Guncrete E: High Strength Dry-Spray Concrete Repair Mortar

Overview

Guncrete E is a high strength, low shrinkage, high build dry-spray applied repair mortar supplied as a ready-to-use dry powder for use with standard dry spray gunite or shotcrete equipment. This cement-based repair mortar is manufactured by Fosroc and designed specifically for structural concrete repair applications.

Key Features and Advantages

Guncrete E offers several distinctive advantages that make it an ideal choice for concrete reinstatement and repair work:

• Made in Australia - locally manufactured product
• RCS Hazard Free - Contains <0.1% Respirable Crystalline Silica (RCS), classified not hazardous in accordance with Australian Inventory of Industrial Chemicals
• High Build Formulation - Requires fewer applications of product compared to standard repair mortars
• High Strength - Suitable for structural repairs
• High Early Strength - Provides reduced back-to-service time, enabling faster project completion
• Low Drying Shrinkage - Delivers long-term dimensional stability
• Low Rebound - Minimizes material waste on site
• Chloride Free - Protects embedded reinforcement from corrosion
• Suitable for Galvashield Anodes - Compatible with incipient anode protection and cathodic protection systems

Applications

Guncrete E is particularly suited for the reinstatement of large areas of concrete and localized patch repairs in critical infrastructure, including:

• Sea walls
• Bridge decks and piers
• Tunnels
• Sewer pipes
• Other demanding structural environments

Technical Specifications

Compressive Strength Properties

Guncrete E demonstrates excellent strength development across standardized curing periods, tested according to EN 2190:1999 and AS 1478.2 - 2005:

Curing Time	Compressive Strength	EN 1504 R4 Requirement
1 day	35 MPa	≥ 45 MPa
7 days	60 MPa
28 days	70 MPa & 84.0 MPa

The material exceeds the EN 1504 R4 requirement of ≥ 45 MPa with its 28-day strength of 84.0 MPa, demonstrating superior performance for structural applications.

Additional Mechanical Properties

Property	Test Method	Standard	Test Result
Bond Strength (Pull-off)	EN 1542:1999	≥ 2.0 MPa	3.2 MPa (without primer, pre-soak)
Flexural Strength	AS 1012.11 - 2000	—	10.1 MPa @ 28 days
Tensile Strength	AS 1012.10 - 2000	—	5.5 MPa @ 28 days
Elastic Modulus	EN 13412:2008	> 20 GPa	52.8 GPa
Chloride Ion Content	EN 1015-17:2000	≤ 0.05%	0.003%
Capillary Absorption	EN 1307:2002	≤ 0.5 Kg/(m² x h^0.5)	0.1 Kg/(m² x h^0.5)
Coefficient of Thermal Expansion	EN 1770:1990	Declared Value	16.3 x 10⁻⁶ /°C
Chloride Diffusion	Nordtest NT Build 443	—	De: 1.0 x 10⁻¹² m²/sec

Setting and Density

• Initial Set: 4.5 hours
• Final Set: 10 hours
• Fresh Wet Density: 2160 Kg/m³

Shrinkage and Expansion

• Drying Shrinkage: < 500 microstrains @ 7 days; < 600 microstrains @ 56 days
• Shrinkage and Expansion: Shrinkage 2.7 MPa; Expansion 2.8 MPa (tested per EN 12617-4:2002)

Durability Characteristics

• Carbonation Resistance: Conforms to EN 13295:2005 (≤ reference concrete)
• Alkali Reactive Particles: <0.1% (Non-Reactive) per RTA Rapid Mortar Bar Test RTA T363

Design Criteria

Guncrete E is engineered for specific application parameters:

• Vertical or Horizontal Applications: Up to 150mm thick
• Overhead Applications: Up to 80-100mm thick per layer (depending on substrate geometry)
• Multiple Layers: Thicker sections achievable through layered applications
• Minimum Thickness: 10mm (material should not be applied at less than this thickness)

Preparation Requirements

Proper surface preparation is critical for optimal performance:

Surface Treatment

• Saw cut or cut back repair location extremities to a minimum depth of 10mm to avoid feather-edging
• Break out the complete repair area to minimum depth of 10mm
• Remove all dust, unsound or contaminated material, plaster, oil, paint, grease, corrosion deposits, and algae
• Light scabbling or grit-blasting to roughen surface and remove laitance

Oil and Grease Removal

• Steam cleaning, detergent scrubbing, or proprietary degreaser application
• Assess decontamination effectiveness via pull-off test

