Sharp sand is a construction and landscaping aggregate. It is distinguished by its coarse grain size and angular shape. Unlike smoother sands, which have naturally rounded edges, sharp sand’s grains possess rough, jagged surfaces that create a gritty texture. It is often sold under alternative names such as grit sand, coarse sand, or concreting sand. The material is also characterized by a low content of fine particles like silt and clay, which influences its performance in various applications.
Structural Mixes and Screeds
The angularity of sharp sand provides the necessary mechanical interlocking to create strong, load-bearing structural mixtures. When used in concrete, the jagged edges of the sand particles grip onto the cement paste and larger aggregates more effectively than rounded grains could. This superior bonding results in a hardened concrete mix with higher compressive strength and durability, making it suitable for foundations and footings.
Sharp sand is the preferred aggregate for producing floor screeds used to achieve a level surface over a concrete subfloor. A typical semi-dry screed mix uses a ratio of approximately four parts sharp sand to one part cement. The sand’s coarse texture ensures that the final screed layer is dense and robust enough to resist cracking and accommodate the eventual floor covering. Using fine, rounded sand compromises the interlocking action, leading to a weaker, less stable screed prone to shrinkage and failure.
Paving and Hardscaping Beds
In hardscaping, sharp sand is widely used as a foundational bedding layer beneath external surfaces like patio slabs, flagstones, and block paving. Its coarse, angular structure enables the grains to tightly interlock when compacted, forming a stable, non-rigid base. This firm bedding layer resists lateral movement and shifting, ensuring that the paving stones remain level over time, even under regular foot traffic or vehicle weight.
The low silt and clay content makes sharp sand an excellent material for drainage in hardscape construction. The gaps between the coarse, interlocking particles allow water to permeate rapidly through the bedding layer. This permeability prevents water from pooling underneath the paving, which helps prevent freeze-thaw damage during colder months. It is typically laid over a compacted sub-base of crushed stone to provide overall structural stability for the hardscaping project.
Horticultural and Drainage Applications
Sharp sand’s particle size and angular shape make it highly effective for improving poor soil structure. When mixed into heavy clay soils, the coarse grains physically separate the fine, dense clay particles, which dramatically improves soil aeration. This action increases the number and size of macro-pores in the soil, facilitating gas exchange and allowing plant roots to access necessary oxygen.
The improved structure significantly increases the soil’s permeability, allowing excess water to drain more freely and preventing the waterlogging that can lead to root rot. Gardeners commonly mix sharp sand into potting substrates for plants like cacti and succulents, which require a highly porous, fast-draining medium. For lawns, sharp sand can be applied as a top dressing after aeration to fill the holes, providing drainage channels and reducing surface compaction in the root zone. Some specialized horticultural sharp sand is washed to remove any mineral salts or lime that could potentially alter the soil’s pH balance.