What Effects Can Surface Acid Pickling Treatment of UHPC Panels Achieve and Analysis of Its Working Mechanism

Chemical reactions in the microscopic world forge a macroscopic leap in quality for UHPC panels — how does the acid pickling process empower ultra-high performance concrete?

Amid the wave of innovation in building materials, UHPC (Ultra-High Performance Concrete) has become the “new favorite” of high-end buildings such as grand theaters and convention and exhibition centers, thanks to its outstanding mechanical properties and aesthetic expressiveness. As an industry leader with 28 years of deep expertise in the UHPC/GRC/GRG/GRP materials field, Qinglong Group has always been committed to unlocking material potential through process innovation. This article provides an in-depth analysis of the core value and working mechanism of acid pickling treatment on UHPC panel surfaces, offering a professional reference for designers and owners.

### I. UHPC Panel Acid Pickling: From “Industrial Process” to “Quality Revolution”

Acid pickling is not simply surface cleaning; it is a key process that achieves microstructural optimization and performance upgrades through a controlled chemical reaction between an acid solution of a specific concentration and the UHPC surface layer. Qinglong Group incorporates acid pickling process parameters as early as the detailed design stage, ensuring quality control across the entire chain from manufacturing to construction and installation. Compared with traditional grinding, acid pickling allows more precise regulation of surface porosity, enhancing decorative effects while laying the foundation for the adhesion of subsequent coatings — this is precisely Qinglong’s technical practice of its mission to “create beautiful architecture” as a national high-tech enterprise.

### II. Three Core Effects: Redefining the Performance Boundaries of UHPC Panels

**1. Artistic Reshaping of Surface Texture** During acid pickling, the acid solution selectively dissolves the cement hydration products in the UHPC surface layer, forming uniformly distributed microscopic pits and textures. This “controlled corrosion” gives the panels a warm, subtle texture similar to natural stone, perfectly matching the aesthetic requirements of commercial complex facades. Through large-scale practice with an annual production capacity of 600,000 square meters, Qinglong’s production base has achieved customized production of 12 surface effects ranging from matte to imitation lychee finish, meeting the personalized design demands of landmark buildings.

**2. Invisible Reinforcement of Mechanical Properties** At the microscopic level, acid pickling removes weak calcium hydroxide crystals from the surface layer and exposes the dense internal C-S-H gel network, increasing the panel’s surface hardness by 15%-20%. In projects such as the renovation of Century Plaza on Nanjing East Road, Qinglong’s acid-pickled UHPC translucent panels achieved a tested flexural strength of 22MPa, far exceeding industry standards, confirming the quality commitment of “meticulousness and relentless pursuit of excellence.”

**3. Multi-Dimensional Enhancement of Durability** The honeycomb-like structure formed by acid pickling can store protective coatings, enhancing impermeability and weather resistance. According to the “General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC),” which Qinglong participated in formulating, acid-pickled UHPC panels exhibit superior freeze-thaw cycle resistance in accelerated aging tests, making them particularly suitable for overseas projects in extreme climate regions such as Saudi Arabia.

### III. Working Mechanism: Chemical-Reaction-Driven Microscopic Restructuring

Taking the hydrochloric acid–oxalic acid composite acid system as an example, its working mechanism can be divided into three stages: first, H⁺ ions penetrate and dissolve the surface-layer Ca(OH)₂, forming complexes of Ca²⁺ and Cl⁻; next, oxalate ions combine with Ca²⁺ to form sparingly soluble calcium oxalate crystals that fill the surface pores; finally, the reaction is terminated through precise pH regulation (Qinglong’s patented technology), locking in the optimized microstructure. This process requires strict control of the acid concentration (3%-8%) and treatment time (15-45 minutes), and the intelligent control system at Qinglong’s R&D center can achieve temperature precision of ±0.5°C, ensuring batch-to-batch stability.

### IV. Full-Chain Empowerment: Value Transfer from the Laboratory to the Construction Site

As a professional manufacturer integrating detailed design, production, and construction installation, Qinglong has incorporated the acid pickling process into its BIM collaborative workflow: at the design stage, parametric models are used to simulate acid pickling effects; during production, automated spraying equipment ensures uniformity of treatment; during installation, specialized anchors are used to avoid damaging the optimized surface structure. This full-chain control capability has enabled Qinglong UHPC panels to achieve a perfect translation from design drawings to as-built results in overseas projects such as the Petronas Twin Towers in Malaysia.

From microscopic chemical reactions to macroscopic engineering applications, the acid pickling of UHPC panels is both an upgrade in material performance and a breakthrough in process aesthetics. With 28 years of industry experience as its foundation, and through technological innovation and standard-setting (participation in multiple industry standards including “UHPC Exterior Wall Panels”), Qinglong Group continues to provide designers with material solutions where “what you envision is what you get.” On the road toward architectural aesthetics and engineering quality, the acid pickling process is becoming the key code for UHPC materials to empower “beautiful architecture.”