ASTM D3385-18 is a standardized field test method published by ASTM International (formerly known as the American Society for Testing and Materials). The full title is:
Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer astm d338518 pdf
The double-ring infiltrometer is the core apparatus. It consists of two concentric metal rings driven into the soil. Water is maintained at a constant level in both rings. The inner ring measures the vertical infiltration rate, while the outer ring creates a buffer zone to minimize lateral spread of water, ensuring that flow in the inner ring is predominantly one-dimensional (vertical). ASTM D3385-18 is a standardized field test method
To get the details directly from the source: Standard Test Method for Infiltration Rate of Soils
The ASTM D3385-18 standard provides a detailed methodology for determining the pore size distribution of geotextiles by the dry sieving method. This method involves passing dry soil particles of known sizes through the geotextile sample and measuring the percentage of particles that pass through. The standard outlines the equipment requirements, sample preparation procedures, and testing protocols to ensure consistency and accuracy across different laboratories and testing conditions.