Permeable Pavement Infiltration Models for Civil Design

ISEF Category: Engineering Technology: Statics and Dynamics

Subcategory: Civil Engineering  ·  Difficulty: Advanced  ·  Setup: School Lab  ·  Time: Full Year

The Hook

A road can act like a sponge, or like a lid. That difference changes flooding, puddles, and how fast stormwater leaves a site. If you can measure how water moves through a pavement sample, you can model a real drainage system, not just guess at it.

What Is It?

Permeable pavement lets water pass through tiny openings instead of sending it straight into runoff. In this project, you would compare concrete pucks with different 3D-printed lattice cores, then measure how fast water infiltrates through each one. Think of each lattice like the skeleton inside a sponge. The shape of that skeleton changes how much empty space water can use and how easily it can move.

Horton and Green-Ampt are two common ways to describe infiltration. Horton treats infiltration rate like something that drops over time as the material gets wet. Green-Ampt treats flow more like a moving wetting front, the boundary where dry material turns wet. If your data fit one model better than the other, that tells you something about how the pavement is acting.

Why This Is a Good Topic

This is a strong science fair topic because you can change one design feature at a time, measure a real engineering outcome, and compare your results with established models. It connects directly to flooding, stormwater design, and more resilient streets and parking lots. You can learn how to build controls, collect repeatable data, fit curves, and judge which model describes your samples best.

Research Questions

• How does lattice cell size affect infiltration rate in concrete pucks?
• What is the effect of lattice porosity on the time needed for a puck to reach steady infiltration?
• Does lattice orientation change runoff volume under the same simulated storm load?
• To what extent does sample thickness alter the fit quality of Horton and Green-Ampt models?
• Which lattice geometry gives the best balance of fast infiltration and structural mass?
• How does repeated wetting change infiltration performance across test cycles?
• What is the effect of aggregate size around the lattice core on measured infiltration rate?

Basic Materials

• Cured concrete pucks with embedded 3D-printed lattice cores.
• 3D printer and printable polymer filament.
• Digital kitchen scale with 0.1 g accuracy.
• Calibrated garden hose or adjustable spray nozzle.
• Catch basin or tray to collect runoff.
• Measuring jug or graduated container.
• Stopwatch.
• Ruler or calipers.
• Waterproof marker for labeling samples.
• Notebook or data table for recording mass and runoff.
• Absorbent towels for resetting samples between trials.

Advanced Materials

• Universal testing machine for strength comparison.
• Permeameter or flow collection manifold.
• High-precision load cell or lab balance.
• Laser scanner or 3D scanner for pore geometry checks.
• Sieves for aggregate size grading.
• Moisture meter for pretest saturation checks.
• Pressure transducer for head-loss measurements.
• Image analysis setup for porosity and void mapping.
• Environmental chamber for controlled drying between cycles.

Software & Tools

• Excel: Organizes trial data, calculates infiltration rates, and plots model fits.
• Google Sheets: Tracks repeated trials and compares sample groups with simple formulas.
• Python: Fits Horton and Green-Ampt curves and tests which model matches best.
• ImageJ: Measures lattice openings and estimates porosity from photos or scans.
• GeoGebra: Helps you visualize curve shape and compare model behavior.

Experiment Steps

1. Define the design variable you will change first, such as lattice cell size, orientation, or porosity.
2. Choose the response you will measure, such as infiltration rate, runoff mass, or model fit error.
3. Plan a control sample that lets you compare your lattice core against a plain concrete puck.
4. Design a repeatable storm simulation and decide how you will keep the water input consistent across trials.
5. Build a data sheet that links each sample geometry to every mass, flow, and timing measurement.
6. Decide how you will fit your data to Horton and Green-Ampt models and compare the residuals.

Common Pitfalls

• Letting the hose spray pattern change between trials, which changes the water input and makes samples hard to compare.
• Using pucks that dry to different starting moisture levels, which skews infiltration results from the first minute.
• Printing lattice cores with small geometry errors, which means the samples no longer match your design plan.
• Measuring runoff without accounting for splash loss, which makes infiltration seem higher than it really is.
• Fitting models to only one trial per sample, which hides how much random variation your setup has.

What Makes This Competitive

A competitive project would do more than compare a few samples. You would need tight controls, enough repeats to support statistics, and a clear reason why one geometry should work better than another. Strong entries often test model fit, not just raw infiltration, then explain why Horton or Green-Ampt matches the physics better. You could also add a structural tradeoff, so the best drainage design is not just the fastest one.

Project Variations

• Test lattice cores with different void fractions to see how porosity changes infiltration and model fit.
• Compare rectangular, hexagonal, and gyroid lattice shapes to see which geometry drains fastest.
• Add repeated wet-dry cycles to study how clogging or surface sealing changes performance over time.

Learn More

• USGS Water Science School: Search the USGS site for pages on infiltration, runoff, and stormwater concepts.
• NOAA Atlas 14: Find rainfall frequency and storm intensity data for your region on the NOAA site.
• FHWA Stormwater and Pavement Resources: Search the Federal Highway Administration site for permeable pavement guides and design notes.
• ASCE Library: Search peer-reviewed civil engineering papers on permeable pavements, infiltration, and stormwater modeling.
• MIT OpenCourseWare Civil and Environmental Engineering: Look for open lecture notes on fluid flow, drainage, and hydrology.
• PubMed: Search for review articles on urban stormwater control and permeable pavement performance.