Underground Enclosures Material Comparison

Polymer Concrete (PC)

  • Strength & load performance: High compressive strength and engineered for heavy traffic / utility loads; commonly used where road/vehicular loads are expected.
  • Durability / environment: Very good resistance to freeze-thaw, chemicals and UV; non-conductive and typically self-extinguishing.
  • Weight & handling: Heavier than HDPE/fiberglass (but many polymer-concrete products are lighter than traditional concrete); lids can be heavy — plan for access tools or lighter composite lids.
  • Typical uses: Roadways, parking lots, industrial yards, any site requiring high load rating and long life.

Fiberglass-reinforced Polymer (FRP / Fiberglass)

  • Strength & impact: Good strength-to-weight ratio; typically stiffer than HDPE and lighter than polymer concrete. Can be engineered with significant structural capacity.
  • Durability / environment: Outstanding corrosion resistance (no steel reinforcement to corrode), long service life; non-conductive and chemically inert. Surface finish and brittleness under some impacts are considerations.
  • Weight & handling: Moderate weight — easier than PC, heavier than HDPE.
  • Typical uses: Areas needing corrosion resistance with moderate load requirements: coastal, chemical plants, telco campuses.

Modular Fiberglass Composite Handholes

  • Strength & Impact: Strong but light composite material construction
  • Durability / environment: Resistance of entire construction up to ANSI/SCTE-77 Tier 22
  • Weight & handling: Modular design with knock-down delivery and on-site set up. Drill on the top to secure the lid for handhole access.
  • Typical uses: Duct entry provided through the installation of duct holes on-site. Cost saving due to light weight, modular design

HDPE (High-Density Polyethylene)

  • Strength & impact: Good impact resistance and flexibility; excellent for non-traffic or light-traffic installations. Less compressive stiffness than PC — not intended for heavy vehicular loads unless specifically engineered and rated.
  • Durability / environment: Excellent corrosion resistance, very good chemical resistance and lightweight; but can be susceptible to UV degradation if not UV-stabilized and will melt/burn under extreme heat. Some HDPE formulations are recyclable.
  • Weight & handling: Very lightweight — easy to carry and set, faster installation and easier lid access.
  • Typical uses: Residential easements, campus grounds, non-traffic zones, rapid deployments and areas where handling speed is important.

 

Strengths & tradeoffs — decision checklist

  • If the site is roadway or will see routine truck/maintenance vehicle traffic choose Polymer Concrete (or a product specifically Tier-rated for roadway loads). Polymer concrete is widely chosen for load-rated handholes.
  • If you need fastest install, lowest weight, easy access, and the area is pedestrian or light-vehicle only HDPE (verify the product’s load rating for your use).
  • If corrosion resistance and long life are priorities (coastal, chemical exposure) with moderate loads Fiberglass/FRP (or polymer concrete if heavy loads).
  • Security & fire safety: Polymer concrete is generally non-flammable/self-extinguishing; HDPE can burn/melt and emit fumes in extreme fire conditions — consider location & safety codes.
  • Access ergonomics: HDPE and FRP lids are easier to handle; polymer-concrete lids can be heavy — plan for lifting tools or lighter composite lids.