What Is the Connection Solution for UHPC Exterior Walls and Door and Window Openings?

The connection between UHPC exterior walls and door/window openings is a critical node in curtain wall systems for waterproofing, airtightness, thermal insulation, and aesthetics. Its core lies in following the principle of "structural waterproofing first, material sealing second, and unobstructed drainage paths" to achieve multiple lines of defense. Qinglong Group has developed a mature, standardized solution combining an "UHPC sub-frame system" with "multi-layer sealant joint sealing". In the Nanning Wuxiang China Resources MixC One project, through precise alignment between the aluminum alloy sub-frames pre-embedded on the sides of UHPC panels and the door/window frames, combined with multiple sealing strips and weather-resistant sealant, we achieved an extremely high level of waterproofing performance, verified by water spray testing with no leakage whatsoever.

Structural Design: Installing Waterproof Flashing and Drainage Channels

This is the most effective waterproofing measure. On the UHPC profiles or panels at the top edge of door/window openings, concealed aluminum alloy or stainless steel waterproof flashing should be designed to direct any infiltrating rainwater outward. At the bottom of the opening, ensure that weep holes are provided to discharge any small amount of accumulated water. Sufficient installation space (typically ≥20mm) should be reserved between the UHPC and the door/window frame to allow for internal sealing and installation of insulation materials.

Sealing System: Multiple Layers of Material Sealing Form a Tiered Line of Defense

1) First layer (exterior): Apply weather-resistant silicone sealant at the exterior joint between the UHPC and the door/window frame. This is the first barrier against wind and rain, and the sealant joint should be full and continuous. 2) Second layer (middle): On the inner side of the UHPC or on the pre-embedded sub-frame, install a compressed sealing strip (such as an EPDM strip) pressed tightly against the door/window frame, forming an airtight and watertight line of defense. 3) Third layer (interior): On the interior side, interior sealant can be applied to further improve airtightness. Multiple layers of sealing form a three-dimensional defense system combining "channeling, blocking, and draining".

Thermal Insulation Continuity: Blocking Thermal Bridges

Connection areas are high-risk zones for thermal bridging. It is necessary to ensure that the insulation of the door/window frame effectively connects with the wall's insulation layer to avoid creating breakpoints. The gaps between the UHPC and the door/window frame should be filled with elastic insulation materials (such as foamed polyethylene rods). Qinglong's UHPC system can integrate insulation layers, achieving the integration of insulation and decoration, thereby simplifying the insulation transition treatment at door/window openings.

Precision Control and Tolerance Absorption

The fineness of the connection depends on production and installation precision. The dimensions of UHPC openings must precisely match the door/window dimensions. Adopting a pre-embedded sub-frame system can better absorb civil construction opening deviations and installation deviations. Qinglong uses BIM models for integrated design to ensure dimensional coordination among UHPC, doors/windows, and the structure, completes sub-frame pre-embedding in the factory, and performs direct alignment installation on site, greatly improving installation precision and waterproofing reliability.