The lab team in Chandler operates a dual-stage sieve shaker and a sedimentation hydrometer setup to separate soil fractions from gravel down to clay-sized particles. A representative sample is first oven-dried and weighed, then passed through a nested column of sieves ranging from 3-inch to No. 200 mesh. For the fraction finer than No. 200, the hydrometer method measures particle settling velocity in a controlled water column. This combination provides a complete particle-size distribution curve, essential for classifying soils under the Unified Soil Classification System (USCS). Before finalizing foundation design, many engineers also review the limits of Atterberg to assess plasticity and correlate it with the fines fraction from the analysis.
Accurate grain size distribution is the foundation of soil classification; it directly influences permeability estimates, liquefaction screening, and compaction specifications.
Methodology and scope
Local considerations
A multi-story residential project on Chandler Boulevard encountered unexpectedly high fines content below the proposed mat foundation. The design originally assumed a clean sand based on visual classification alone. Sieve and hydrometer analysis revealed 35% passing No. 200, with a plasticity index of 12, classifying the soil as lean clay (CL). This changed the bearing capacity estimate and required a switch to deep foundations. Without the grain size analysis, the structure risked excessive differential settlement. The lesson is clear: visual logging cannot replace laboratory grading when fines content drives foundation behavior.
Applicable standards
ASTM D422-63(2007): Standard Test Method for Particle-Size Analysis of Soils, ASTM D6913/D6913M-17: Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis, AASHTO T-88: Standard Method of Test for Particle Size Analysis of Soils, ASTM D2487-17: Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
Associated technical services
Standard Sieve Analysis (ASTM D6913)
Full dry and wet sieving for soil fractions retained on No. 200 sieve. Includes washing to remove fines, mechanical sieving, and calculation of cumulative percent passing. Suitable for sands, gravels, and mixed soils used in road base, fill, and concrete aggregate evaluation.
Hydrometer Analysis (ASTM D422)
Sedimentation method for determining the distribution of silt and clay particles finer than 0.075 mm. Includes dispersion treatment, timed readings, and correction for temperature and specific gravity. Essential for projects requiring USCS classification of fine-grained soils or design of earth dams and liners.
Typical parameters
Frequently asked questions
What is the difference between sieve analysis and hydrometer analysis?
Sieve analysis separates particles larger than 0.075 mm (No. 200 sieve) by mechanical shaking through nested sieves. Hydrometer analysis measures particles smaller than 0.075 mm by tracking their settling velocity in a water column over time. Both are needed for a full grain size distribution curve.
How much does grain size analysis cost in Chandler?
The typical cost for a combined sieve and hydrometer analysis in Chandler ranges from US$100 to US$220 per sample. This includes sample preparation, sieving, hydrometer readings, and a final report with gradation curve and USCS classification. Volume discounts may apply for multiple samples from the same project.
How long does the test take, and when do I get results?
Sieve analysis alone can be completed in 1–2 business days. The full hydrometer procedure requires up to 24 hours of sedimentation readings, so the combined test typically takes 3–5 business days. Reports are delivered electronically with the particle-size distribution curve and classification.