High density, cementitious fireproofing

Product Description

MONOKOTE® Z-146 high density cementitious fireproofing has been developed by GCP Applied Technologies to meet specialty, commercial and industrial fireproofing requirements.

Monokote Z-146 is a Portland cement-based, factory-mixed material requiring only the addition of water on the jobsite for application. It is spray applied directly to structural steel (beams and columns), providing up to 4 hours of fire resistance. Its physical characteristics are excellent for areas exposed to environmental or climatic conditions.

Monokote Z-146 may be used in areas where high durability is required such as parking garages. This product is ideal for use in clean room environments where issues such as particle emissions and off gassing are critical to the interior environment within the building.

Features & Benefits

Monokote Z-146 offers the following advantages to architects, engineers, and applicators:

  • Factory pre-mixed - Ready to use. No job site proportioning required. Simply add water in a standard paddle-type plaster mixer and apply with conventional plastering equipment.
  • Non-toxic - The factory-mixed blend of common Portland cement and other inert materials requires only the addition of water for mixing and application.
  • Attractive finishes - Monokote Z-146 may be sprayed or hand troweled after spraying to achieve a lightly textured appearance.
  • Equipment versatility - Monokote Z-146 can be mixed in standard plaster mixer. After mixing, Monokote Z-146 may be spray-applied with commonly available pumping and spraying equipment.
  • Moisture resistant - The Portland cement base affords excellent fire protection characteristics in areas subjected to high humidity.
  • Durable - Hardness and durability help resist accidental physical damage.
  • Weatherable - Able to withstand freeze/thaw, wind, rain and other climatic conditions.


Monokote Z-146 may be used in parking garages, exterior areas, mechanical rooms and other areas where a highly durable product is required.

Delivery & Storage

All material to be used for fireproofing should be delivered in original unopened packages bearing the name of the manufacturer, the brand and proper Underwriters Laboratories Inc. labels for fire hazard and fire resistance classifications.

The material should be kept dry until ready for use. Keep packages of material off of the ground, under cover and away from sweating walls and other damp surfaces. All bags that have been exposed to water before use should be discarded. Stock of material is to be rotated and used before its expiration date.

Steel & Concrete Surfaces

Prior to the application of Monokote Z-146, an inspection should be made to determine that all steel surfaces are acceptable to receive fireproofing. The steel to be fireproofed should be free of oil, grease, excess rolling compounds or lubricants, loose mill scale, excess rust, noncompatible primer, lock down agent or any other substance that will impair proper adhesion. Where necessary, the cleaning of steel surfaces to receive fireproofing will be the responsibility of the general contractor.

Prior to application of Monokote Z-146, a bonding agent, approved by the fireproofing manufacturer, should be applied to all concrete substrates to receive Monokote Z-146.

The project architect will determine if the painted/primed steel to receive fireproofing has been tested in accordance with ASTM E119, to provide the required fire resistance rating.

Performance Characteristics

Physical Properties Recommended* Specifications Test Method/Notes**
Dry density Min. 40 pcf (640 kg/m3 ) ASTM E605
Bond strength Min. 10,000 psf (478 kN/m2) ASTM E736
Compressive strength @ 10% deformation 500 psi (3.45 KPa) ASTM E761
Hardness 40 ASTM D2240
Yield Theoretical maximum
Color Natural concrete gray
Volatile Organic Content (off gassing) at 122 °F (50 °C)organic compounds C6-C28 Less than 1 PPMW part per million by weight t Dynamic headspace (Thermal desorbtion gas chromatography—mass spectrometry)
Leachable ammonia Less than 50 PPB, 50 nanograms/mg Leachable ion by ion chromatography

* Independent test values exceed recommended specification limits. Report available upon request
** ASTM International test methods modified for Bond Strength and Compressive Strength, where required, for high density, high performance products.


  • Monokote Z-146 should be mixed by machine in a conventional, plaster-type mixer or a continuous mixer specifically modified for cementitious fireproofing. The mixer should be kept clean and free of all previously mixed material. Adjust the mixer speed in a conventional mixer to the lowest speed which gives adequate blending of the material and a mixer density of 50 to 60 pcf (800 to 961 kg/m3) of material.
  • Using a suitable metering device and a conventional mixer, add all water to the mixer as the blades turn. Mixing should continue until the mix is lump-free, with a creamy texture. All material is to be thoroughly wet. Overmixing Monokote Z-146 will reduce pumping rate and will negatively affect in-place density and mechanical properties.


  • Monokote Z-146 material should not be used if it contains partially set, frozen or caked material.
  • Monokote Z-146 should have a minimum average dry, in-place density of 40 lbs/ft3 (640 kg/m3).
  • Monokote Z-146 is formulated to be mixed with water at the job site.
  • Monokote Z-146 is applied directly to the steel, at various rates of application which will be job dependent, using standard plastering type equipment or continuous mixer/pump units. A spray gun, with a properly sized orifice and spray shield and air pressure at the nozzle of approximately 20 psi (0.138 MPa), will provide the correct hangability, density and appearance.

Note: If freshly sprayed Monokote Z-146 does not adhere properly, it is most likely due to a too wet mix, poor thickness control, or an improperly cleaned substrate.


An air and substrate temperature of 40 °F (4.5 °C) minimum should be maintained for 24 hours prior to application, during application and for a minimum of 72 hours after application of Monokote Z-146.

Field Tests

The architect will select an independent testing laboratory (for which the owner will pay) to sample and verify the thickness and density of the fireproofing in accordance with the provisions of ASTM E605-77, Standard Test Method for Thickness and Density of Sprayed Fire-Resistive Material Applied to Structural Members or Uniform Building Code Standard No. 43–8, Thickness and Density Determination for Spray Applied Fireproofing.

Note: No recognized field bond strength test procedure exists for sprayed fireproofing materials with bond strengths greater than 1,000 psf (4,882 kg/m2) such as Monokote Z-146. Where bond strength specifications exceed 1,000 psf (4,882 kg/m2) it is recommended that independent laboratory test data based upon a modified version of ASTM E736 be submitted to verify specification compliance.


Monokote Z-146 is slippery when wet. Signs reading “SLIPPERY WHEN WET” should be posted in all areas in contact with wet fireproofing material. Anti-slip surfaces should be used on all working surfaces.

SDS (Safety Data Sheet) for Monokote Z-146 are available on our web site at or call toll free at 866-333-3SBM. | For technical information:

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

Monokote is a trademark, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© Copyright 2017 GCP Applied Technologies Inc. All rights reserved.

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GCP Applied Technologies Inc., 2325 Lakeview Parkway, Alpharetta, GA 30009, USA
GCP (Hong Kong) Ltd., 6 On Chuen Street, On Lok Tsuen Ind Area, Fanling, Hong Kong
This document is only current as of the last updated date stated below and is valid only for use in Hong Kong. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2022-11-18