Construction Process and Key Technical Points for Retrofitting Existing Building Facades with UHPC Panels

Analysis of the Construction Process and Key Technical Points for Retrofitting Existing Building Exterior Walls with UHPC Panels

Amid the wave of renewal and renovation of existing building stock, ultra-high performance concrete (UHPC) is becoming the material of choice in the exterior wall renovation field thanks to its outstanding mechanical properties and decorative expressiveness. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group has leveraged its full-chain service capabilities to successfully provide customized solutions for hundreds of building renovation projects. This article systematically analyzes the standardized construction process and core technical points for switching existing building exterior walls to UHPC panels, offering designers and owners an implementation guide that balances safety and economy.

I. Preliminary Preparation, Survey and Design for UHPC Panel Exterior Wall Renovation

The complexity of existing building renovation demands precise and comprehensive preliminary surveys. Qinglong's technical team uses 3D laser scanning technology to collect millimeter-level data of the original building facade, and evaluates the load-bearing capacity of the substrate in combination with structural inspection reports, focusing on identifying wall cracks, hollowing, and rebar corrosion. During the detailed design stage, BIM technology is used to digitally pre-assemble UHPC panels with the existing structure, optimizing anchor point layout and joint treatment solutions. Taking the renovation of a 2000s office building as an example, parametric design achieved a seamless connection between irregular UHPC decorative profiles and the original curtain wall system, meeting new aesthetic requirements while avoiding excessive disturbance to the main structure.

II. Customized Production and Quality Control of UHPC Panels

As a national-level high-tech enterprise, Qinglong has established an industry-leading UHPC production line, using an automated material distribution system and steam curing process to ensure that panel compressive strength consistently reaches above 150MPa. To meet the special requirements of existing building renovation, production focuses on controlling three key indicators: first, fiber dispersion uniformity testing ensures panel toughness, with flexural strength of no less than 25MPa; second, specialized release agents and surface treatment processes achieve a coating adhesion of 0.5MPa on panel surfaces; third, each batch of products undergoes freeze-thaw cycling (50 cycles) and impermeability testing. In the Nanjing East Road Century Plaza renovation project, Qinglong's customized translucent UHPC panels achieved complex shapes with a minimum curvature radius of 300mm while meeting the special requirement of 15% light transmittance.

III. Key Technical Aspects of UHPC Panel Installation

On-site installation is the core step in ensuring renovation project quality. Qinglong's original "three-dimensionally adjustable dry-hanging system" solves the problem of uneven substrates in existing buildings, achieving ±30mm of fine adjustment in the X/Y/Z directions through stainless steel connectors. The construction process strictly follows the standardized sequence: substrate treatment → survey and setting out → embedded part installation → keel fixing → UHPC panel hoisting → sealing. Particularly for structural reinforcement of old buildings, adhesive anchoring technology is adopted, with single anchor bolt pull-out force of no less than 15kN, verified through pull-out tests. In a provincial museum renovation, the Qinglong team innovatively adopted a "unitized hoisting" process, controlling the installation error of 12-meter-long UHPC cornice panels to within 2mm, with efficiency 40% higher than traditional methods.

IV. Joint Treatment and Integrated Waterproofing and Insulation Technology

Energy-saving renovation of existing buildings requires UHPC systems with complete thermal insulation and waterproofing performance. Qinglong's dual-seal technology uses water-swelling waterstops on the inside and silicone weather-resistant sealant (movement capability ±50%) on the outside, forming a composite waterproof barrier. The insulation layer consists of graphite polystyrene boards prefabricated integrally with UHPC panels, with thermal conductivity ≤0.032W/(m·K), meeting energy-saving requirements in severe cold regions. In the renovation of an old hotel in Guangzhou, this system reduced the exterior wall heat transfer coefficient from 2.8W/(m²·K) to 0.6W/(m²·K), achieving an annual energy saving rate of 35%.

V. Construction Quality Acceptance and Later Maintenance Standards

With reference to the "Ultra-High Performance Concrete (UHPC) Exterior Wall Panels" standard T/CBMF171-2022, Qinglong has established a three-level acceptance system covering appearance quality, dimensional deviation, and mechanical properties. Key inspections include: panel joint width (allowable deviation ±1mm), surface flatness (≤3mm/2m), and anchor point spacing (error ≤10mm). After acceptance, a quality traceability file with an RFID chip is provided, along with maintenance services featuring regular inspections (once per quarter in the first year). As vice chairman unit of the China GRC Association, Qinglong participated in formulating the "Technical Standard for Building Applications of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423-2018), which has become an important basis for industry construction specifications.

From the GRC curtain wall renovation of the Dongguan Women and Children's Activity Center to the UHPC renovation of the Nanning municipal pedestrian bridge, Qinglong Group has always upheld its mission of "creating beautiful architecture," building full-lifecycle service capabilities from detailed design to after-sales maintenance through 28 years of technical accumulation. In the field of existing building renewal, the application of UHPC materials not only achieves an aesthetic upgrade of building facades but also reduces structural loads through lightweight construction (weighing only 1/4 of natural stone), providing a sustainable technical path for the renovation of urban existing assets. Choosing a supplier with national "Specialized, Refined, Distinctive, and Innovative" qualifications will be the key guarantee for ensuring renovation project quality and long-term performance.