Sikacrete®-920 UHP
Ultra-high performance (UHP) cementitious concrete repair mortar with optional steel fibre-reinforcement to produce an ultra-high-performance fibre-reinforced concrete (UHPFRC)
Sikacrete®-920 UHP is a one-part, cementitious, ultra-high strength concrete repair mortar which can be mixed with steel fibres on demand to obtain an ultra-high-performance fibre-reinforced concrete (UHPFRC). Suitable for strengthening of existing steel reinforced concrete structures by supplementing the steel reinforced concrete and for structures made of UHPFRC with steel reinforcement. Layer thickness up to 80 mm. Sikacrete®-920 UHP with steel fibres meets the requirements of SIA 2052 (UB).
- Ultra-high mechanical properties.
- Adaptable - can be used with or without steel fibres.
- Ideal for structures subjected to high stress or repeated loading, but cannot be renovated regularly (e.g. highway bridges).
- When compared against conventional concrete, reduced amount required to provide same properties.
- Allows significant reduction of application thickness, or reduced area of structural elements (e.g. beams, pillars, columns, etc.).
- Homogeneous and uniform in nature - no coarse aggregate which could segregate.
- Post-crack tensile strength.
- Very high energy-absorbing properties ('toughness').
- High impact and abrasion resistance.
- Resistant to dynamic loading and seismic activity.
- Very dense material, with low porosity and permeability.
- Minimised crack tendency for long durability.
- Excellent freeze-thaw resistance.
- Rapid strength gain, accelerating construction times.
- Cost-effective (reduced thicknesses required, shortened construction times, low maintenance costs and depreciation, etc.).
- Euroclass A1 reaction to fire.
Usage
Sikacrete®-920 UHP is recommended for:- Refurbishment of bridge structural decks and car park slabs.
- Creation of, and repair of, floors.
- Construction of prefabricated elements (e.g. drainage channels, columns, etc.).
- Other application fields (e.g. abrasion-exposed hydraulic and industrial structures).
- Reducing specified concrete thicknesses.
- Any structure requiring UHP or UHPFRC.
Advantages
- Ultra-high mechanical properties.
- Adaptable - can be used with or without steel fibres.
- Ideal for structures subjected to high stress or repeated loading, but cannot be renovated regularly (e.g. highway bridges).
- When compared against conventional concrete, reduced amount required to provide same properties.
- Allows significant reduction of application thickness, or reduced area of structural elements (e.g. beams, pillars, columns, etc.).
- Homogeneous and uniform in nature - no coarse aggregate which could segregate.
- Post-crack tensile strength.
- Very high energy-absorbing properties ('toughness').
- High impact and abrasion resistance.
- Resistant to dynamic loading and seismic activity.
- Very dense material, with low porosity and permeability.
- Minimised crack tendency for long durability.
- Excellent freeze-thaw resistance.
- Rapid strength gain, accelerating construction times.
- Cost-effective (reduced thicknesses required, shortened construction times, low maintenance costs and depreciation, etc.).
- Euroclass A1 reaction to fire.
Packaging
25 kg standard bag and 900 kg bulk bags (steel fibres are available in 20kg bags)
Colour
Grey powder
Product Details
Chemical Base
Powder component: cement, additives and selected aggregates
Optional second component: steel fibres (Bekaert OL Steel Fiber 13/.20 or Krampe Harex DG 12.5/.20)
Shelf Life
6 months from date of production
Storage Conditions
Product must be stored in original, unopened and undamaged sealed packaging in dry conditions at temperatures between +5 °C and +30 °C.
Product Declaration
Complies with the general requirements of EN 1504-3: Class R4.
Mixed with steel fibres, it complies with the requirements of SIA 2052: Class UB.
