Japan is constructed on an approximately 11km2-large artificial island.
	Railway ballast	Igneous and metamorphic rocks are preferred for railway ballast in view of their high strength and abrasion resistance. There is no need to meet specifications for polishing resistance, and so rocks which are unsuitable for road use might justifiably be quarried for railway ballast and be transported relatively long distances.
	Artificial Island construction	Artificial islands are intentionally constructed landmasses in bodies of water, created through methods like land reclamation or valley flooding. They can support entire communities with housing, amenities, and infrastructure, or serve industrial and commercial purposes such as offshore oil platforms, port facilities, or support for bridges and other structures. Notable examples include the Netherlands (970 km2) and Japan (Kansai International Airport: approximately 11 km2), with a growing trend of island additions worldwide (Fisher and Hirschfeld, 2022[180]).
Land reclamation, flood management and coastal zone management	Beach nourishment	Beach nourishment, also known as replenishment, involves replacing lost sediment, typically sand, through human intervention due to longshore drift or erosion. It's a crucial part of coastal management, enhancing resilient shorelines amid rising sea levels. Sand is sourced from suitable offshore sites and transported to shore by pumping or shipping. While often considered environmentally friendly, the process can have significant short- and long-term effects due to the large volumes involved. Questions are arising over the cost-effectiveness and sustainability of this shore protection measure (Eiko et al., 2021[181]; Cusick and E&E News, 2024[182]).
	Coastal land reclamation	Land reclamation transforms submerged coastal areas into usable land for development. It's a longstanding practice in low-lying and space-constrained countries, with The Netherlands and Singapore frequently cited examples. However, large-scale reclamation is a more recent trend. A 2023 study reveals that 106 major coastal cities (population >1 million) have added 253,000 ha of land over the past 25 years, driven by urbanisation, global trade, and a desire for green spaces. Technological advancements also play a crucial role in enabling such large-scale projects (Sengupta et al., 2023[183]).*
	Flood management infrastructure	Floodplains undergo constant transformation, gradually accumulating sediment, such as sand, over time. This process serves as a natural mechanism to alleviate the effects of flooding on a broader geographical scale. Additionally, sandbags serve as a widely employed tool for flood control, functioning as prompt barriers adept at impeding the advance of floodwaters and safeguarding properties against potential harm.
	Natural delta and coastal replenishment	Rivers transport sediment to the coast, shaping deltas, beaches, dunes, and barrier islands along the way. Deltas like the Nile, Amazon, Mekong, and others are not only vital for natural processes but also serve as crucial agricultural hubs, population centers, and provide protection against coastal erosion (Neti, 2021[184]). On the seaward side, waves and tides shift sand along the coast to naturally replenish nearshore seabeds – important for wave attenuation and sea-life habitat, as well as carbon storage– as well as nourishing beaches, vital to coastal defense and tourism.
	Coastal climate resilience investments	Coastal erosion and disaster risk is exacerbated by climate change. Active built defenses go further by reducing wave force and expanding shorelines. Strategies include building artificial islands, reclaiming land, restoring dune systems, nourishing beaches. Built defenses like sea walls are typically made of reinforced concrete, armour stone, steel, or gabions, providing a solid barrier against waves. A shift towards sustainable approaches, including Nature-Based Solutions, which enhance resilience by harnessing natural processes like sediment flow from river systems is underway.

Note: *see MODUS 6 February 2024, ‘Out of the deep: 10 massive land reclamation projects’. Available at: https://ww3.rics.org/uk/en/modus/natural-environment/land/out-of-the-deep--7-massive-land-reclamation-projects--.html, last accessed 29 April 2024.

