Description

YHPUroof-8401 is a single-component, cold-applied, moisture-cured aliphatic polyurethane waterproofing membrane. It cures to form a seamless and durable waterproofing layer suitable for outdoor applications with heavy pedestrian traffic. YHPUroof-8401 can be applied either alone or as a top layer over a robust aromatic polyurethane base coat, such as YHPUcoat-8200 or YHPUcoat-8400.

Specifications

PROPERTIES

Description	Test Methods	Typical Values
VOC / g/L	ASTM D2369	≈180
Tensile Strength / MPa	ASTM D412	≥11
Elongation at Break / %	ASTM D412	≥350
Tear Strength / N/mm	ASTM D624	≥40
Pull-off Adhesion to Concrete / MPa	ASTM D7234	≥2.5
Shore A Hardness	ASTM D2240	≈70
Taber abrasion (750 g, 500 r, CS-10) / mg	ASTM D4060	≈35
Water Penetration Test (5 bar, 3 days)	DIN 1048-5	No Penetration
Low Temperature Flexibility (-35℃)	ASTM D522	No Cracks
Set-to-Touch Time / h	ASTM D1640	≈3

CHARACTERISTICS AND PACKAGING

Item	Data
Appearance	Viscous Liquid

Viscosity / cp	7000±2000
Color	Grey
Density / (kg/L)	1.05-1.15
Solid Content by Weight / %	85-87
Pot life / h	2
Packing Size	20 kg per metal pail

APPLICATION INSTRUCTIONS

Items	Description
Consumption*	1.25-1.40 kg / m2 for 1mm dry film
Coverage	9-11 m2/set (20kg) at 1.5mm dry film thickness
Recommended thickness	1.2-1.5 mm by 2 coats 1.0-1.2 kg / m2 / coat at 0.7-0.8 mm dry film thickness
Ambient air temperature	5 °C min / +40 °C max
Relative air humidity	<85%
Substrate temperature	5 °C min. / +40 °C max. ≥ 3 °C above dew point, beware of condensation

Application Instructions

Substrate preparation: The substrate should be clean, dry, sound, and free of all contamination, such as dirt, oil, and grease. Concrete surface defects, such as blowholes and voids, must be repaired. Concrete should be cleaned and prepared to achieve a laitance-free, open-textured surface by blast cleaning or other mechanical means, if necessary. Filling of joints and surface leveling must be carried out before coating. It is recommended to use an epoxy primer to block the cementitious substrate for coating pinhole prevention and adhesion promotion.

Detailing: Firstly, apply the coating at detailed areas such as construction joints, water outlets, and concave and convex corners. For wide cracks, use sealant to cover the surface and install fabric reinforcement between two wet coats to ensure thorough penetration and full embedment. The total thickness of the composite coating layer should be at least 1 mm.

Coating application: Apply the coating at the recommended coverage rate using a notched squeegee or trowel. Extend the coat over the entire area, including previously detailed joints and cracks. The recoat time is normally 12 to 24 hours; however, low temperature or high humidity may extend the waiting time. If slip-resistance is required, apply a 0.2–0.4mm thick wet film to the installed and cured coat, and broadcast dry aggregate onto the still-wet film. Backroll the surface to encapsulate the aggregate in the YHPUroof-8401 resin. If necessary, add an appropriate amount of pure xylene to thin the coat and facilitate rolling.

Post-treatments: Seal the coating edges with UV-resistant sealant if necessary.

Scope of Application

YHPUroof-8401 is recommended for footbridges, balconies, terraces, roof walkways, stadiums, and other outdoor waterproofing projects exposed to heavy pedestrian traffic.

FAQ

Q1: Can waterborne polyurethane be stored at temperatures below 0 degrees Celsius?

No. Waterborne coatings use water as a solvent. When stored below 0 degrees Celsius, the water in the formulation freezes, causing physical damage to the coating. Freezing may form ice crystals, which disrupt the emulsion structure of the polyurethane, leading to irreversible separation, thickening, or gelation.
Q2: What factors affect the curing speed of polyurethane?

Air temperature, humidity, mixing ratio, coating thickness, air circulation, substrate properties, and atmospheric pressure—all of these factors can affect the curing speed.
Q3: What are the factors that may affect the film-forming quality of moisture-cured one-component polyurethane？

There are several factor affect the drying speed for on-component Substrate profile; Air humidity; Substrate humidity; Coating thickness, etc.
Q4: What are the differences between aliphatic polyurethane and aromatic polyurethane?

The core difference between aliphatic polyurethane and aromatic polyurethane originates from the presence or absence of aromatic groups (such as benzene rings) in their molecular structures. This structural disparity directly leads to significant differences in their properties and application scenarios. The typical raw materials for aliphatic PU are hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. The typical raw materials fo aromatic PU are Toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), etc. Due to the absence of benzene rings, the molecular structure exhibits stronger stability against ultraviolet (UV) light, with excellent weather resistance. It is less prone to photo-oxidative degradation, maintaining color stability and resisting yellowing after long-term exposure to outdoor or light environments.
Q5: What are the uses of exposed polyurethane?

Exposed polyurethane is widely used in scenarios requiring long-term outdoor exposure or harsh environments due to its excellent weather resistance, mechanical properties, and environmental adaptability. Below are its typical application areas and technical analysis: Roof waterproofing and refurbishment, outdoor water tank, footbridges, balconies, terraces, roof walkways, parking garages, and other outdoor waterproof projects with pedestrian and/or vehicular traffic.