Maximum Grain Size
Approximately 1.0 mm
Soluble Chloride Ion Content
≤ 0.05 % | (EN 1015-17) |
Abrasion Resistance
Hydraulic abrasion | CNR 0.9 (Classe RM2) | (NFP 18-490) |
Compressive Strength
Sikacrete®-920 UHP without steel fibres:
| 24 hours | ≥ 45 MPa |
| 7 days | ≥ 90 MPa |
| 28 days | ≥ 115 MPa |
| (EN 206) |
Sikacrete®-920 UHP with steel fibres:
| 24 hours | ≥ 75 MPa |
| 7 days | ≥ 135 MPa |
| 28 days | ≥ 160 MPa |
Modulus of Elasticity in Compression
| Without steel fibres: ~40 GPa | (EN 13412) |
Flexural Strength
Sikacrete®-920 UHP without steel fibres:
| 24 hours | ≥ 6 MPa |
| 7 days | ≥ 10 MPa |
| 28 days | ≥ 17 MPa |
Sikacrete®-920 UHP with steel fibres:
| 24 hours | ≥ 17 MPa |
| 7 days | ≥ 30 MPa |
| 28 days | ≥ 35 MPa |
Tensile Strength
UHPFRC Type UB (with 250 kg steel fibres per m³ mortar added; 12.5%, weight % of powder)
| fute | > 10 MPa | (SIA 2052) |
| futu | > 12 MPa | |
| eutu | > 2 ‰ |
Shrinkage
| ~300 μm/m after 28 days | (EN 12617-4) |
NOTE: Data determined with product without fibres.
Tensile adhesion strength
| 28 days | ≥ 4.0 MPa |
Reaction to Fire
| Euroclass A1 | (EN 13501-1) |
Freeze Thaw De-Icing Salt Resistance
| Bond strength on concrete after freeze-thaw (50 cycles with salt) | ≥ 3.5 MPa |
Capillary Absorption
| Without steel fibres: 0.02 kg/(m2 * h0.5) | With steel fibres: 0.029 kg/(m2 * h0.5) | (EN 13057) |
Water Penetration under Pressure
| ~3 mm (at 5 bar, without steel fibres) | (EN 12390-8) |
Carbonation Resistance
| dk ≤ control concrete MC (0.45) | (EN 13295) |
Service Temperature
-30 °C to +80 °C
Chloride Ion Ingress
| Without steel fibres: < 0.134% | (EN 13396) |
Application
Mixing Ratio
9.2 to 9.9 % water:
-
2.3 to 2.45 litres of water for 25 kg of powder
-
83 to 89 litres of water for 900 kg of powder
Optional steel fibre dosage: 250 kg/m³ mortar (~3.2 Vol%)
-
3.12 kg of steel fibres per 25 kg of powder
-
112 kg of steel fibres per 900 kg of powder
NOTE: Recommended steel fibres: Bekaert Dramix OL 13/.20 or Krampe Harex DG 12.5/.20.
Layer Thickness
20 mm to 80 mm
Ambient Air Temperature
+5 °C to +30 °C
Substrate Temperature
+5 °C to +30 °C
Pot Life
| with 9.2 % water | ~20 to 30 minutes (at +20 °C) |
| with 9.9 % water | ~45 to 60 minutes (at +20 °C) |
NOTE: Pot life is strongly influenced by water demand!
Applied Product Ready for Use
| Walkable after approximately | 12 hours at temperatures over +10 °C |
| Trafficable after approximately | 24 hours at temperatures over +10 °C |
Initial set time
~3 hours at +20 °C
Final set time
Approximately 8 to 9 hours at +20 °C
Fresh mortar density
| Without fibres: approximately 2.33 kg/l | With fibres: approximately 2.5 kg/l |
Consumption
Approximately 2,130 kg powder is needed to prepare 1 m³ of fresh mortar (~2.13 kg/m² and mm thickness).
NOTE: Consumption depends on the roughness and absorbency of the substrate. This figure is theoretical and does not allow for any additional material due to surface porosity, surface profile, variations in level or wastage, etc.
Yield
Without fibres:
-
25 kg of powder will yield ~11.7 litres of mortar.
-
900 kg of powder will yield ~420 litres of mortar.
With fibres:
-
25 kg of powder will yield ~12.2 litres of mortar.
-
900 kg of powder will yield ~440 litres of mortar.
NOTES ON INSTALLATION
For professional use only!
Strictly follow installation procedures as defined in method statements, application manuals and working instructions which must always be adjusted to the actual site conditions.
