The best mix for laying slabs typically consists of 4 parts sharp sand, 1 part building sand, and 1 part cement. This ratio provides a durable and workable mortar bed.
This combination achieves a good balance between workability and strength. Here's a breakdown of why each component is important:
- Sharp Sand: Sharp sand, also known as coarse sand, provides the bulk and strength to the mix. Its angular particles interlock, creating a stable base for the slabs.
- Building Sand: Building sand, also known as soft sand or fine sand, improves the workability of the mortar. It makes the mix smoother and easier to spread, allowing for better contact with the slabs. Using building sand on its own is generally not advised as it tends to be too weak for slab laying.
- Cement: Cement acts as the binder, holding the sand particles together as the mortar sets and hardens. Portland cement is commonly used for this purpose.
The inclusion of both sharp sand and building sand is key. Sharp sand alone can create a mortar that is difficult to work with, while building sand alone results in a weaker, less durable base. The combination creates a mortar that is easy to use and provides a long-lasting, stable surface for your slabs.
Mixing Tips:
- Dry Mix First: Thoroughly mix the sand and cement in a dry state to ensure even distribution of the cement throughout the sand.
- Add Water Gradually: Add water slowly, mixing continuously until you achieve a plastic, workable consistency. Avoid adding too much water, as this can weaken the mortar. You're aiming for a mix that holds its shape and doesn't slump.
- Use a Mixing Platform: It is usually much easier to mix the material on a mixing platform or inside a wheelbarrow as it means that you can combine the material together easier.
- Consider a Plasticiser: For enhanced workability and frost resistance, consider adding a plasticiser to the mix according to the manufacturer's instructions.
Summary: The 4:1:1 ratio of sharp sand, building sand, and cement creates a strong and workable mortar mix ideal for laying slabs, ensuring a durable and aesthetically pleasing paving project.
