Calculator Inputs
Formula Used
- L is crack length in meters.
- W is average crack width in millimeters.
- D is injection depth in millimeters.
- F_void covers roughness and hidden voids.
- Waste is a percentage allowance.
- F_expand is foam expansion factor (≥1).
- η is injection efficiency (0–1).
Port count per segment is estimated as ceil(L_mm / spacing_mm) + 1. Always validate against the project method statement and site conditions.
How to Use This Calculator
- Measure each crack run and split it into practical segments.
- For every segment, enter average width and injection depth.
- Select crack condition, then adjust expansion and efficiency as needed.
- Set waste and void factor to reflect surface roughness and losses.
- Enter kit or cartridge sizes to match your supply packaging.
- Press Calculate to view results above the form.
- Download CSV or PDF to attach to inspections and QA records.
Example Data Table
| Example | Length (m) | Width (mm) | Depth (mm) | Void Factor | Waste (%) | Expansion | Efficiency | Typical Output (Liquid L) |
|---|---|---|---|---|---|---|---|---|
| Dry structural crack | 3.0 | 1.0 | 30 | 1.15 | 10 | 1.0 | 0.90 | ≈ 0.13 |
| Wet/leaking crack | 2.0 | 1.5 | 40 | 1.25 | 15 | 8.0 | 0.80 | ≈ 0.02 |
| Moving joint (tighter ports) | 4.0 | 2.0 | 25 | 1.20 | 12 | 1.0 | 0.85 | ≈ 0.33 |
Example outputs are indicative and depend on crack geometry and selected yield settings.
Material Estimation Inputs
Enter crack length in meters, plus average width and injection depth in millimeters. The calculator converts length to millimeters, multiplies L×W×D, then divides by 1,000,000 to obtain liters of void volume. A void factor (typically 1.05–1.35) increases volume for rough walls, branching microcracks, and hidden cavities. Waste allowance (often 8–20%) covers priming the pump, flushing lines, and small leaks at ports.
Crack Segmentation Strategy
Segmenting improves accuracy when width or depth changes along a run. Split long cracks at corners, changes in thickness, or visible widening, and keep each segment reasonably uniform. For slabs and walls, 1–3 m segments often match practical injection staging and make checking measurements easier. Summed segment volumes provide a transparent audit trail in the results table, helping supervisors validate inputs before ordering material.
Yield, Expansion, and Efficiency
Liquid resin demand is reduced by foam expansion, but only where water-reactive grades are appropriate. Use expansion 1.0 for non-foaming structural injection and 5–15 for water-reactive foaming systems. Efficiency (0.75–0.90 common) accounts for backflow, hose retention, and incomplete fill near exits or unsealed faces. Density (commonly 0.9–1.2 kg/L) converts liters to mass for logistics and lift planning.
Ports, Spacing, and Accessories
Port count is estimated as ceil(Lmm/spacing)+1. Typical spacing is 150–300 mm; tighter spacing improves reach in moving cracks and heavily reinforced sections. Add spares (5–15%) for damaged packers, blocked ports, and re-injection after curing. Accessories may include surface sealant, flush solvent, injection nipples, caps, and temporary clamps for crack face support.
Reporting and Quality Control
Use the CSV or PDF export to store assumptions, calculated liters, and packaging quantities. Kit and cartridge rounding helps prevent shortages: the calculator rounds up to full kits and whole cartridges based on your packaging sizes. Record resin batch numbers, ambient temperature, and injection pressures alongside the report for QA. Compare calculated liquid liters to actual consumption to refine waste and void factors on future jobs, improving cost control, scheduling confidence, and material planning overall for teams.
FAQs
What expansion factor should I use?
Use 1.0 for non-foaming structural injection. For water-reactive foaming PU on active leaks, start around 5–10 and adjust based on manufacturer data, temperature, and observed rebound at the crack.
How do I choose injection depth?
Use the effective thickness you plan to fill, typically the member thickness minus cover you will not inject. If the crack does not run full depth, use core data, scans, or conservative partial depth estimates.
Why is efficiency set below 1.0?
Not all pumped resin becomes in-crack volume. Losses occur from line priming, backflow at ports, minor face leakage, and resin remaining in hoses or mixers. Efficiency helps keep ordering realistic.
How is port count calculated?
The calculator estimates ports as ceil(length in mm ÷ spacing) + 1 for each segment. This provides one port at the start and end, plus intermediate ports to maintain reach.
Can I estimate cost in this tool?
Yes. Choose pricing per kit or per liter, then enter your unit price. The calculator applies your selection to the rounded kit count or computed liquid liters to produce an estimated material cost.
Should surface sealant volume be included?
No. This calculator focuses on injection resin. Sealant, paste, and patching materials vary by method and surface roughness. Track them separately or add a dedicated allowance to your project estimate.