Leveling and Finishing Portland Cement Mortar

03 01 00 | No. 737 | Print Version | Safety Data Sheet | Sustainability Letter


GEM-PLAST TC is a one-component, polymer-modified, high performance, Portland-based mortar used for leveling of surfaces before application of waterproofing coatings.


GEM-PLAST TC is used for interior and exterior applications over concrete and masonry. It is suitable for cisterns, reservoirs, wastewater containment facilities, swimming pools, and above- and below-grade walls and floors, including cold storage rooms and food processing plants.


  • Self-curing
  • Highly crack resistant
  • Tough and durable
  • Excellent bond
  • Can be featheredged
  • Easy to clean
  • Superior freeze/thaw resistance
  • Non-flammable
  • Non-toxic
  • Breathable
  • Excellent workability/Easy application


50 Lb. (22.7 kg) Bags


0.44 ft.3 (12.5 L)

Covers approximately 42.4 ft.2 @ 1/8″ (4.2 m2 @ 3 mm) thickness per bag.


When stored on pallets in a dry, cool area, shelf life is 12 months.


Modulus of Rupture
(ASTM C438)
800 – 100 psi
(5.5 – 6.9 MPa)
Compressive Strength
(ASTM C109 Modified)
5000 – 5500 psi
(34.5 – 37.9 MPa)
Freeze-Thaw Resistance
(ASTM C666, Procedure A)
Weight Loss <1%
Available Colors Industrial Gray, White

Surface Preparation …  Remove all loose particles, dirt, oil, grease, form release agents, laitance, efflorescence. and any other bond inhibiting materials by wet or dry sand blasting or high-pressure water blast [min. 5,000 psi (35 MPa)]. The substrate must be saturated surface damp and free of any standing water prior to subsequent membrane or coating application.

Crack Treatment … Any existing cracks must be treated separately.

Mixing … Mix GEM-PLAST TC with 1.3 gal. (5.0 L) of water, using paddle or helix mortar mixer, or heavy duty (400 – 600 rpm) drill with a suitable mixing paddle. Gradually add dry powder into water, while mixing, and mix until the mix is smooth and lump-free.

Adjust the water for the desirable consistency for brush application, or a little stiffer consistency for trowel application. Do not exceed 1.4 gal. (5.2 L) per bag. Do not overmix.

Application Method … Apply GEM-PLAST TC by trowel to a uniform specified 1/8″ – 1/4″ (3 – 6.35 mm) thickness. If spraying, use a trowel to remove any air and obtain full contact throughout.

Curing … Protect against rapid drying by water misting, wet burlap, or non-solvent surface evaporation retardant for 24 hours.

Cleanup … All tools must be cleaned with water immediately after use.  Cured material can only be removed mechanically.


Do not apply GEM-PLAST TC when the temperature is expected to be below 40° F (4° C) within 48 hours, or when rain is imminent.  Follow Hot Weather concreting precautions when applying at temperatures above 77° F (25° C), or under sunny and windy conditions.  Maximum applied thickness must not exceed 1/4″ (6.35 mm).


Avoid direct contact with this product, as it may cause skin and eye irritation. Utilize gloves and safety glasses to minimize direct contact. Avoid inhalation of dust. Inhalation may cause respiratory irritation and/or lung disease (silicosis). This product contains silicon dioxide, which is classified by the IARC and NTP as probably carcinogenic to humans (IARC Group 2A). The use of NIOSH-approved respiratory protection is recommended in dusty environments. Refer to Safety Data Sheet for complete health and safety information.

Keep product out of reach of children. Not for consumption.