Best Sand For Lime Mortar in South Africa

Lime mortar has been used for centuries in construction due to its durability, flexibility and sustainability. When it comes to creating lime mortar, the choice of sand plays a crucial role in determining the quality and performance of the final product.

In South Africa, where diverse geographical regions offer different types of sand, selecting the right one is essential for achieving optimal results. In this guide, we will explore the factors to consider when choosing the best sand for lime mortar in South Africa.

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Understanding Lime Mortar

Before delving into the selection of sand, it’s important to understand lime mortar itself. Lime mortar is a traditional building material made by mixing lime, water and aggregates such as sand. Unlike modern cement-based mortars, lime mortar is breathable, allowing moisture to evaporate from the masonry, which helps prevent issues like trapped moisture and spalling. Additionally, lime mortar offers excellent flexibility, making it ideal for historic buildings and structures prone to movement.

Factors Influencing Sand Selection

Particle Size and Shape:
The particle size and shape of sand greatly influence the workability and strength of lime mortar. Ideally, the sand should have a well-graded particle size distribution with a mix of coarse, medium and fine particles. Coarse particles provide strength, while fine particles improve workability and bonding. Angular or sub-angular grains are preferable over rounded grains as they interlock better, enhancing the mortar’s cohesion.

Mineral Composition:
The mineral composition of sand affects its color, texture and reactivity with lime. Sands containing high levels of silica, such as quartz, are desirable for lime mortar as they provide strength and durability. However, excessive amounts of impurities like clay or organic matter can negatively impact the mortar’s performance, leading to poor adhesion and reduced durability.

Regional Availability:
South Africa boasts diverse geographical regions, each offering different types of sand. It’s essential to choose a sand that is locally available to minimize transportation costs and environmental impact. Moreover, using locally sourced materials aligns with sustainable building practices and promotes regional craftsmanship.

Compatibility with Lime:
Not all sands are compatible with lime due to variations in chemical composition and particle size distribution. Sands with high clay content or alkaline minerals may react adversely with lime, leading to shrinkage, cracking or efflorescence. Conducting compatibility tests by mixing small batches of lime mortar can help assess the suitability of different sands before large-scale use.

Recommended Sands for Lime Mortar in South Africa

River Sand:
River sand is one of the most commonly used sands for lime mortar in South Africa. It is naturally well-graded with a mix of coarse and fine particles, offering good workability and bonding properties. River sand is typically composed of quartz grains, making it suitable for lime mortar applications. However, sourcing river sand responsibly is important to minimize environmental impact and preserve river ecosystems.

Dune Sand:
Dune sand, found along coastal regions, is another viable option for lime mortar. It tends to have a higher salt content compared to other sands, requiring thorough washing before use to prevent salt-related issues like efflorescence. Dune sand is often finer in texture and may require adjustments in lime-to-sand ratio to achieve the desired consistency and strength.

Crushed Stone Sand:
Crushed stone sand, also known as manufactured sand or crusher dust, is produced by crushing and screening coarse aggregates. It offers a consistent particle size distribution and is free from organic impurities. While crushed stone sand can be suitable for lime mortar, attention should be paid to the source material to ensure it meets quality standards and does not contain contaminants.

Desert Sand:
In arid regions like parts of South Africa, desert sand is abundant but may pose challenges for lime mortar applications. Desert sand often has a high salt content and contains rounded grains, which can affect the mortar’s performance. Treating desert sand through washing and sieving processes can help improve its suitability for lime mortar, but extensive testing is recommended to assess its compatibility.


Choosing the best sand for lime mortar in South Africa requires careful consideration of factors such as particle size, mineral composition, regional availability and compatibility with lime. While sands like river sand and dune sand are commonly used, other options like crushed stone sand and desert sand can also be viable with proper preparation and testing. By selecting the right sand and adhering to proper mixing techniques, builders can create lime mortar that not only preserves historical structures but also promotes sustainable construction practices for the future.
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