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Short answer: polyurea is a very flexible, 100% solids (solvent-free) waterproofing and protective coating formed when two components react within seconds. It is sprayed hot and at high pressure with a dedicated machine, gels in a few seconds and forms a seamless, monolithic layer on concrete, steel or wood. DEMCO polyurea systems have an elongation at break of 405–435% and a Shore D hardness of 45 ± 5; the theoretical consumption is 1.1 kg per m² for each 1 mm of thickness.
Because the reaction is so fast, polyurea is not applied by brush or roller; it is applied with machines that heat the two components separately and mix them at the spray gun. This speed allows application at ambient temperatures down to -30 °C and makes the surface touch-dry very quickly. The values below are taken from the technical data sheets of DEMCO polyurea and liquid membrane products.
Pure and hybrid polyurea
In pure polyurea systems the resin component is amine-based; in hybrid systems polyols are added to the amines, and the properties fall somewhere between polyurethane and polyurea. Both DEMCO polyurea products are pure polyurea. DEMCO POLYUREA /PURE contains no plasticizers and, according to its data sheet, is insensitive to humidity and temperature across many application temperatures. DEMCO POLYUREA /HB is sprayed onto metal, concrete and wood; it has a shorter recoat time and a higher elongation at break.
| Property | DEMCO POLYUREA /PURE | DEMCO POLYUREA /HB |
|---|---|---|
| Type | Pure polyurea, no plasticizers | Pure polyurea |
| Mixing ratio (by volume) | 1 A : 1 B | 1 A : 1 B |
| Pot life | 2–4 seconds | 5–10 seconds |
| Touch dry | 15–20 seconds | 10–15 seconds |
| Recoat time | 6 hours | 1 hour |
| Elongation at break (DIN 53504) | 405 ± 25% | 435% |
| Tensile strength at break | 18 ± 2 MPa | 18 ± 3 MPa |
| Tear resistance (ISO 34-1) | 95 N/mm | 90 ± 15 N/mm |
| Shore D hardness (ASTM D 2240) | 45 ± 5 | 45 ± 5 |
| Pull-off adhesion (TS EN 1542) | ~2.9 N/mm² | ~2.5 N/mm² |
| Taber abrasion (TS EN ISO 5470-1) | 136 mg | 136 mg |
| Reaction to fire (TS EN 13501-1) | E | E |
Both products are 100% solids and aromatic, and have been tested to EN 1504-2 under CE marking; impact resistance and water vapor permeability are Class 2. According to its data sheet, DEMCO POLYUREA /PURE can coat carbon steel or mild steel without a primer.
Where is it used?
- Roofs, terraces, balconies and car park roofs
- Car park and warehouse floors, industrial floor coatings
- Pools, water tanks, water and wastewater treatment plants
- Underground structures
- Refineries, power plants, fertilizer plants and mining facilities
- Food processing plants and cold stores
- Shipyards and marine environments
- Structural steel and oil and natural gas pipelines
Application steps
- Surface preparation: dust, dirt, oil, release agents, curing compounds, salts and weak particles are removed from the concrete by milling, water jetting or blasting, and the surface is cleaned of dust with an industrial vacuum. The concrete should have an average pull-off strength of 1.5 N/mm², a compressive strength of at least 25 N/mm² and a moisture content of no more than 4%. On steel, oil, grease, weld spatter and sharp edges are removed; the surface is blasted and primed on the same day to prevent flash rust.
- Primer: the cleaned concrete is primed with the epoxy moisture barrier DEMCO EPOX 110 PR, which is used under epoxy, polyurethane and polyurea coatings. Highly absorbent concrete may need 2 coats of primer. Holes, cracks and voids in damaged old concrete are repaired with DEMCO EPOX 110 PR mixed with sand.
- Preparing the material: component A is mixed with an air-driven mixer to obtain a uniform consistency and color. Components A and B are brought to 25 °C before application.
- Spraying: the material is applied with two-component machines with a 1:1 ratio, heated hoses and high-pressure spraying (Graco Reactor or similar). Components A and B are sprayed at a pressure of at least 2000 psi and at 65 °C; pressure and temperature are kept constant throughout the application. The material can be sprayed to any required thickness.
- UV protection: on surfaces exposed to continuous sunlight, a single coat of aliphatic polyurethane topcoat is applied. DEMCO PUR 410 TOP COAT UV/S can be applied over polyurea coatings.
- Protection: the coated surface is protected from water, dew and dust for at least 24 hours.
Coverage: how many kg per m²?
