2 Sand as a raw material
2.1 Creation and occurrence
Sand is created by the weathering of rocks. Over the years, rainfall, wind, frost and temperature fluctuations cause the solid compounds contained in the rock to break down into small particles. Calcareous sandstone weathers much faster than hard quarzite. The grains of sand are sometimes transported by wind, water and ice over long distances, whereby they are subjected to mechanical abrasion and rounded off. Finally, the grains of sand come to rest in geological deposits and are partially solidified again to sandstone. Fig. 2 qualitatively depicts the relative abundance of grain sizes in the the natural surface deposits of the earth. It can be seen that all types of sand account for a relatively small proportion, making up a total of only about 10 %. The amounts of gravel are twice as high, making up a total of 20 %. The largest amounts of about 45 % are accounted for by rock in the quarries of the earth.
2.2 Grain sizes and use in the construction industry
The mineral composition and colour of the sand varies widely. The most common sand consists mainly of quartz (silica = SiO2). In the construction industry, the relatively high hardness of quartz sand is a very welcome property (7 on the 10-stage Mohs hardness scale). For sand, a distinction is made between 3 particle size ranges. Fine sand has grain sizes of > 0.063 – 0.2 mm, while medium sand is defined as > 0.2 – 0.63 mm and coarse sand as > 0.63 – 2.0 mm. Smaller grain sizes below fine sand are referred to as silt, even smaller sizes below 0.002 mm as clay. Larger grain sizes than coarse sand are called gravel or chippings (from the crushing of natural stone). Gravel sizes are also subdivided into fine, medium and coarse. According to the usual conventions, material that is larger than 63 mm is called stones while anything larger than 200 mm is a boulder.
2.3 Market size and demand
Up to now, virtually no reliable data exists for the worldwide demand for construction sand and gravel. The available data concerning the industrial market in industrialized countries are slightly better, but except in the USA this market is mostly negligible compared to the amounts required by the construction industry. The situation is different when it comes to the economic importance of sand. The UNEP estimates a global market size of 40 bn t for construction sand and gravel. This figure is derived from the ratios of cement manufacture and aggregate production in the United States, where, over the last 2 decades, there has been a correlation with the factor 1 : 10. Derived from this, an estimated worldwide figure of 41 bn t is estimated for construction sand and gravel, based on the global cement production of 4.1 bn t in 2017. The market research firm Freedonia arrives at a similar figure of 40.2 bn t in its 2016 market study. However, this applies to all aggregates, including products from the crushing of natural stone.
On the basis of the market data from the USA, published in a lengthy time series by the US Geological Survey (USGS), the production figures for sand and gravel and the production figures for natural stone crushing result in a total of 2.49 bn t of aggregates (Fig. 4) or a per capita consumption of 7.6 t. Construction sand and gravel account for 39 % of that, while industrial sand and gravel come to 5 % and crushed natural stone takes the lion’s share of 56 %. In our view, it makes little sense to extrapolate these figures with the global demand for cement, since the USA alone accounts for almost 12 % of global construction spending, at US$ 1.3 trillion. This point becomes particularly obvious when comparing basic infrastructure data, such as the per capita transport network of roads, highways and railway lines, with the global average.
3 Market considerations, worldwide
In Europe (EU28), according to the UEPG (Union Européenne des Producteurs de Granulats), there are a total of some 13 900 companies extracting aggregates such as sand, gravel and natural stone. The number of operational sand and gravel pits and quarries is stated to be 24 540. Fig. 5 shows the production volumes for the year 2017, which is partially based on estimations. This indicates that the largest amount of aggregates is produced from crushed natural stone, at 1282 million tons per year (Mta) or almost 45 %, while 1097 Mta or 38.4 % are derived from sand and gravel and only 9.3 % come from the recycling of construction waste. On average, Europe has a per capita aggregate consumption of 5 tonnes. The main producers in the EU are Germany, France, Poland, the United Kingdom and Italy, which together account for nearly 63 % of the output (Fig. 6). The TOP 10, which also include Spain, Austria, Sweden, Romania and Belgium, account for a total of almost 80 %.
Fig. 7 shows the development of aggregates production in Europe (EU28 + EFTA). After 3.65 bn t in 2007, a decline bottomed out at 2.61 bn t in 2013. Since then, steady growth in production volumes has again been evident at around 2.5 to 3.5 % annually. The share of sand and gravel production in the total output of aggregates fell from 42 % in 2010 to 38 % in 2017. This is mainly due to higher recycling rates in building material production and partial coverage of the demand by industrial by-products (fly ash, steel mill slag) rather than limited availability of sand and gravel. In the EU28 + EFTA, about 163 Mta of cement were produced in 2017. Thus, if calculating on the basis of the proportions shown in Fig. 3, almost 545 Mm3 of concrete could have been produced, which would require about 1010 Mta of aggregates (of which 325 Mta would be sand). In fact, only about 261 Mm3 of ready-mix concrete was produced in 2017.