Table A B.2. Sand and silicate uses in energy production and storage

Products	Description
Frac sand, uses in oil & gas production	Silica sand serves as a proppant in hydraulic fracturing, where it is injected with water and chemicals into deep rock formations at high pressure, creating fractures that release trapped oil and natural gas deposits, with the sand maintaining these fractures open for improved oil and gas extraction, allowing oil and gas to flow more freely.
Geothermal energy	Silica sand serves a function in geothermal energy production as a proppant. Injected into wells under high pressure, it fractures rock formations, enhancing permeability and facilitating the flow of water and steam, thus improving geothermal energy extraction efficiency. Additionally, silica sand is utilised in geothermal heat pump systems, where it acts as a thermal energy storage medium.
Hydropower energy	Dams are structures constructed across rivers or streams to hold back or divert water for energy production. According to the International Energy Agency (IEA), hydropower is crucial for accelerating clean energy transitions to meet countries’ climate ambitions, producing large quantities of low-carbon electricity while offering flexibility and storage capabilities. (IEA, 2021[185]). Sand and silicates are vital for this infrastructure. While studies show a significant decline in the construction of large dams globally, construction is likely to continue, and maintenance and repair will be required until these structures are removed. Silica-based materials repair cracks, offering durability and chemical resistance. Silicate coatings protect concrete from water, chemicals, and weathering, while silica coatings enhance abrasion resistance for long-term maintenance. Silica sand aids in erosion control around dam spillways and embankments.
Solar energy	Solar panels are predominantly composed of silicon, derived from silica extracted from sand with a high silicon dioxide content heating it with a carbon material to produce metallurgical-grade silicon, which is then refined into high-purity silicon for solar cell manufacturing. The presence of silica sand significantly enhances the durability and longevity of solar panels, protecting the cells from environmental factors and reducing maintenance costs over time. Ultra-white embossed glass is used to protect solar panels, as well as increase the efficacy, insulation and resilience to agency. This glass primarily comprises raw materials such as quartz sand, soda ash, limestone, dolomite, sodium nitrate, mirabilite, sodium pyroantimonate, and aluminum hydroxide. Quartz sand serves as the main network-forming component, typically constituting over half of the glass composition.
Thermal Energy Storage	Heated silica sand provides a cost-effective method for storing thermal energy at temperatures as high as 1,200°C. This stored heat can be released from the silica sand and converted into electricity when there is a greater demand than supply, supporting electric power systems. Apart from its essential role in solar technology, silica sand is utilised in solar power plants to absorb and store solar energy as thermal energy during peak production. "Sand batteries" are also being explored as larger scale solution for heat storage. Low-grade sand is heated by cheap electricity from solar or wind and stored at temperatures of around 500°c for months on end.*
Transmission lines, energy grid	Ceramic and glass insulators, crafted from silica sand, are utilised in power transmission lines to bolster and insulate overhead cables, ensuring efficient transmission of electricity across extensive distances. Allied Market Research estimates that the global glass insulators market size was valued at USD345.8 million in 2021, and is projected to reach USD504.6 million by 2031.
Wind energy	Silica sand is widely used in the wind energy industry, particularly in the manufacture of wind turbine components. It is used as a molding material for casting metal parts such as turbine blades, bushings, and other critical components. The use of silica sand in the manufacture of wind turbines ensures high-quality, durable, and accurate parts that can withstand the harsh conditions and extreme forces experienced by wind turbines during operation. In addition to its use in the manufacture of components, silica sand is also used in the construction of wind turbine foundations.

Note: *Polar Night Energy is the Finnish company credited with the first, industrial-scale experimentation of this technology, aiming to provide reliable and affordable heat storage solutions for district heating and industrial applications. https://polarnightenergy.fi/.

