PTI Unbonded Installer & Inspector Certification Exam |
Complete Practice Questions & Detailed Rationales 2026/2027
Question 1
What is the primary function of the heavy-duty plastic sheathing and
corrosion-inhibiting grease on an unbonded single-strand post-
tensioning tendon?
• A. To permanently bond the steel strand to the surrounding
concrete matrix.
• B. To provide long-term corrosion protection and allow the strand
to slide (elongate) freely inside the concrete without bonding.
• C. To conduct electrical grounding current through the floor slab.
• D. To heat the concrete during winter placements.
Correct Answer: B. To provide long-term corrosion protection and allow
the strand to slide (elongate) freely inside the concrete without
bonding.
Detailed Rationale: Unbonded systems rely on grease and tight
sheathing to prevent moisture corrosion while ensuring that tensioning
forces are transferred exclusively at the anchorages rather than along
the length of the strand.
Question 2
What standard ASTM specification governs uncoated seven-wire steel
strand used for prestressed and post-tensioned concrete?
• A. ASTM A416
, • B. ASTM A36
• C. ASTM A615
• D. ASTM A82
Correct Answer: A. ASTM A416
Detailed Rationale: ASTM A416 specifies the mechanical properties,
tensile strengths, and manufacturing standards for high-strength seven-
wire steel strands used in post-tensioning.
Question 3
What is the minimum weight of moisture-displacing, corrosion-
inhibiting grease required per 100 feet of 0.5-inch unbonded post-
tensioning strand under PTI specifications?
• A. At least 2.5 wet pounds per 100 feet.
• B. Exactly 50 pounds per 100 feet.
• C. Zero pounds, as grease is optional.
• D. 0.05 ounces per 100 feet.
Correct Answer: A. At least 2.5 wet pounds per 100 feet.
Detailed Rationale: PTI guidelines mandate a minimum specified mass
of grease to ensure a continuous, lifelong protective film inside the
plastic sheathing.
Question 4
How should unbonded post-tensioning strand coils be stored at a
construction site prior to installation?
• A. Stored directly on bare wet soil or muddy ground.
, • B. Elevated off the ground on dunnage and covered securely to
protect against moisture, dirt, and corrosive job-site chemicals.
• C. Submerged in standing water to keep them cool.
• D. Left uncoiled across heavy equipment traffic lanes.
Correct Answer: B. Elevated off the ground on dunnage and covered
securely to protect against moisture, dirt, and corrosive job-site
chemicals.
Detailed Rationale: Proper storage prevents pitting corrosion and
contamination that can cause premature failure of high-strength
prestressing steel.
Question 5
What action must be taken if unbonded post-tensioning strand exhibits
deep pitting or heavy rust upon delivery?
• A. Paint over the rust with latex house paint.
• B. Reject the material and remove it from the site per PTI and
ASTM inspection criteria.
• C. Use it exclusively for bottom slab reinforcement.
• D. Heat the strand with a torch to burn the rust off.
Correct Answer: B. Reject the material and remove it from the site per
PTI and ASTM inspection criteria.
Detailed Rationale: Pitting reduces the effective cross-sectional area
and creates severe stress concentration points that compromise strand
integrity.
Question 6
, What is the function of intermediate support chairs during unbonded
post-tensioning installation?
• A. To provide seating for workers during meal breaks.
• B. To support tendons at exact vertical elevations and profiles
along the span.
• C. To anchor plumbing vent pipes to the formwork.
• D. To store hydraulic oil containers.
Correct Answer: B. To support tendons at exact vertical elevations and
profiles along the span.
Detailed Rationale: Chairs maintain correct drape and parabolic
geometry, ensuring the slab achieves its designed structural load
capacity.
Question 7
What is the typical vertical placement tolerance for support chairs
holding tendons in place before concrete placement?
• A. Within plus or minus 1/4 inch of the specified profile.
• B. Plus or minus 5 inches.
• C. Vertical placement does not matter.
• D. Exactly plus or minus 3 feet.
Correct Answer: A. Within plus or minus 1/4 inch of the specified
profile.
