Sikafloor®-21 PurCem® LP
Sikafloor®-21 PurCem® LP is a three part, water dispersed medium to high strength coloured polyurethane modified, cement and aggregate screed with self smoothing properties. It has an aesthetic, smooth textured aggregate surface providing medium slip resistance and is typically installed at 3 to 6 mm thickness.
- Good chemical resistance. Resists a wide range of organic and inorganic acids, alkalis, amines, salts and solvents. Please refer to the Chemical Resistance Chart or consult your local Technical Department
- Similar coefficient of thermal expansion to concrete, allowing movement with the substrate through normal thermal cycling. It will perform and retain its physical characteristics through a wide temperature range from -5 °C up to +65 °C
- Bond strength in excess of the tensile strength of concrete. Concrete will fail first
Usage
Sikafloor®-21 PurCem® LP is used as a scratch coat primer, basecoat and wear coat layer in Sikafloor®PurCem® system build ups, in areas of medium to heavy loading, high chemical exposure and abrasion, such as in:- Food processing plants (wet or dry process areas, freezers and coolers)
- Chemical plants
- Laboratories
- Workshops
Advantages
- Good chemical resistance. Resists a wide range of organic and inorganic acids, alkalis, amines, salts and solvents. Please refer to the Chemical Resistance Chart or consult your local Technical Department
- Similar coefficient of thermal expansion to concrete, allowing movement with the substrate through normal thermal cycling. It will perform and retain its physical characteristics through a wide temperature range from -5 °C up to +65 °C
- Bond strength in excess of the tensile strength of concrete. Concrete will fail first
- Non tainting / odourless
- VOC free
- High mechanical resistance. Behaves plastically subject to impact. Will deform but will not crack or debond
- High abrasion resistance resulting from its silica aggregate structure
- Can be applied to substrates with high moisture content (7 days old or mature damp concrete)
- Jointless. Extra expansion joints are not necessary; simply maintain and extend existing expansion joints up through the Sikafloor® -PurCem® flooring system
- Easily maintained
Packaging
Part A : 3.00 kg plastic drum
Part B : 3.00 kg plastic jerrycan
Part C : 14.00 kg plastic lined, double paper bags
Part A+B+C: 20.00 kg ready to mix units
Colour
Part A : Liquid / coloured
Part B : Liquid / brown
Part C : Powder / natural grey
Available colours : Green, Grey, Light Grey, Cream, Red.
Product Details
APPROVALS / CERTIFICATES
Conforms to the requirements of EN 13813: 2002 as CT - C50 - F10 - AR0.5
Conforms to the requirements of EN 1504-2 for principle 5 (PR) and 6 (CR) as a coating (C)
All other values indicated are internal test results.
Composition
Part A : Water borne polyol
Part B : Isocyanate
Part C : Aggregates, cement and active fillers
Shelf life
Parts A and B: | 12 months from date of production. Must be protected from frost. |
| Part C: | 6 months from date of production. Must be protected from humidity. |
Storage conditions
If stored properly in original, unopened and undamaged sealed packaging, in dry conditions at temperatures between +18 °C and +30 °C.
Density
| Part A | ~1.07 kg/L |
| Part B | ~1.24 kg/L |
| Part C | ~1.91 kg/L |
| Part A+B+C mixed | ~1.99 ± 0.03 kg/L |
Shore D Hardness
| ~80 – 85 |
Compressive Strength
| 28 days | ~ 44 N/mm2 |
| 28 days | ~ 50 N/mm2 |
Tensile Strength in Flexure
| 28 days | ~ 14.7 N/mm2 |
| 28 days | ~ 10 N/mm2 |
Tensile Strength
| 28 days | ~ 6.5 N/mm2 |
Tensile Adhesion Strength
| ~ 1.75 N/mm2 | (failure in concrete) |
(1.5 N/mm2 is the minimum pull off strength of the recommended concrete substrate)
Reaction to Fire
| Class B(fl) S1 |
Chemical Resistance
Resistant to many chemicals. Please ask for a detailed chemical resistance chart.
Permeability to Water Vapour
| To water vapour (4.8 mm) | 0.115 g/h/m2 |
Temperature Resistance
The product is not designed to withstand thermal shock. Hot steam cleaning is not recommended. Use Sikafloor®-20 PurCem® LP 9 mm
Sikafloor®-21 PurCem® LP can be subject to thermal shock < 70 °C at 6 mm.
