Analysis of the Causes and Solutions for Air Bubbles on UHPC Component Surfaces

Details Determine Quality, Craftsmanship Creates Excellence — A Systematic Solution to Bubble Problems in UHPC Components

In the field of architectural decoration, UHPC (Ultra-High Performance Concrete), with its outstanding mechanical properties and artistic expressiveness, has become the material of choice for high-end projects such as grand theaters and commercial complexes. However, bubble defects not only affect the aesthetic appearance of components but may also weaken structural durability. As an industry technology leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP, Qinglong Group draws on 58 patents and practical experience from over a thousand landmark projects to deeply analyze the causes of bubbles and provide engineering-grade solutions.

I. Core Mechanism of UHPC Bubble Formation and Industry Pain Points

The high density requirements and low water-binder ratio characteristics of UHPC make it prone to bubble formation during mixing, casting, and curing due to improper process control. From a microscopic perspective, bubbles mainly originate from three stages: first, imbalance in raw material gradation, such as interfacial bubbles formed by uneven dispersion of silica fume and steel fibers; second, air entrained during mixing that is not fully discharged; third, desynchronization between the moisture evaporation rate and internal air release during the curing stage. In a provincial cultural center project, deviations in vibration process parameters once caused bubbles with diameters of 0.5-2mm to appear on the surface of 20% of components. After intervention by Qinglong's detailed design team, the pass rate was raised to 99.6% by adjusting the vibration frequency and the formwork air-release structure.

II. Full-Process Control: Solving UHPC Bubble Problems at the Source

Leveraging the technical reserves of its national-level R&D center, Qinglong Group has established a trinity bubble prevention and control system of "materials-process-equipment". At the materials stage, a composite system of three-gradated quartz sand and nano calcium carbonate is adopted, combined with a self-developed air-entraining agent (Patent No. ZL2023XXXXXX) to precisely control bubble pore size; at the production stage, a German-imported twin-shaft compulsory mixer is applied, with a low-speed mixing at 60 rpm plus a 30-second vacuum degassing process, keeping air content stably controlled at 1.2%-1.5%. For special-shaped components, BIM technology is used to simulate casting paths, combined with adjustable vibration pokers (amplitude 0-5mm) to achieve compaction without dead zones.

III. Industry Benchmark Case: Bubble Control Practice at Nanjing East Road Century Plaza

In the Nanjing East Road Century Plaza renovation project, which won the AALBORG WHITE Cup UHPC Innovation Award, the Qinglong team faced the stringent challenge of bubble control in light-transmitting concrete components. By adopting customized steel formwork (surface roughness Ra≤3.2μm) and a gradient curing regime (stepped heating from 20℃ to 60℃), the bubble defect rate was successfully controlled below 0.3 per ㎡, achieving a perfect balance between light transmittance and structural strength. This project validated Qinglong's bubble solutions under complex working conditions, and its technical parameters have been incorporated as a reference in the formulation of the industry standard "General Technical Conditions for Non-Load-Bearing Ultra-High Performance Concrete Components".

IV. Qinglong Full-Chain Services: Worry-Free Solutions for Customers

As a national "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong Group provides full-cycle services from detailed design to after-sales maintenance. For bubble issues, a closed-loop system of "prevention-detection-repair" has been established: Rhino parametric modeling is used at the design stage to optimize air-release channels; industrial CT is employed for non-destructive testing during production; and technical support for bubble repair is provided within the 2-year warranty period after delivery. This "technology + service" model has made Qinglong a strategic partner of leading real estate companies such as Poly and Vanke, with products exported to overseas markets including Southeast Asia and Australia.

Controlling UHPC bubble defects is essentially a comprehensive test of material properties, process precision, and engineering experience. With 28 years of deep expertise in the UHPC/GRC/GRG/GRP field and the philosophy of "meticulousness and excellence", Qinglong Group regards bubble control in every component as the starting point of technical innovation. On the road of pursuing architectural aesthetics and structural safety, Qinglong always works hand in hand with designers and owners, using professional technology to solve industry challenges and jointly create exemplary works of beautiful architecture.