Screed Calculator Sand & Cement

Screed Mix Equations:

\[ \text{Cement (kg)} = \left[\text{Area (m²)} \times \text{Thickness (m)} \times 1.33 \times \left(\frac{1}{1 + \text{ratio}}\right)\right] \times 1440 \] \[ \text{Sand (kg)} = \left[\text{Area (m²)} \times \text{Thickness (m)} \times 1.33 \times \left(\frac{\text{ratio}}{1 + \text{ratio}}\right)\right] \times 1600 \]

Cement Required:

Sand Required:

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1. What is Screed Mix?

Screed is a thin layer of cement and sand mixture applied to concrete floors to provide a smooth, level surface. The most common mix ratios range from 1:3 to 1:5 (cement:sand) depending on the application.

2. How Does the Calculator Work?

The calculator uses these equations:

\[ \text{Cement (kg)} = \left[\text{Area} \times \text{Thickness} \times 1.33 \times \left(\frac{1}{1 + \text{ratio}}\right)\right] \times 1440 \] \[ \text{Sand (kg)} = \left[\text{Area} \times \text{Thickness} \times 1.33 \times \left(\frac{\text{ratio}}{1 + \text{ratio}}\right)\right] \times 1600 \]

Where:

1.33 — Factor accounting for compaction and wastage
1440 — Density of cement (kg/m³)
1600 — Density of sand (kg/m³)
ratio — Cement:sand ratio (e.g., 4 for 1:4 mix)

Explanation: The equations calculate the volume of material needed, then convert to weight using material densities.

3. Importance of Accurate Mixing

Details: Proper mix ratios ensure adequate strength, workability, and durability of the screed. Too much cement can cause cracking, while too little weakens the mix.

4. Using the Calculator

Tips: Measure area accurately in square meters. Typical thickness ranges from 50-75mm (0.05-0.075m). Common ratios are 1:3 to 1:5 for different applications.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical screed thickness?
A: Residential floors usually 50-75mm. Commercial floors may be thicker (75-100mm) depending on load requirements.

Q2: Why 1.33 multiplication factor?
A: Accounts for compaction during laying and typical material wastage (about 25-30% extra).

Q3: Can I use this for other mixes?
A: This is specifically for cement-sand screed. Other mixes (with additives or aggregates) require different calculations.

Q4: How long does screed take to dry?
A: Typically 1mm per day up to 40mm, then 0.5mm per day beyond that (e.g., 50mm takes about 60 days to fully cure).

Q5: Should I add water reducer?
A: For large areas or hot conditions, plasticizers can improve workability without weakening the mix.