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Grain Size Analysis (Sieve & Hydrometer) for St. John's, NL

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Overlooking the fines content in a glacial till can delay a St. John's foundation pour by weeks. Many contractors assume a visual classification is enough, but the silty matrix common across the Avalon Peninsula behaves very differently under freeze-thaw cycles than a clean sand. Our laboratory runs the full grain size analysis—sieve plus hydrometer—to quantify exactly that silt and clay fraction. The combined curve from 75 mm down to 0.001 mm reveals the soil's real drainage potential and frost susceptibility, parameters directly tied to the NBCC requirements for footing depth. When a site on Kenmount Road hits a pocket of marine clay, knowing the particle-size distribution before ordering concrete saves rework. We often pair this with Atterberg limits to confirm plasticity, and with test pits to correlate lab data with field stratigraphy.

A soil with 12% fines and a uniformity coefficient below 3 will pump water under traffic load—the grain size curve tells that story before the first truck arrives.

Our service areas

How we work

In St. John's, the difference between a well-graded till and a gap-graded outwash can decide whether a stormwater infiltration trench works or clogs after the first November rain. The sieve stack separates gravel and sand fractions with precision, while the hydrometer settles silt and clay in a controlled column over 24 hours, following ASTM D7928 for fine-grained materials. A single report gives you D10, D30, D60, the uniformity coefficient, and the coefficient of curvature—numbers that directly feed into filter design for retaining structures. We see a lot of crushed stone coming from quarries near Torbay Road; verifying its gradation against CSA A23.3 specifications is a routine but essential QA step. For coastal projects exposed to salt-laden wind, the particle surface area derived from the hydrometer test also helps estimate the reactivity of potential aggregate sources. Our technicians run dispersant blanks daily to cancel out water-temperature drift, a small calibration detail that keeps the silt curve accurate even when the lab drops to 16°C in winter.
Grain Size Analysis (Sieve & Hydrometer) for St. John's, NL
Technical reference — St. Johns Newfoundland

Local geotechnical context

A set of 8-inch brass sieves sits on a Ro-Tap shaker inside our St. John's lab, and the hydrometer cylinders float in a thermostatically controlled water bath. The biggest risk in a grain size analysis isn't the equipment—it's the sample preparation. A field sample from a Water Street excavation that arrives with lumps of dried clay must be gently disaggregated with a rubber-tipped pestle, never crushed, or the sand fraction gets artificially inflated. Skipping the wash-over-No.200 step introduces errors up to 15% in the fines content, a mistake that cascades into an incorrect USCS classification and a thinner aggregate base than the NBCC expects. For hydrometer readings, a one-degree temperature shift without a proper blank correction skews the silt-versus-clay boundary. The Canadian Foundation Engineering Manual warns that frost heave potential is controlled by the percentage finer than 0.02 mm—miss that threshold and a St. John's parking lot becomes a springtime liability.

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Explanatory video

Relevant standards

ASTM D6913 – Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis, ASTM D7928 – Standard Test Method for Particle-Size Distribution (Gradation) of Fine-Grained Soils Using the Sedimentation (Hydrometer) Analysis, CSA A23.2-2A – Sieve analysis of fine and coarse aggregates, NBCC 2020, Division B, Section 9.12 – Depth of footings and frost protection considerations, ASTM D2487 – Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)

Typical values

ParameterTypical value
Test standardsASTM D6913, ASTM D7928, CSA A23.2-2A
Sieve range75 mm (3 in) down to 0.075 mm (No. 200)
Hydrometer range0.075 mm down to 0.001 mm
Key outputsGradation curve, D10, D30, D60, Cu, Cc, % gravel/sand/silt/clay
Sample mass required500 g for sands, 200 g for silts/clays (dry)
Dispersing agentSodium hexametaphosphate, blank corrected per ASTM D7928
Report formatSemi-log plot with tabulated passing percentages and USCS classification
Typical turnaround3–5 business days from sample receipt

Questions and answers

How much does a grain size analysis (sieve + hydrometer) cost in St. John's?

For projects in the St. John's area, a combined sieve and hydrometer analysis typically runs between CA$160 and CA$220 per sample. The final figure depends on whether the material is a clean sand—requiring only a dry sieve stack—or a silty soil that needs the full wash procedure plus a 24-hour hydrometer sedimentation. We provide a firm quote once we see the sample condition and know the number of specimens.

What sample mass do you need for the hydrometer test?

We ask for a representative dry mass of about 200 grams of material passing the No. 10 sieve for the hydrometer portion. For the full combined analysis, sending a one-gallon bag of bulk soil lets us run the sieve stack on the coarse fraction and split off enough fines for sedimentation, following the specimen preparation protocols in ASTM D7928.

Can you classify the soil from just the grain size curve?

The gradation curve gives us the percentages of gravel, sand, and fines, which gets us most of the way to a USCS classification per ASTM D2487. For silts and clays, we also need the Atterberg limits to distinguish between ML, CL, MH, and CH soils. We recommend running both tests together on any St. John's sample with more than 12% passing the No. 200 sieve.

Why does the hydrometer test take longer than the sieve analysis?

The hydrometer method measures how fast particles settle through a water column, and the smallest clay platelets—those below 0.002 mm—can take over 24 hours to drop just a few centimeters. Readings are taken at precise time intervals over that full period, with temperature corrections applied at each step, so the test cannot be rushed without compromising the accuracy of the silt and clay fractions.

Location and service area

We serve projects in St. Johns Newfoundland and surrounding areas.

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