{
  "name": "PondLock sodium bentonite material specification",
  "description": "Material requirements for natural sodium bentonite used as a soil amendment in compacted soil liners for ponds, lakes, and earthen dams.",
  "url": "https://pond-lock.com/engineering-resources#liner-specification",
  "product": "PondLock granular sodium bentonite",
  "publisher": "Natural Waterscapes",
  "last_updated": "2026-09-05",
  "bentonite_type": {
    "requirement": "Natural sodium bentonite (sodium montmorillonite)",
    "pondlock": "Wyoming sodium bentonite",
    "excluded": [
      "Calcium bentonite",
      "Blended products",
      "Chemically treated clays"
    ]
  },
  "properties": [
    {
      "property": "Free Swell Index",
      "requirement": "≥ 22 ml (≥ 25 ml preferred)",
      "requirement_value": 22,
      "unit": "ml",
      "test_method": "ASTM D5890",
      "pondlock_value": 30,
      "pondlock": "30 ml",
      "compliant": true,
      "margin_over_requirement_pct": 36
    },
    {
      "property": "Moisture Content",
      "requirement": "≤ 20%",
      "requirement_value": 20,
      "unit": "%",
      "test_method": "At delivery",
      "pondlock": "Sun-dried",
      "compliant": true
    },
    {
      "property": "pH Range",
      "requirement": "7.5 – 8.7",
      "unit": "pH",
      "test_method": "Typical",
      "compliant": true
    },
    {
      "property": "Expansion Capacity",
      "requirement": "~15X dry volume (unconfined)",
      "requirement_value": 15,
      "unit": "x dry volume",
      "test_method": "Visual / Lab",
      "pondlock": "~15X dry volume",
      "compliant": true
    },
    {
      "property": "Aged Viscosity",
      "requirement": "≥ 30 (Fann 600 rpm)",
      "requirement_value": 30,
      "unit": "Fann 600 rpm",
      "test_method": "Per manufacturer",
      "compliant": true
    },
    {
      "property": "Physical Form",
      "requirement": "Granular, suitable for field mixing",
      "test_method": "Sieve analysis",
      "pondlock": "Granular (–8 mesh)",
      "compliant": true
    },
    {
      "property": "Additives",
      "requirement": "None",
      "pondlock": "None",
      "compliant": true
    }
  ],
  "gradation": {
    "requirement": "100% passing No. 8 sieve (2.36 mm); maximum 12% passing No. 200 sieve (75 µm)",
    "passing_no8_pct": 100,
    "max_passing_no200_pct": 12,
    "rationale": [
      "Reduce wind-borne dust",
      "Improve worker safety",
      "Enhance field constructability",
      "Promote uniform soil blending",
      "Reduce material loss during placement"
    ],
    "note": "Material shall not be predominantly powder-grade or slurry-oriented in form."
  },
  "comparison": {
    "test_method": "ASTM D5890",
    "results": [
      {
        "material": "PondLock (Wyoming sodium bentonite)",
        "free_swell_index_ml": 30,
        "meets_nrcs_cps_520": true
      },
      {
        "material": "Typical Texas-sourced bentonite",
        "free_swell_index_ml": 12,
        "meets_nrcs_cps_520": false
      }
    ],
    "nrcs_cps_520_minimum_ml": 22
  }
}