Table A B.3. Sand and silicate uses in industrial production and products

Uses	Description
Automotive vehicle components	Sand and silicates contributing to various components and processes throughout the manufacturing process. Sand casting is used to form various metal parts of a vehicle, such as engine blocks and other componentshttps://www.iqsdirectory.com/articles/die-casting/sand-casting.html (see metal production).  Silica sand is a key ingredient in the production of safety glass used for windscreens and windows. It is also used in the production of tyres to improve traction and performance, particularly on wet surfaces. Silica-based materials are essential in manufacturing lightweight and high-strength composites used in vehicle bodies and interiors. Silicates are also utilised in paints and coatings, electronics systems and even battery innovation. High-silicon anode material increases the energy density of batteries without compromising safety or other performance parameters.*
Abrasives	Abrasives, widely used in industries like transportation, metal fabrication, and electronics, facilitate processes such as grinding, cutting, and polishing through abrasion with silica sand a key component, particularly in abrasive blasting for smoothing surfaces. Sandblasting is a process used for cleaning, smoothing, or shaping surfaces by propelling abrasive material against them at high speeds using compressed air or steam. While the term "sandblasting" suggests the use of sand, various abrasive materials can be employed depending on factors such as the desired surface finish, the material being worked on, environmental considerations and health concerns. For example, the use of quartz as an abrasive in sandblasting operations has now been forbidden because of the attendant risk of silicosis, and olivine is used as a substitute. The global abrasives market, valued at USD42.6 billion in 2022, is expected to grow to USD67.0 billion by 2032, with a CAGR of 4.7% from 2023 to 2032 (Allied Market Research, 2023[186]).
Food and beverage production and processing	Sand plays a role in nutrient circulation, soil amendment, growing media, and groundwater management relevant for food production. Furthermore, sandy aquifer material provides water storage. They play various roles in food processing, serving as additives, desiccants, and stabilisers. As additives, they are used in powdered form to prevent caking and clumping in food products such as powdered sugar, spices, and seasoning blends. Additionally, silicates are employed as desiccants to absorb moisture and prevent spoilage in packaged foods, extending their shelf life. Moreover, silicates act as stabilisers in certain food products, helping to maintain texture, consistency, and quality over time. Furthermore, the food processing sector relies heavily on glass packaging
Glass production	Glass is primarily composed of sand that undergoes transformation through high-temperature melting and shaping, with additives used to alter its colour, strength, clarity, and other characteristics. Approximately 40 million tonnes of glass are produced annually globally (Glass Alliance Europe, n.d.[76]). The most common type of industrial production, float glass, used for windows, mirrors, and architectural applications, is produced by "floating" molten glass over molten tin, resulting in a continuous, high-quality ribbon. Sheet glass, thinner and lower cost, is used in residential windows and picture frames. Safety glass includes tempered glass, heat-treated for strength and shatter resistance, and laminated glass, maintaining cohesion when shattered. Specialty glass types include borosilicate glass for laboratory use, fiber optic glass for light signal transmission, and high-purity quartz glass for scientific instruments and semiconductor manufacturing.
Metal production	Foundry, or casting sand, is clean high-quality silica used in metal casting processes to create moulds for shaping both ferrous and non-ferrous metals. Treatments like moistening or heating, and adding binders, the sand maintains its shape. In modern foundry operations, sand is frequently recycled and reused across multiple production cycles. Maintaining sand quality is paramount as inferior sand can lead to casting defects. Consequently, foundries and sand producers dedicate significant resources to quality control. Metallurgical silica, specifically processed for metal production, undergoes a purification process to achieve a high level of purity, typically around 98-99%. High-purity quartz is crushed and heated to extreme temperatures, approximately 1 500-2 000°C, in an electric arc furnace, often with a carbon source like coal or coke to reduce the silicon dioxide, eliminating oxygen and converting it to silicon metal. The resulting product, metallurgical-grade silicon aids in deoxidation during steel production, removing unwanted oxygen from molten steel. Additionally, it serves as an alloying agent, enhancing properties such as strength or corrosion resistance. Moreover, MGS can be employed as a raw material for the production of silicon carbide, a valuable abrasive material.
Textiles, footwear production	These materials are essential for making glass fibers woven into fabrics renowned for their strength, temperature resistance, and electrical insulation properties. These glass fiber textiles are utilised across industries like automotive and electronics. Silica sand contributes to textile treatment and finishing. For instance, sandblasting achieves a distressed denim appearance. They also aid in water purification processes within textile manufacturing. Moreover, silicates are integral to producing water-soluble sodium silicates, used as additives in textile printing paints and coatings, and in is used in some rubber shoe soles to enhance their durability and grip.
Water filtration, purification	In filtration systems, layers of sand are used to trap suspended solids, sediment, and contaminants as water passes through. Additionally, sand beds can also foster the growth of beneficial bacteria, aiding in the biological filtration of water. Sand filtration is widely implemented in various sectors, including municipal water treatment plants, swimming pool filtration, industrial water treatment, and groundwater remediation.
Other industrial applications	Sodium silicate, commonly referred to as water glass, is produced extensively for various applications, including detergents, chemical feedstocks, paper manufacturing, civil engineering, and adhesives. Silica aerogels, lightweight and insulating materials derived from silicates, can be used for storm-resistant windows and insulation. Silicate-based sealants enhance the durability of building materials, preventing water infiltration and wind damage.

Note:* Breakthroughs on silicon batteries can be explored at the following links, accessed in May 2024: https://group.mercedes-benz.com/company/news/mercedes-benz-and-sila.html; https://www.reuters.com/business/autos-transportation/new-silicon-anodes-could-help-ev-batteries-go-farther-charge-faster-2023-04-04/.