SUBSTRATE PREPARATION
Concrete must be fully cured, clean and sound to ensure good adhesion. All loose traces of concrete or mortar, dust, grease oil, etc., must be removed.
Damaged or contaminated concrete must be removed to obtain a keyed surface. Non-impact / vibrating cleaning methods (e.g. shot blasting, sandblasting or high-pressure water jetting) are recommended. Aggregate should be clearly visible on the surface of the concrete structure after surface preparation.
Cut the edges of the repair vertically to a minimum depth of 20 mm.
Water saturation
Saturate the concrete substrate with water for at least 12 hours before application. The surface shall be matt-damp (saturated surface dry); any standing water on the substrate must be removed.
Insufficient saturation of the substrate before application means that the UHPB does not achieve its full mechanical properties.
Bonding slurry (optional)
For very well prepared, matt-damp substrates with a roughness depth of 3 to 5 mm, a bonding bridge is generally not required.
If the bonding requirements are very high, the use of SikaScreed®-20 EBB is recommended. Alternatively, Sika MonoTop®-1010 can be used for normal bonding requirements.
MIXING
Mixing Sikacrete®-920 UHP requires a high shear mixer and qualified personnel on-site. The number of mixers should be adjusted to reduce waiting time between batches, depending on the volume of material to be placed. Since a wheelbarrow or a buggy will be used to transport the fresh material to the pouring location, the mixer(s) must be raised high enough to ensure that it discharges properly. A platform can also be used next to the mixer to allow workers to batch prorperly and safely. The mixer(s) should be kept as clean as possible between batches in order to guarantee the performance of subsequent batches. Alternative methods of transporting the prepared Sikacrete®-920 UHP can be approved, such as a vehicle mounted agitators and pumps. All alternatives should be discussed with your Sika® representative prior to commencing.
Mixing procedure: wet down the mixer and add the minimum or pre-defined amount of water and start the mixer. Add the powder while mixing and - in case of fibre addition - gradually introduce all steel fibres. Continue mixing until an homogeneous mix is achieved (typically at least 5 to 8 minutes are required). Eventually add more water untile the desired consistency is achieved, but do not exceed the maximum allowed water amount! The total mixing time should be no longer than 8 to 10 minutes.
Small amounts of material can also be mixed using a dual paddle mixer attached to a powerful electric drill using the same mixing procedure as described before.
NOTE: Suitability for installation of slopes must be demonstrated on a project-specific basis. Experience has shown that, depending on the roughness of the substrate and working with a water amount around the minimum stated, slopes of up to 3% are possible.
APPLICATION
Do not apply Sikacrete®-920 UHP in direct sunlight and / or strong wind. Do not apply Sikacrete®-920 UHP at temperatures below +5 °C, nor above +30 °C.
The mixed Sikacrete®-920 UHP mortar should be placed as quickly as possible after it has been properly mixed and discharged into a wheelbarrow or dumper. Transport the mixed mortar to the prepared application area and pour onto the prepared and matt-damp substrate. Spread the mortar to the desired thickness. Sikacrete®-920 UHP is self-consolidating and can be easily levelled.
Use the material 5 to 15 minutes after mixing to take advantage of the optimum flow properties. The placement has to be finished within the pot life of the mix (approximately 20 to 40 minutes at +20 °C, depending on the water amount used).
When finishing the surface of an overlay, it is recommended to use a vibrating screed to uniformly distribute the mortar. Adding additional water to the surface of the material for finishing purposes is not permitted. To facilitate smoothing of the surface, an intermediate treatment can be sprayed uniformly over the surface after the first smoothing.
CURING TREATMENT
Protect fresh mortar immediately from premature drying using an appropriate curing method (e.g. an approved Sika® curing compound, wetted jute, burlap or similar, moist geotextile membrane, hessian, polyethylene sheet, etc.).
The curing period is dependent on ambient conditions.
NOTE: Curing compounds must not be used when they could adversely affect subsequently applied products and systems.
CLEANING OF TOOLS
Clean all tools and application equipment with water immediately after use. Hardened material can only be mechanically removed.