What is sand?

Sand is a loose, granular material formed by the weathering and erosion of rock, with grains between 0.063 and 2 mm. Finer particles are classed as silt and clay, coarser ones as gravel. Sand has been deposited by water or wind and in north-western Europe consists mainly of quartz (silicon dioxide). That is also why sand is the main raw material for glass.

Properties as a foundation soil

• Low compressibility: sand gives good bearing for buildings and roads.
• Permeable: rainwater drains away quickly, which makes sand suitable as a drainage layer.
• Grading matters: in sand with a range of grain sizes, small grains fill the voids between larger ones. The result is denser and firmer than sand with nearly uniform grains.

Compared with clay and peat, sand is a favourable building soil: it carries more load and settles less.

Application

• Aggregate in masonry mortar, plaster, sand and cement screed, and concrete.
• Filling sand to raise ground levels and as a sand bed beneath foundations and paving.
• Paving and jointing sand for laying and brushing in paving.
• Raw material for sand-lime bricks and glass.

Types of sand

By origin, a distinction is made between river sand, dune sand and sea sand, among others. River sand is often well graded and therefore suitable for concrete. Dune sand is fine and very uniform, which makes it less suitable. Sea sand contains salt and shell fragments and must be washed before it is used in concrete.

Types of sand and their suitability for concrete

River sand	Often well graded, therefore suitable for concrete
Dune sand	Fine and very uniform, which makes it less suitable
Sea sand	Contains salt and shell fragments; must be washed before it is used in concrete

Practical tips

1. Buy the right sand: concrete sand, building sand, filling sand and paving sand differ in grain size and purity. Never use filling sand for concrete.
2. Ask for the grading for concrete and mortar work. Aggregates for concrete must comply with EN 12620.
3. Compact sand beds in layers with a plate compactor so that paving or foundations do not sink later.
4. Mind the moisture: wet sand holds a lot of water. Allow for this when adding mixing water.

Related terms

• Quartz
• Gravel
• Clay
• Silt
• Filling sand
• Crusher sand
• Aggregates

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