Backed Hdpe Sheet Waterproofing Pre Laid For Underground Engineering

Backed Hdpe Pre-laid Waterproof Material For Underground Engineering

Product Description

One‑side backed & one‑side sand‑surfaced HDPE self‑adhesive film waterproof membrane is a pre‑laid reverse‑bonding non‑asphalt polymer waterproof material made of HDPE substrate. One side is backing layer, the other side is sand‑coated self‑adhesive layer. During construction, the sand‑surface faces post‑poured concrete for physical interlocking and firm bonding to block water channeling. The backing layer faces bedding course to improve dimensional stability and tear‑resistance, reducing damage on site. It is specially designed for underground pre‑laid waterproof projects.

Product Advantages

1. Pre‑laid reverse‑bonding and anti‑water‑channeling. Sand surface interlocks with post‑poured concrete, integrating waterproof layer with concrete structure.
2. Double‑sided protection structure. Sand surface guarantees concrete bonding performance; backing layer improves toughness and tear‑resistance to reduce construction damage.
3. High puncture resistance and tensile strength. HDPE substrate resists piercing from steel bars and gravel.
4. Cold‑applied construction without open flame. Suitable for damp substrate, safe for confined underground space.
5. Good underground corrosion resistance. Non‑asphalt material resists acid, alkali and underground soil‑water erosion for long‑term service life.
6. Shorten construction period and cut overall cost. Partial cement mortar protection layer can be omitted to simplify working steps.

Construction Method

1. Substrate Treatment: Level bedding surface, remove gravel and sharp protrusions. Damp substrate is acceptable, no standing water.
2. Membrane Laying: Lay membrane with sand‑surface towards concrete structure, backing side down against bedding layer. Spread according to layout lines and align lap edges.
3. Lap Joint Treatment: Remove release film at laps and press self‑adhesive layers tightly. Apply reinforcement layers at internal and external corners.
4. Edge Fixing: Seal laps and membrane ends with pressure strips to avoid displacement and blistering.
5. Finished‑product Protection: Prevent puncture by sharp objects after laying. Proceed to steel bar binding timely.
6. Concrete Pouring: Pour post‑poured concrete directly onto sand‑surface side to realize interlocking pre‑laid reverse‑bonding effect.

Note: For underground pre‑laid use only. Exposed application and hot‑melt operation are forbidden.