Cemtop GP Advanced: Technical Details, Specifications, Features and Entities

Product Overview

Cemtop GP Advanced is a high-performance, self-smoothing cementitious floor underlay product manufactured by Fosroc International Limited. It is designed as a heavy-duty underlay that forms a smooth, hard surface suitable for a variety of floor finishes, particularly carpet and ceramic tiles.

Key Features and Advantages

Cemtop GP Advanced offers several distinctive advantages for flooring applications:

• Fast Application: Specifically formulated for fast and easy application with enhanced flow properties and excellent wet-edge retention exceeding 20 minutes at 20°C
• Pump-Applied Efficiency: Fast application by pump enables large floor areas to be completed in a single working day
• Direct Application: Can be applied directly onto prepared concrete floors, eliminating the need for traditional sand cement screeds
• Dimensional Stability: Can be installed in large areas without significant deformation or shrinkage
• Strong Adhesion: Demonstrates excellent adhesion to prepared substrates, ensuring strong bonding between underlay and concrete floor
• Rapid Hardening: Rapid hardening and curing allows speedy access for foot traffic and overlay installation with carpet, vinyl, and other finishes
• One-Pack Convenience: Applied by pump, eliminates on-site batching and ensures consistency of the mixed product
• Low VOC Content: Contains only 21.6 grams per litre of volatile organic compounds (test certificate available on request)
• High Thickness Capability: Able to be applied in thicknesses of up to 50mm without addition of aggregate
• Safety: RCS (Respirable Crystalline Silica) Hazard Free—classified as not hazardous for RCS in accordance with Australian Inventory of Industrial Chemicals; contains <0.1% RCS

Product Composition

Cemtop GP Advanced consists of a polymer-modified formulation comprising:

• Selected cements (primary binding components)
• Graded aggregates
• Polymers and flow agents (enhancing application properties and performance characteristics)

The product is supplied as a grey powder requiring only the addition of water to produce a self-smoothing, free-flowing material.

Physical and Chemical Properties

Compressive Strength (AS 1478.2 2005)

• 1 Day: 10 MPa
• 7 Days: 20 MPa
• 28 Days: 30 MPa

Modulus of Rupture (Flexural Strength) (AS 1012.11-2000)

• 1 Day: 2 MPa
• 7 Days: 3 MPa
• 28 Days: 5 MPa

Indirect Tensile Strength (AS 1012.10-2000)

• 1 Day: 1 MPa
• 7 Days: 2 MPa
• 28 Days: 3 MPa

Application and Curing Times

• Time to Foot Traffic @ 23°C: 4 hours
• Carpet Overlay (up to 10mm thick): 24 hours
• Vinyl Overlay (up to 5mm thick): 2 days
• Vinyl Overlay (5-10mm thick): 3 days
• Vinyl Overlay (10-20mm thick): 4 days

Design and Application Specifications

Application Thickness Range

Cemtop GP Advanced is designed for application thicknesses of 2mm to 50mm. Thicker applications are possible; however, local Fosroc sales offices should be consulted for specific advice.

Substrate Requirements

The product can be applied to clean, sound, and well-prepared concrete substrates that meet the following criteria:

• Substrate Condition: Free from loose material, oil, grease, paint, and other contamination
• Compressive Strength: Minimum 20 MPa
• Relative Humidity: Must not exceed 80% at time of installation
• Concrete Age: New concrete should be at least 14 days old
• Moisture Content: Substrate moisture content must not exceed 5% (when tested using a Tramex moisture meter)

Temperature Requirements

• Recommended Application Temperature Range: 10°C to 35°C
• Low-Temperature Adjustment: When substrate temperature will be below 15°C prior to initial set, Cemtop GP Advanced must be mixed at the low end of the recommended water addition rate (4.0 litres per 20kg bag)
• Consultation Required: If site conditions fall outside the recommended range, Fosroc should be consulted for advice

Mixing and Application Instructions

Water Addition Ratio

Each 20kg bag of Cemtop GP Advanced requires the addition of 4.0 to 4.3 litres of clean, cool water to produce a free-flowing self-smoothing consistency.