In the USA, approximately 970 Mta of sand and gravel were produced for the construction industry in 2018 by 3800 companies with approximately 9350 sand and gravel pits worth US$ 8.7 bn. In addition to this, an estimated 120 Mta of sand and gravel were produced for industrial applications with a market value of US$ 6.2 bn. 73 %, or around 88 Mta of this was supplied to the fracking industry, while 7 % went to the glass industry and 4 % was used as foundry sand. Fig. 8 shows how the production volumes have developed in recent years. In 2006, the production quantities of sand and gravel amounted to 1320 Mta. After 2007, output volumes decreased from 1240 Mta to 805 Mta in 2010. Since then, production figures have been rising again. For 2018, an increase of almost 8 % is expected. Industrial sand production, which suffered a slump in recent years, is expected to have increased by more than 17 % in 2018, thanks to the drilling of new oil wells.
According to current figures published by the Chinese Aggregates Association (CAA), more than 20 bn t of sand and aggregates are produced annually by more than 150 000 companies and are mainly consumed by the construction industry (Fig. 9). Concrete consumption alone accounts for 14.3 – 14.7 bn t if a cement consumption of 2.3 bn t is assumed. The consumption figure for construction sand alone is 4.8 bn t. This has become scarce in China. For years, the market prices of river sand, e.g. from the Yangtze, were largely stable at about 40 yuan/t (US$ 5.7/t). In the meantime, these prices have risen to 130 yuan/t, which corresponds to a price increase of 325 %. Two reasons are decisive here. Firstly, stricter requirements have been imposed for sand and gravel operations, and companies that did not meet the requirements have been closed. And secondly, there is an enormous ongoing demand from the construction industry. Less than 5 % of construction and demolition waste is currently recycled in China.
3.4 Other BRIC countries
In Brazil, the demand for aggregates increased from 340 Mta in 2000 by 6.2 %, to 745 Mta in 2013 (Fig. 10). Due to the economic and construction crisis in the country, demand then fell by 33 % to 497 Mta in 2017, with a per capita consumption of just 2.4 t. Since then, slight increases in demand quantities of 3.5 to 5 % per year have again been forecast. The ratios of the quantities of sand and gravel remained largely stable over the years with 58 % to 42 %. Up to now, no decline in the sand production rate has become visible.
Russia even shows a comparatively positive development. The production of aggregates increased from 422 Mta in 2010 to 706 Mta in 2017. The quantities for sand and gravel now amount to 282 Mta (40 %) after 163 Mta (39 %) in 2010. In percentage terms, the proportions of sand and gravel in the demand quantities are also unchanged in this country.
4 Major producers
Of the named companies, HeidelbergCement owns the world’s largest raw material reserves of 19 bn t, which will ensure the operation of their sand and gravel pits (Fig. 12) and quarries for the next 90 years. CRH is the leading company in North America, especially following its successful acquisition of Ash Grove Cement in 2018. CRH does not publish data regarding the total number of its gravel pits and quarries (Fig. 13). In the case of LafargeHolcim, the total number of its operations has recently exceeded 600 (Fig. 14), bringing it level with HeidelbergCement in this category. The next two places in the ranking go to Vulcan Materials and Martin Marietta (Fig. 15), both of which generate their largest sales volumes with aggregates. The TOP 7 is completed with Cemex, another cement giant, and Eurovia, a world leader in the transportation infrastructure industry and a member company of the VINCI Group.
5 Market trends and outlook
Freedonia predicted a 40.2 bn t growth in demand for aggregates at an annual average of 5.2 %, reaching a figure of 51.7 bn t in 2019. Their forecast saw crushed stone, recycled concrete, fly ash and blast furnace slag growing twice as fast as construction sand and gravel. Concrete would remain the largest market segment and the largest market growth would take place in the Asian/Pacific region. Basically, these assumptions are understandable, but they do require some comments. In particular, numerous experts see general declines in the availability of fly ash and concrete due to the CO2 issue . Also, the growth rates of recycled concrete and other construction wastes (Fig. 16) are hardly significant in most leading countries [3; 4] and, according to the UEPG trade association, even at a recycling rate of 100 % would only account for 12 to 20 % of the aggregate quantities required.
The main aspect that finds too little consideration in the a.m. market study are two important trends. Firstly, the trend towards machine-produced sands (Fig. 17) and secondly, the possibility of the construction sector making use of the huge quantities of overburden and tailings from the mining industry . This is already required in several countries, for instance China, where it has already been partially implemented. Finally, another piece of information is relevant: companies like VINCI are planning to produce high-performance concrete components using 3D printers (Fig. 18). This will, of course, demand the use of concretes with different properties, less cement and other optimum grain-size compositions, which will make future forecasts more difficult. By 2030, Dubai plans to build a quarter of its new buildings using this method.
Literatur • Literature
 UNEP: Sand and sustainability: Finding new solutions for environmental governance of global sand resources. GRID-Geneva, United Nations Environment Programme (UNEP), February 2019, Geneva, Switzerland
 Harder, J.: Development of clinker substitutes. ZKG 4/2019, pp. 42-51
 Harder, J.: Construction materials recycling – Market trends in Europe. AT MINERAL PROCESSING 11/2017, pp 44-56
 Harder, J.: Reutilization – Insights into the circular economy. recovery 2/2019, pp. 54-64
 Harder, J.: Tailings Management – Disposal of ore processing residues. AT MINERAL PROCESSING 07-08/2018, pp 52-65