How to Fix Joint Leakage on UHPC Curtain Walls? Waterproofing Solutions

1. Root-Cause Diagnostics — Three Triggers

(a) Embedment coating failure: UHPC element permeability exceeds P20, but uncoated embedments corrode and expand, squeezing the sealant layer into hidden cracks — visible as irregular rust stains on the facade, unfixable by surface re-caulking.

(b) Joint design / construction mismatch: Joints narrower than 15 mm, or inadequate surface grinding before sealing, leave sealant adhesion failing under thermal cycling.

(c) Aging maintenance gap: Neutral sealant outdoor life is 5-8 years against UHPC's 50-year design life. Without periodic joint tests, aging cracks open direct leak paths.

2. Layered Rectification

Surface-only leak (aged sealant): strip failing sealant, clean UHPC faces with dedicated cleaner, re-caulk with weather-resistant sealant for UHPC substrate, 72-hour cure protected from water and stress.

Mid-level leak (embedment corrosion): dismantle surrounding UHPC elements, replace embedments with anti-corrosion S316 stainless steel, add back-side waterproof backing layer before re-sealing.

Severe systemic leak (supertall all-joint failure): mark every leak point across the facade, re-engineer the joint system with a 'back-side diversion + surface sealing' double-defense, then validate with a closed-water test.

3. Long-Term Prevention — Front-Load the Waterproofing

Reserve thermal-expansion clearance and select compatible sealants during design; specify anti-corrosion embedment treatments. Control panel-joint surface flatness deviation within 0.5 mm during production. Run joint adhesion pull-tests on every sealant segment during installation.

FAQ

Q: UHPC curtain wall leaking right after construction?
A: Most likely sealant interface cleaning was incomplete or air bubbles formed during caulking. Strip and re-apply.

Q: Coastal UHPC waterproofing materials?
A: Salt-fog-resistant S316 stainless embedments + neutral weather-resistant sealant rated for salt fog. Avoid carbon-steel embedments and generic sealant.

Q: Aged UHPC curtain wall — full facade rebuild?
A: No — survey all leak points first, then layer the rectification by severity. Full-system replacement only when the entire joint system has aged out.

About Qinglong GRC — Guangdong Qinglong Construction Engineering Co., Ltd. Founded 1997 (28 years). 50+ patents. Integrated R&D, design, production, sales and construction. Contact: Mr. Song, +86 139 0259 7531. Address: 302 Card, No. 22 Dongming Road, Shiqi District, Zhongshan City.