CFB Materials Selection 2 — Questions and Answers
Question 1: Which material is most appropriate for a synthetic turf infill when drainage performance is the top priority?
- Crumb rubber
- Silica sand (Correct answer)
- Cork granules
- Thermoplastic rubber
Correct answer: Silica sand
Silica sand provides the best drainage performance in synthetic turf infill due to its high permeability and consistent particle size.
Question 2: A field builder is selecting base aggregate for a natural grass sports field. Which gradation is most commonly specified?
- Well-graded gravel (GW)
- Poorly-graded sand (SP)
- USGA-spec rootzone mix (Correct answer)
- Crushed limestone screenings
Correct answer: USGA-spec rootzone mix
USGA-spec rootzone mix is the industry standard for natural grass sports fields because it balances drainage, aeration, and turfgrass support.
Question 3: When selecting underlayment padding for synthetic turf, what property directly affects player safety ratings (Gmax)?
- Tensile strength
- UV resistance
- Shock absorption capacity (Correct answer)
- Water vapor permeability
Correct answer: Shock absorption capacity
Shock absorption capacity of the underlayment directly determines the Gmax value, which is the primary measure of head injury risk reduction.
Question 4: Which geotextile type is preferred beneath a permeable base course to prevent subgrade migration?
- Woven polypropylene geotextile
- Nonwoven needle-punched geotextile (Correct answer)
- Geonet drainage composite
- Geomembrane liner
Correct answer: Nonwoven needle-punched geotextile
Nonwoven needle-punched geotextile acts as a separation and filtration layer, preventing fine subgrade particles from migrating into the base course.
Question 5: A Certified Field Builder is comparing polypropylene (PP) and polyethylene (PE) synthetic turf fibers. What is the key advantage of PE fibers?
- Lower cost
- Higher melting point
- Softer feel and better player comfort (Correct answer)
- Greater UV resistance
Correct answer: Softer feel and better player comfort
Polyethylene fibers are softer than polypropylene and provide better player comfort and skin-friendliness upon contact.
Question 6: Which characteristic of recycled crumb rubber infill has raised environmental and health concerns on synthetic turf fields?
- High alkalinity
- Heavy metal and PAH content (Correct answer)
- Excessive moisture retention
- Rapid biological degradation
Correct answer: Heavy metal and PAH content
Recycled crumb rubber can contain polycyclic aromatic hydrocarbons (PAHs) and trace heavy metals from tire manufacturing, which have raised health concerns.
Question 7: What is the primary function of a drainage layer composed of open-graded aggregate beneath a synthetic turf system?
- Provide a level playing surface
- Reduce fiber abrasion
- Allow rapid vertical drainage away from the field (Correct answer)
- Improve fiber tuftbind strength
Correct answer: Allow rapid vertical drainage away from the field
An open-graded aggregate drainage layer allows stormwater to move vertically and laterally away from the field surface, preventing ponding.
CFB Materials Selection 2
Which material is most appropriate for a synthetic turf infill when drainage performance is the top priority?