For both products the theoretical consumption is 1.1 kg per m² for each 1 mm of thickness; the thickness depends on the area of use. For example, a 2 mm application on a 500 m² area needs 500 × 2 × 1.1 = 1,100 kg in theory. Component A is supplied in 200 kg metal drums and component B in 220 kg metal drums. Surface roughness and application losses increase the real consumption; the exact quantity is determined for each project.
Polyurea or a brush-applied liquid membrane?
Polyurea requires a machine and an experienced application crew; it stands out on large areas, on jobs that must be back in service quickly and where high mechanical resistance is needed. For wet rooms, balconies, under tiles and on foundation walls, liquid membranes applied by brush, roller or trowel are more practical.
| Product | Type | Application | Drying | Consumption |
|---|---|---|---|---|
| DEMCO POLYUREA /PURE · /HB | Pure polyurea, 100% solids | Hot-spray machine | Touch dry in 10–20 seconds | 1.1 kg/m² (1 mm) |
| DEMCO PUR 210 1K | One-component polyurethane; cures with air humidity, high UV resistance | Brush-applied, 2–3 coats | Touch dry in 12–24 hours, full cure in 5–7 days | 0.600–0.700 kg/m² per coat |
| DEMCO BPU 230 | Two-component bitumen-polyurethane; elongation at break > 1500% | Brush-applied, 2 coats | Touch dry in 4 hours, fully dry in 7 days | 1.5–2 kg/m² in total |
| DEMCO BTM 400 2K | Water-based, modified bitumen-rubber and cement; TS EN 15814, W2B | Brush-applied | ~12 hours between coats | 1.50 kg/m² (1 mm) |
| DEMCO ELASTOMERİK 1K | One-component, water-based elastomeric resin | Brush, roller or spray, 2 coats | Touch dry in 3–4 hours, full cure in 7 days | 1.5–2 kg/m² in total |
| DEMCO ACR 250 W – 1K | One-component, water-based acrylic copolymer | Brush, roller or spray, 2 coats | Touch dry in 3–4 hours, full cure in 7 days | 1.5–2 kg/m² in total |
DEMCO BPU 230 and DEMCO BTM 400 2K are used on foundations, retaining walls and underground structures; DEMCO ELASTOMERİK 1K and DEMCO ACR 250 W – 1K in wet rooms, on balconies and on flat and pitched roofs. For all waterproofing products, see the insulation materials page.
Points to watch during application
- The surface must be dry, with a moisture content of no more than 4%; measure the moisture before application.
- The machine's pressure and temperature settings (at least 2000 psi, 65 °C) must be kept constant throughout the application.
- For intermediate coats or topcoats, follow the recoat time in the data sheet: 6 hours for DEMCO POLYUREA /PURE and 1 hour for DEMCO POLYUREA /HB.
- Aromatic polyurea must be protected with an aliphatic polyurethane topcoat where it is exposed to continuous sunlight.
- Shelf life is 6 months in unopened packaging. Store drums above 15 °C on wooden pallets, out of direct sunlight, and do not stack pallets.
- Applicators must wear protective clothing, goggles, shoes and gloves and avoid contact with skin and eyes.
Frequently asked questions
What is the difference between polyurea and polyurethane waterproofing?
Polyurea is a 100% solids system that is hot-sprayed by machine and cures within seconds. One-component polyurethane membranes are brush-applied and cure with air humidity; DEMCO PUR 210 1K is touch dry in 12–24 hours and fully cured in 5–7 days.
Can polyurea be applied by brush or roller?
No. The pot life of DEMCO POLYUREA /PURE and /HB is 2–10 seconds, so they can only be applied with two-component, heated-hose, high-pressure machines. For brush-applied work, liquid membranes are used.
Is polyurea UV-resistant?
DEMCO polyurea products are aromatic. In areas exposed to continuous UV light, a single coat of aliphatic polyurethane topcoat, such as DEMCO PUR 410 TOP COAT UV/S, is applied on top.
Under what conditions can it be applied?
Thanks to its fast gelling it can be applied at ambient temperatures down to -30 °C. The surface must be dry with a moisture content of no more than 4%; components A and B are brought to 25 °C before application and sprayed at 65 °C.
How much polyurea is needed per m²?
In theory 1.1 kg/m² for each 1 mm of thickness. At 2 mm this rises to 2.2 kg/m²; surface roughness and losses increase the real consumption.
Roof, car park, pool or tank: describe the area, the substrate and the thickness you expect in the quote form, and our technical team will recommend a suitable system and primer. For epoxy and polyurethane options on car park floors, see Epoxy or polyurethane?
