Standard Proctor Cylindrical Compaction Mold
Machined steel mold (101.6 mm internal diameter, 116.4 mm height, volume 944 cm³) with detachable collar and baseplate.
Civil Engineering / Standard Proctor Compaction
FREE TO EXPLORELABORATORY 19 · CIVIL ENGINEERING
Soil Moisture-Density Relationship & Optimum Moisture Content (Standard Proctor Test)
Determine the relationship between moisture content and dry density of compacted soil, establish the maximum dry density (MDD), and identify the optimum moisture content (OMC) according to ASTM D698 / AASHTO T99. Explore interactive structural mechanics, materials simulation, and civil engineering telemetry.
STRUCTURAL MATERIALS · MECHANICS · GEOTECHNICAL · HYDRAULICS · HIGHWAYS · SURVEYING
Your virtual civil engineering laboratory.
COMPACTED DRY DENSITY Ρ_D—
CIVIL INFRASTRUCTURE TELEMETRY
Ready to sample with Moisture w = 14.0 %.
Adjust Moisture w, then execute civil engineering measurement.
Civil engineering telemetry is evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity structural mechanics and geotechnical continuum modeling.
Civil engineering assumptions and boundary condition limits
The civil engineering physical models apply within the specified calibrated operational window (8.0 to 20.0 %). Evaluated on silty clay subgrade soil (CL under USCS). Linearized representation over the compaction moisture interval relates dry density metric directly to moisture content w with sensitivity 0.0380 g/(cm³·%).
Laboratory apparatus & testing equipment.
Standard Mechanical Compaction Rammer
2.495 kg (5.5 lbf) sliding drop hammer with 50.8 mm circular face and 304.8 mm controlled drop sleeve.
Steel Straightedge Strike-Off Bar
Machined rigid steel bar with beveled edge for screeding compacted soil flush with mold rim.
Electric Thermostatic Drying Oven
Maintains 110 ± 5 °C for 24 hours to determine gravimetric soil moisture content.
Electronic High-Capacity Precision Balance
Measures mold and moist compacted soil mass to 1.0 g resolution (capacity 20 kg).
Hydraulic Soil Specimen Extruder
Smoothly extrudes compacted soil core from mold without damaging specimen structure.
FOLLOW THE METHOD
A reason behind every step.
Determine the relationship between moisture content and dry density of compacted soil, establish the maximum dry density (MDD), and identify the optimum moisture content (OMC) according to ASTM D698 / AASHTO T99. Standardized parameter settings: 8.0, 10.0, 12.0, 14.0, 16.0, 18.0, 20.0 %.
01
Soil Preparation & Initial Moisture Dosing
Air-dry 15 kg of subgrade soil passing the 4.75 mm (No. 4) sieve; split into 2.5 kg batches; mix initial batch with target moisture content (e.g. 8.0%); seal in plastic bag for 16 hours to equilibrate.
02
Mold Assembly & Tare Weighing
Clean and weigh empty Proctor mold with baseplate (without collar) to the nearest 1.0 g; record mass M_mold; attach collar securely.
03
Three-Layer Standard Compaction
Place soil into mold in three approximately equal layers; compact each layer with exactly 25 uniform blows of the 2.495 kg rammer dropping from 304.8 mm.
04
Collar Removal & Surface Screeding
Carefully remove collar; trim excess soil projecting above top of mold flush with straightedge using sawing motions; patch minor surface voids with fines.
05
Mold Weighing & Moist Density Calculation
Clean exterior of mold and baseplate; weigh mold with moist soil to nearest 1.0 g (M_total); calculate wet density ρ_wet = (M_total - M_mold) / 944 cm³.
06
Moisture Content Determination & Curve Plotting
Extrude soil core; extract moisture samples from top, middle, and bottom; dry in oven at 110 °C to determine w; calculate ρ_d = ρ_wet / (1 + w); repeat at 10%, 12%, 14%, 16%, 18%, and 20% to plot the compaction curve.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into civil engineering insight.
Points are your recorded observations. The solid regression line validates Standard Proctor Compaction mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
ρ_d = 0.0380 · w
| # | Moisture Deviation Parameter w (%) | Compacted Dry Density ρ_d (g/cm³) | Moisture content parameter w (%) | Dry density metric (g/cm³) | Remove |
|---|
No readings yet. Execute a civil engineering trial and record it.
Calculate it yourself.
CHECK YOUR UNDERSTANDING
Explain what the civil engineering metrics mean.
The mechanical compaction energy applied in the Standard Proctor test (ASTM D698) is approximately:
The mass of the rammer and height of drop in the Standard Proctor test are:
Increasing compaction effort on a given soil produces:
The Zero Air Voids line on a compaction plot corresponds to an air voids content of:
THEORY AND STRUCTURAL CONTEXT
Civil engineering background & physical principles.
In geotechnical earthworks—including highway embankments, earth dams, airport subgrades, and structural foundation pads—soil must be mechanically compacted to densify its particulate matrix, increase shear strength, reduce hydraulic conductivity (permeability), and minimize post-construction settlement. Developed by Ralph R. Proctor in 1933, the Standard Proctor Compaction test (ASTM D698) standardizes mechanical compaction effort at 592 kJ/m³ (12,375 ft-lbf/ft³). A soil sample prepared at a known moisture content is compacted in three equal layers into a cylindrical steel mold (101.6 mm diameter, 116.4 mm height, volume 944 cm³) using 25 blows per layer of a 2.495 kg (5.5 lbf) mechanical rammer dropping freely from a height of 304.8 mm (12 inches). Wet density ρ_wet is determined from the mold mass, and moisture content w is measured by oven drying to compute dry density: ρ_d = ρ_wet / (1 + w). Plotting dry density against moisture content yields a classic bell-shaped compaction curve peaking at Maximum Dry Density (MDD) and Optimum Moisture Content (OMC). At low moisture ('dry of optimum'), soil particles are rigid and resist rearrangement; added water forms lubricating double-layer films allowing particles to pack densely. Beyond OMC ('wet of optimum'), incompressible water fills the pore space, displacing soil solids and lowering dry density toward the Zero Air Voids (ZAV) theoretical saturation limit. In this laboratory, the compaction response is evaluated across moisture levels from 8% to 20% to calibrate density sensitivity.
ρ_d = 0.0380 · w
Evaluated on silty clay subgrade soil (CL under USCS). Linearized representation over the compaction moisture interval relates dry density metric directly to moisture content w with sensitivity 0.0380 g/(cm³·%).