Complete Practice Questions & Detailed Rationales 2026/2027
Question 1
What is the primary function of the heavy-duty plastic sheathing and
corrosion-inhibiting grease on an unbonded single-strand post-
tensioning tendon?
• A. To permanently bond the steel strand to the surrounding
concrete matrix.
• B. To provide long-term corrosion protection and allow the strand
to slide (elongate) freely inside the concrete without bonding.
• C. To conduct electrical grounding current through the floor slab.
• D. To heat the concrete during winter placements.
Correct Answer: B. To provide long-term corrosion protection and allow
the strand to slide (elongate) freely inside the concrete without
bonding.
Detailed Rationale: Unbonded systems rely on grease and tight
sheathing to prevent moisture corrosion while ensuring that tensioning
forces are transferred exclusively at the anchorages rather than along
the length of the strand.
Question 2
What standard ASTM specification governs uncoated seven-wire steel
strand used for prestressed and post-tensioned concrete?
• A. ASTM A416
, • B. ASTM A36
• C. ASTM A615
• D. ASTM A82
Correct Answer: A. ASTM A416
Detailed Rationale: ASTM A416 specifies the mechanical properties,
tensile strengths, and manufacturing standards for high-strength seven-
wire steel strands used in post-tensioning.
Question 3
What is the minimum weight of moisture-displacing, corrosion-
inhibiting grease required per 100 feet of 0.5-inch unbonded post-
tensioning strand under PTI specifications?
• A. At least 2.5 wet pounds per 100 feet.
• B. Exactly 50 pounds per 100 feet.
• C. Zero pounds, as grease is optional.
• D. 0.05 ounces per 100 feet.
Correct Answer: A. At least 2.5 wet pounds per 100 feet.
Detailed Rationale: PTI guidelines mandate a minimum specified mass
of grease to ensure a continuous, lifelong protective film inside the
plastic sheathing.
Question 4
How should unbonded post-tensioning strand coils be stored at a
construction site prior to installation?
• A. Stored directly on bare wet soil or muddy ground.
, • B. Elevated off the ground on dunnage and covered securely to
protect against moisture, dirt, and corrosive job-site chemicals.
• C. Submerged in standing water to keep them cool.
• D. Left uncoiled across heavy equipment traffic lanes.
Correct Answer: B. Elevated off the ground on dunnage and covered
securely to protect against moisture, dirt, and corrosive job-site
chemicals.
Detailed Rationale: Proper storage prevents pitting corrosion and
contamination that can cause premature failure of high-strength
prestressing steel.
Question 5
What action must be taken if unbonded post-tensioning strand exhibits
deep pitting or heavy rust upon delivery?
• A. Paint over the rust with latex house paint.
• B. Reject the material and remove it from the site per PTI and
ASTM inspection criteria.
• C. Use it exclusively for bottom slab reinforcement.
• D. Heat the strand with a torch to burn the rust off.
Correct Answer: B. Reject the material and remove it from the site per
PTI and ASTM inspection criteria.
Detailed Rationale: Pitting reduces the effective cross-sectional area
and creates severe stress concentration points that compromise strand
integrity.
Question 6
, What is the function of intermediate support chairs during unbonded
post-tensioning installation?
• A. To provide seating for workers during meal breaks.
• B. To support tendons at exact vertical elevations and profiles
along the span.
• C. To anchor plumbing vent pipes to the formwork.
• D. To store hydraulic oil containers.
Correct Answer: B. To support tendons at exact vertical elevations and
profiles along the span.
Detailed Rationale: Chairs maintain correct drape and parabolic
geometry, ensuring the slab achieves its designed structural load
capacity.
Question 7
What is the typical vertical placement tolerance for support chairs
holding tendons in place before concrete placement?
• A. Within plus or minus 1/4 inch of the specified profile.
• B. Plus or minus 5 inches.
• C. Vertical placement does not matter.
• D. Exactly plus or minus 3 feet.
Correct Answer: A. Within plus or minus 1/4 inch of the specified
profile.
