CTI CTI Grout & Mortar Systems 2 — Questions and Answers
Question 1: Which setting mortar has a peanut-butter consistency and is applied with a notched trowel to create bonding ridges?
- Dry-pack mortar
- Medium-bed mortar
- Thinset mortar (Correct answer)
- Thick-bed mortar
Correct answer: Thinset mortar
Thinset mortar has a wet, spreadable consistency applied with a notched trowel; the ridges collapse when tile is pressed in, maximizing contact.
Question 2: ANSI A118.4 specifies performance requirements for which type of tile setting mortar?
- Standard dry-set Portland cement thinset
- Latex-Portland cement (polymer-modified) mortar (Correct answer)
- Two-component epoxy adhesive
- Organic mastic adhesive
Correct answer: Latex-Portland cement (polymer-modified) mortar
ANSI A118.4 specifies requirements for latex-Portland cement (polymer-modified) mortar, offering improved bond strength and flexibility over standard thinset.
Question 3: When inspecting large-format tile (24"×24" or larger) installations, what technique should a CTI inspector verify was used to achieve proper coverage?
- Standard V-notch trowel without back-buttering
- Large-format mortar with back-buttering of tile back (Correct answer)
- Organic mastic applied directly to tile backs
- Epoxy grout used as both adhesive and grout
Correct answer: Large-format mortar with back-buttering of tile back
Large-format tiles require medium-bed mortar and back-buttering to achieve the minimum 95% mortar contact coverage required by TCNA.
Question 4: What minimum mortar contact coverage does TCNA require for tile installations in wet areas such as showers?
- 80%
- 85%
- 95% (Correct answer)
- 100%
Correct answer: 95%
TCNA requires 95% mortar contact coverage in wet areas and exterior installations to prevent water infiltration and ensure structural integrity.
Question 5: What product is the standard recommendation for removing dried cement grout haze from tile surfaces?
- Muriatic acid solution
- Sulfamic acid-based cleaner (Correct answer)
- Household bleach solution
- Mechanical power sanding
Correct answer: Sulfamic acid-based cleaner
Sulfamic acid cleaners dissolve dried cement grout haze without the aggressive strength of muriatic acid, making them safe for most tile surfaces.
Question 6: What does a medium-bed mortar offer that standard thinset mortar cannot provide?
- Faster cure time for same-day grouting
- Application thickness up to 3/4 inch without slumping or shrinking (Correct answer)
- Permanent flexibility after full cure
- Water resistance without polymer additives
Correct answer: Application thickness up to 3/4 inch without slumping or shrinking
Medium-bed mortars contain anti-slump additives allowing greater application depths up to 3/4 inch to accommodate substrate variation under large tiles.
CTI CTI Grout & Mortar Systems 2
Which setting mortar has a peanut-butter consistency and is applied with a notched trowel to create bonding ridges?