Skid / Slip Resistance
| Substrate | SRV Dry | SRV Wet |
| Sikafloor®-21 PurCem® LP | 70 | 60 |
TRRL Pendulum, Rapra 4S Slider
Application
Mixing Ratio
Part A : B : C = 1 : 1 : 4.67 (packaging size = 3 : 3 : 14) by weight
Ambient Air Temperature
+10 °C min. / +30 °C max.
Layer Thickness
3 mm min. / 6 mm max
Relative Air Humidity
85 % max.
Dew Point
Beware of condensation!
The substrate and uncured floor must be at least 3 °C above dew point to reduce the risk of condensation or blooming on the floor finish.
Substrate Temperature
+10 °C min. / +30 °C max.
Substrate Moisture Content
The substrate can be dry or damp (saturated surface dry or SSD) with higher moisture content (No ponding water). Check rising moisture.
The substrate needs to be visibly dry and have adequate pull-off strength min. 1.5 N/mm2.
Pot Life
| Temperature | Time |
| +10 °C | ~35 - 40 min |
| +20 °C | ~22 - 25 min |
| +30 °C | ~15 - 18 min |
| +35 °C | ~12 - 15 min |
Curing Time
| Temperature | Foot Traffic | Light Traffic | Full Cure |
| +10 °C | ~24 h | ~48 h | ~7 d |
| +20 °C | ~18 h | ~24 h | ~4 d |
| +30 °C | ~12 h | ~18 h | ~3 - 4 d |
| +35 °C | ~12 h | ~18 h | ~3 - 4 d |
Notes: Times are approximate and will be affected be changing ambient and substrate conditions, particularly temperature and relative humidity.
If used other primers than Scratch Coat refer the Technical Data Sheet of the respective product. Make sure that the primer and the scratch coat layer is fully cured before application of Sikafloor® PurCem® previous layer.
Consumption
| Layer | Product | Consumption |
| Scratch Coat | Sikafloor®-21 PurCem® LP | ~1.5 kg/m2 |
| Body Coat | Sikafloor®-21 PurCem® LP | ~1.9 kg/m2/mm |
This figure is theoretical and does not allow for any additional material due to surface porosity, surface profile, variations in level or wastage etc.
MIXING
Material and ambient temperature will affect the mixing process. If necessary, condition the materials for best use to 18 °C - 27 °C.
Premix part A and B separately, make sure all pigment is uniformly distributed with a low speed electric stirrer.
Start mixer and add parts A and then B and blend for 30 seconds.
Gradually add part C (aggregate) to the mixed resin parts over a period of 15 seconds. DON’T DUMP!
Allow part C to blend for further 2 minutes minimum, to ensure complete mixing and a uniform moist mix is obtained.
During the operations, scrape down the sides and bottom of the container with a flat or straight edge trowel at least once (parts A+B+C) to ensure complete mixing. Mix full units only.
When adding aggregate to prepare a patching / levelling mortar, gradually add the 6 kg of 2 - 3 mm dry quartz sand immediately after mixing the full set.
Use a low speed electric stirrer (300 - 400 rpm) for mixing parts A+B+C.
For preparation of the mortar mix use a pan type revolving mixer.
APPLICATION
Prior to application, confirm substrate moisture content, r.h. and dew point.
Proceed with placement of the material to facilitate the release of entrapped air from the mix and CO2 from the reaction. Do so in every batch mixed in a consistent manner in order to avoid colour differences due to increased temperatures in the reaction.
Pour the mixed Sikafloor®-21 PurCem® LP onto the substrate and work with a toothed trowel or pin screed to the desired thickness, achieving a flat surface. A straight edge trowel can also be used to smooth out the marks of the tooth trowel or instead of it. Take care to spread newly placed materials across the transition of previously applied mixes before the surface begins to set.
Remove air with a spike roller immediately (less than two minutes after placing).
Roller spikes must be at least three times longer than the product thickness applied.
Allow a minimum 18 hours cure period at 30 °C before light traffic.
Flow check
| Flow = | 310 ± 10 mm |
CLEANING OF EQUIPMENT
Clean all tools and application equipment with Thinner C immediately after use.
Hardened / cured material can only be mechanically removed.
CLEANING
To maintain the appearance of the floor after application, Sikafloor®-21 PurCem® LP must have all spillages removed immediately and must be regularly cleaned using rotary brushes, mechanical scrubbers, scrubber dryers, high pressure washers, wash and vacuum techniques, etc., using suitable detergents and waxes.