ISO 17785-2:2018

Overview

ISO 17785-2:2018 - "Testing methods for pervious concrete - Part 2: Density and void content" specifies laboratory and field procedures to determine the density and void content of both freshly mixed and hardened pervious concrete used for pavements. The standard covers sampling, required apparatus, step‑by‑step test procedures, and the formulae for calculating density and void percentage for specimens made in the lab or cored from field placements.

Key topics and technical requirements

• Scope and purpose
  • Measures density (kg/m3) and void content (%) of pervious concrete to verify mixture proportions and permeability-related properties.
• Specimen types
  • Fresh samples consolidated in a cylindrical measure.
  • Hardened specimens: moulded cylinders (nominal 100 mm diameter, height twice diameter) or field cores (minimum 100 mm diameter and 100 mm height).
• Sampling
  • Minimum of three similar specimens per test.
• Apparatus and accuracy
  • Measure (≥150 mm internal dimensions), strike‑off plate, coring machine, non‑reactive moulds.
  • Balance accurate to 0.5 g or 0.3% of load; calipers to 0.25 mm.
  • Oven capable of 50 °C ± 5 °C; water bath and thermometer (±0.5 °C).
• Fresh concrete procedure
  • Two layers placed and consolidated; typical consolidation: 20 hammer drops per layer at 300 mm drop height (hammer ~4.5 kg suggested).
  • Strike off, clean, and weigh measure plus concrete to compute fresh density.
• Hardened concrete procedure
  • Measure dimensions, dry to constant mass (oven at 50 °C ± 5 °C in 24 h increments until mass change < 0.5%).
  • Determine submerged mass after 30 min soak in water at 20 °C ± 2 °C (use rubber mallet tapping to remove trapped air).
• Calculations
  • Standard formulae for fresh and hardened density and for void content, including a theoretical (air‑free) density basis for fresh mixtures.

Applications and users

• Who uses it
  • Pavement engineers, materials laboratories, quality‑control technicians, contractors, and researchers working with pervious concrete.
• Practical uses
  • Verifying batch proportions and compaction methods.
  • Correlating void content with hydraulic performance and structural requirements of pervious pavements.
  • Acceptance testing for field placements and laboratory mix development.

Related standards

• Part of the ISO 17785 series (other parts cover additional pervious concrete test methods).
• Notes reference related test practices (e.g., ISO 1920‑5) for submerged specimen support.

Keywords: ISO 17785-2:2018, pervious concrete testing, density and void content, pervious pavement, fresh and hardened specimens, laboratory testing, core sampling.