Calculate concrete shrinkage strain, crack risk, V/S ratio, and recommended joint spacing for your slab project.
1. Select Units: Choose between Imperial (ft/in) or Metric (m/mm) at the top of the input section.
2. Enter Dimensions: Input the length, width, and thickness of your concrete slab.
3. Set Environmental Factors: Enter the expected ultimate shrinkage rate (microstrain), ambient humidity, curing days, and the current age of the concrete.
4. Review Results: The calculator instantly updates the total shrinkage, V/S ratio, crack risk, joint spacing, and material volume. The 3D shape on the right updates live to reflect your dimensions and shrinkage forces.
5. Download Report: Click the "Download Report" button to save a branded PDF with all inputs, results, and the live 3D shape snapshot.
Time-Dependent Shrinkage (ACI 209R):
Effective Strain = Ultimate Rate × (Age / (35 + Age))
Total Shrinkage Length:
Shrinkage = Initial Length × (Effective Strain ÷ 1,000,000)
Volume-to-Surface Ratio (V/S):
V/S = Volume / Exposed Surface Area (Critical for drying shrinkage prediction)
Crack Risk Assessment:
Based on shrinkage per 100 units. Low (< 0.10), Moderate (0.10 – 0.25), High (> 0.25).
Joint Spacing Recommendation:
Spacing = 24 × Thickness, adjusted downward for high shrinkage rates or low humidity.