Table A B.4. Uses of sand and silicates in some major final consumer products and services

Products	Description
Cosmetics, personal care products	In makeup, minerals like mica and talc are commonly used for their shimmering properties, adding sparkle and gloss while also affecting the product's texture. When it comes to toothpaste, hydrated silica acts as a powerful abrasive, effectively removing stains, food particles, and plaque. Its compatibility with other toothpaste ingredients makes it a versatile choice. It is also being explored for skincare for its gentle exfoliating effect. Additionally, glass packaging (see Glass production) is a popular material for storing cosmetics and personal care items.
Electronics	Sand and silicates are indispensable in the production of consumer electronic goods, particularly in the semiconductor industry. Quartz sand (silica sand) is the primary source of silicon used in integrated circuits (ICs) and microchips. Silicon-based compounds derived from sand and silicates, including transparent conducting polymers, flame-resistant polymers, and liquid crystalline polymers, find applications in touchscreens, solar panels, flexible displays, and fire safety measures. Additionally, silicate glasses play vital roles in optical fibers, lenses, and camera sensors, exemplifying the broad impact of sand and silicates in modern electronics. In 2023, global silicon production amounted to an estimated total of nine million metric tonnes (Statistica, 2024[187]). This represents an increase from 2021, which saw the peak of silicon production during the period of consideration. China is the world’s largest silicon producer, with a production volume estimated at 6.6 million metric tonnes in 2023 (Statistica, 2024[188]).
Glass consumer products	In addition to soda lime glass commonly used for everyday glass packaging, other glass products have common uses in everyday consumer products including ophthalmic lenses in eyewear, display glass for smartphones and tablets, technical glass in sensors and lighting, and precision-molded glasses for cameras. Glass ceramics, combining the properties of glass and ceramics, find applications in cookware, cooktops, and optical components. Crystal glass is prized in luxury items, jewelry, and decorative pieces. The global glassware market was valued at USD 15.2 billion in 2021. It is projected to reach USD 25.4 billion by 2031, growing at a CAGR of 5.2% from 2022 to 2031 (Allied Market Research, 2022[189]).
Medical, health industry	Medical instruments, and other precision devices rely on specialised glass. Some silicon-containing compounds are used in pharmacological products for wound healing and hair growth. Commercialisation is growing for silica nanoparticles as drug delivery and skin treatment systems, though studies are also underway on toxic side effects (Nafisi, Schäfer-Korting and Maibach, 2017[190]).
Homeware, tableware, sanitary ware	Sand and silicates are key ingredients in producing various homeware items, from kitchen countertops to sanitary ware. Engineered quartz countertops are popular due to their durability, low maintenance, and aesthetic appeal. These countertops are made by combining natural quartz crystals (silica) with resins and pigments. The result is a non-porous, heat-resistant surface that withstands daily wear and tear. Some concrete countertops use silicate-based binders to enhance strength and durability. Silicate-based glass is used for wardrobe doors, cabinet panels, and mirrors. Silicate ceramics are commonly used for flooring and wall cladding in wardrobes and other interior spaces. Porcelain, made from kaolin clay and feldspar, is a type of ceramic known for its delicate, white body and smooth texture. It is made from high-quality clays and fired at high temperatures. Silicate glass is the foundation for drinking glasses, wine goblets, and decorative glassware. Ceramic toilets and sinks are made from silicate-based clay fired at high temperatures. Their non-porous surface ensures easy cleaning and makes it resistant to bacteria growth, promoting hygiene. Enamel, or vitreous china, is the silicate-based glassy coating applied to porcelain products, but also bathtubs, for durability and shine.
Tourism & recreation (Golf courses, equestrian facilities)	As just one example of tourism’s material dependence on sand, coastal and marine tourism accounts for roughly 50% of global tourism, equivalent to USD 4.6 trillion or 5.2% of the global GDP. This sector is particularly crucial for the economies of small islands and coastal communities. Of that, the global beach tourism market is projected to reach USD 152.3 billion by 2023, highlighting its substantial impact on the tourism industry as a whole (Northrop et al., 2022[78]). Sand is a major component of building and maintaining golf courses, particularly in creating bunkers and essential features for play as well as aesthetic benefits. Silica-rich sand, meeting required specifications for quality, particle size distribution, shape and colour, is applied on greens, tee boxes, and fairways. Additionally, sand is used for top-dressing, promoting turf health by improving surface smoothness, root growth, and soil aeration (Johnson, 2017[191]). Sand is integral to equestrian sport, especially in creating safe and functional riding surfaces. Equestrian arenas predominantly use sand as a footing material, with silica sand being a popular choice for its cushioning, shock absorption, and stability. The particle shape, particularly sub-angular grains, aids in creating a firm riding surface that supports horse movement. Properly graded sand ensures excellent drainage (Zorn, 2018[79]).