Steel Reinforcement Preparation

• Expose all corroded steel in repair area
• Remove loose scale and corrosion deposits
• Clean steel to bright condition using grit-blasting (paying particular attention to bar backs)
• High-pressure wash with clean water immediately after grit-blasting if chloride contamination present

Steel Priming

• Apply one full coat of Nitoprime Zincrich
• Allow to dry before continuing
• Apply second coat if required

Application Instructions

Temperature Requirements

Low Temperature Conditions:

• Do not apply when substrate and/or air temperature is 5°C and falling
• Application may proceed at 5°C static temperature or 5°C and rising

High Temperature Conditions:

• Do not use at ambient temperatures above 35°C (causes premature setting)

Substrate Preparation Prior to Spraying

• Thoroughly wash substrate with clean water
• Pre-soak immediately prior to Guncrete E application
• Keep damp with clean water to satisfy absorption completely
• Remove excess water prior to spray application
• Ensure exposed reinforcing bars are firmly secured to avoid movement

Spray Application

• Apply using suitable guniting or shotcreting equipment
• Ensure thorough compaction around exposed reinforcement
• If sagging occurs on vertical surfaces, completely remove and reapply at reduced thickness
• Apply in layers as detailed in the Guncrete Application Guidelines

Finishing

• Strike off with straight edge
• Close with steel float
• Use wooden or plastic floats, or damp sponges for desired surface texture
• Avoid overworking completed surface
• Note: For smooth, closed render appearance, subsequent application of Renderoc FC is necessary

Curing Requirements

As a cement-based repair mortar, Guncrete E must be cured immediately after finishing in accordance with good concrete practice:

• Recommended Curing Method: Spray Concure A99 or Nitobond AR onto the finished surface in a continuous film
• Large Area Curing: Cure as trowelling progresses (0.5m² at a time) without waiting for entire area completion
• Fast Drying Conditions: Use supplementary curing with polythene sheeting taped at edges
• Cold Conditions: Protect finished repair from freezing

Protective Overcoating

Following curing, Fosroc recommends application of protective barrier/decorative coatings to limit chloride and carbon dioxide advance:

• Recommended Products: Dekguard range of protective, anti-carbonation coatings
• Application Timing: Apply after removal of curing membranes
• Benefits: Provides decorative, uniform appearance and protects surrounding structure

Supply and Coverage

Product Formats

Product	Pack Size	Product Code
Guncrete E	20 kg bags	FC302060-20KG
Nitoprime Zincrich	1 litre	FC322100-1L
Concure A99	20 litres	FC600909-20L
Nitobond AR	5 litres	FC320015-5L
Nitobond AR	20 litres	FC320015-20L
Fosroc Solvent 10	4 litres	FC600800-4L
Fosroc Solvent 10	20 litres	FC600800-20L

Coverage and Yield

Product	Yield
Guncrete E	Approximately 10.0 litres / 20 kg bag
Nitoprime Zincrich	7 m²/litre (approx.)
Concure A99	5 m²/litre
Nitobond AR	6 - 8 m²/litre

Note: Actual yield per bag of Guncrete E depends on the consistency used.

Storage and Shelf Life

Guncrete E has a 36-month shelf life from date of manufacture when kept in original, unopened bags. Store with reference to the manufacture date indicated on packaging.

Storage Precautions:

• Do not use if lumps are present in product
• Do not use if loss of workability is experienced (requiring more water addition)

Limitations

Guncrete E should not be used when:

• Temperature is below 5°C and falling
• Bags are partially mixed (do not mix part bags)
• Product is exposed to moving water during application
• Heavy rainfall occurs prior to final set (risk of surface scour)

Note: Contact Fosroc if doubts arise concerning temperature or substrate conditions.

Cleaning

• Guncrete E, Concure A99, Nitobond AR: Remove with clean water immediately after use
• Cured Material: Can only be removed mechanically
• Equipment used with Nitoprime Zincrich: Clean with Fosroc Solvent 10

Manufacturer Information

Guncrete E is manufactured and sold under license from Fosroc International Limited. Fosroc and the Fosroc logo are trade marks of Fosroc International Limited, used under license.

Distributor: Parchem Construction Supplies Pty Ltd, 1956 Dandenong Rd, Clayton VIC 3168, Australia

• Phone: 1800 812 864
• Website: www.fosroc.com.au
• ABN: 80 069 961 968

References

• [1] Fosroc_Guncrete_E_TDS.pdf