Mixing Process

• Pour mixing water into a clean mixing vessel
• Add powder slowly to water while mixing continuously
• Use a heavy-duty mixer fitted with a suitable spiral paddle
• Continue mixing for at least 3 to 4 minutes until a smooth, creamy consistency is obtained
• Do not mix more than can be reasonably laid within the flow time of the material

Application Methods

Installation by Pump (Specialised Activity):

• Prepared by experienced contractors with full training
• Prime surface with Nitoprime 330 diluted (4 parts water to 1 part primer) and allow to dry
• Apply Cemtop GP Advanced to required thickness onto dry, primed surface

Installation by Hand (Alternative Method):

• Prime surface with Nitoprime 330 diluted 4:1 with water and allow to dry
• Alternatively, use Nitobond AR diluted 2:1 with water as primer
• Pour mixed material onto dry primed surface
• Spread with trowel and allow to self-smooth
• Roll surface with purpose-made spiked roller
• Best results achieved with continuous pouring and levelling

Surface Preparation

• Remove excess laitance by light scabbling or captive shot blasting followed by vacuuming
• Remove oil and grease contamination
• Fill large cracks and holes using a mix of equal volumes of Cemtop GP Advanced and clean sharp sand with water addition; prime repair areas with Nitoprime 330

Priming

• Prime substrate with Nitoprime 330 to seal and prevent air release
• Extremely porous substrates may require two priming coats
• Allow primer coats to dry before applying Cemtop GP Advanced

Coverage and Yield

Theoretical Coverage

When 4.0 litres of water is added per 20kg bag:

• Approximate Yield: 11.7 litres per 20kg bag
• Approximate Coverage: 1.2 m² @ 10mm thick

When 4.3 litres of water is added per 20kg bag:

• Approximate Yield: 12.0 litres per 20kg bag

Nitoprime 330 Coverage

6-8 m²/litre (after dilution with clean water as specified)

Note: Coverage figures are theoretical—practical coverage will be reduced due to wastage factors and substrate variations.

Storage and Shelf Life

• Shelf Life: 2 years from date of manufacture when kept in original, unopened bags
• Storage Conditions: Store in dry conditions to preserve product integrity
• Condition Check: Do not use if lumps are present or if loss of workability is experienced (requiring more water addition)
• Temperature Effects: Shelf life may be reduced if stored at high temperatures and/or high humidity

Applications

Cemtop GP Advanced is suitable for use in:

• Residential Applications: Domestic building projects
• Commercial Applications: Commercial building projects
• Light Industrial Applications: Light industrial building projects
• New Construction Projects: Newly built structures requiring underlayment
• Refurbishment Projects: Renovation and upgrade of existing structures

Limitations

• Internal Use Only: Designed as an internal underlay material only, NOT a wearing course for traffic
• Not for Permanent Wetting: Must not be used in areas subject to permanent wetting, rising damp, or where back water pressure is likely
• Weather Protection: Protect from direct sunlight and/or drying winds during application and final curing period
• Reflective Cracking: If the surface onto which Cemtop GP Advanced is applied moves or cracks, reflective cracking may occur
• Not Compatible with Nitoflor PA: Nitoflor PA should not be applied to Cemtop GP Advanced polymer-modified cementitious screeds
• Workability: If mix stiffens, it should be discarded; do not attempt to re-mix with water
• Alternative for Traffic: Cemtop XD should be considered for applications subject to traffic wear

Supply and Available Formats

Cemtop GP Advanced is supplied in 20kg bags with product code FC630088-20KG, alongside associated primer products.

Safety Information

A Safety Data Sheet (SDS) is available from the Fosroc website and should be read carefully prior to use, as application or performance data may change over time.

References

• [1] Fosroc_Cemtop_HD30_TDS.pdf
• [2] Fosroc_Cemtop_GP_Advanced_TDS.pdf
• [3] Fosroc_Cemtop_Screed_TDS.pdf
• [4] Fosroc_Cemtop_XD_TDS.pdf