Sand and gravel
Two major groups of natural sand-gravel aggregates are differentiated: coarse aggregate group, comprising gravels and sand-gravel mix, and that of fine aggregates – comprising sands. Natural aggregates are used mainly in the building (concrete fill) and road construction (embankment and highway fill and road surfacing).
The demand for natural coarse aggregates is the largest, especially as distribution of their resources is far from uniform. The resources of natural coarse aggregates are generally small in central parts of the country, not covering the local demand.
According to criteria of Polish classification of reserves/resources adopted in 2005, exploitable gravel deposits (with up to
25 % share of fraction < 2 mm) and sand-gravel mix (25-50 % share of fraction < 2mm) should be characterized by content of grains of silt fraction below 15%, thickness not smaller than 2 m and the ratio of cover to deposit series not higher than 1.0.
Distribution of sand deposits is fairly uniform throughout the country, except for the south where in some regions their resources appear insufficient to cover the local needs.
The bulk of Polish natural aggregate deposits are of the Quaternary age. The share of deposits of the Pliocene, Miocene and Liassic age is subordinate.
The quality of raw material (especially its homogeneity) depends largely on genetic type of a given deposit. Deposits of fluvial origin clearly predominate in the Carpathian-Sudetic zone (southern Poland). In the Sudety Mts, the most common deposits are those of sandy-gravel higher terraces of the Pleistocene age, built mainly of detritus of sandstones and crystalline rocks. In turn, in the Carpathian region the raw material basis mainly comprises gravel and sandy gravel deposits occurring on flood-plain terraces as well as valley side terraces rising above flood plains. The Carpathian deposits are characterized by predominance of material coming from disintegration of flysch rocks, except for those of the Dunajec River valley, showing fairly high contribution of crystalline rocks from the Tatra Mts.
In northern and central Poland (Polish Lowlands region), the most important deposits are of glacial (accumulation platform of front moraine) and fluvioglacial (outwash plain and esker) origin and resulting from river accumulation. Deposits from northern part of that area represent gravel-sandy accumulations mainly comprising Scandinavian material – debris of crystalline rocks and limestones with admixture of quartz and sandstones. In central and southern parts of this region, the deposits are mainly formed of sandy sediments with significant share of debris of local rocks.
Sand and gravel deposits occurence in Poland is presented on the map.
Table 1 shows resources and the current state of exploration and development of natural sand and gravel aggregates.
Anticipated economic resources of natural aggregates totaled 16,752.42 million tonnes in the end of 2010. This means an increase by 507.31 million tonnes in relation to the previous year.
The largest resources were proven in the Dolnośląskie (2,071 million tonnes), Małopolskie (1,861), Opolskie (1,408), Podlaskie (1,254) and Podkarpackie (1,170) voivodeships.
In 2010, production of natural sands and gravel rose to 163.44 million tonnes, increasing by 22.4 million tonnes, that is
15.9 % in relation to the previous year.
The production was reported to be the largest in the Mazowieckie (20.6 million tonnes) voivodeship. The increase in production was the highest in the Mazowieckie voivodeship (by 6.3 million tonnes which corresponds to 43.7 %) and Podlaskie voivodeship (by 4 million tonnes - 45.8 %). High increase in production (for 3.6 million tonnes) was also reported from the Podkarpackie (61.7% increase) voivodeship.
Figure below shows changes in domestic resources and production of sand and gravel in Poland in the years 1989 - 2010.
In the case of natural sand and gravel aggregates, shipping distances have to be minimized because of high transport cost relative to value of these commodities. In table 2 there are presented directions of Polish sand and gravel export and import in 2010, table 3 shows directions of silica and quartz sands export and import and table 4 shows export and import of other sands.
- B - for solid minerals - mine in building process, for fuels - prepared for exploitation or trial period of the exploitation
- E - exploited
- G - underground natural gas storage facilities
- M - deposit crossed out of the annual report of mineral resources during analized period
- P - deposit covered by preliminary exploration (in C2+D category, for fuels – in C category)
- R - deposit covered by detailed exploration (in A+B+C1 category, for fuels – in A+B category)
- Z - abandoned deposit
- T - deposit exploited temporarily
- K - change of the raw material in deposit
Prepared by: Alina Piotrowska, Wojciech Miśkiewicz, Krzysztof Żukowski