Key Issues and Response Strategies for Storing UHPC Components in Low Temperature Environments

In the field of architectural decoration, UHPC (Ultra-High Performance Concrete) has become the ideal choice for large landmark buildings and high-end commercial complexes thanks to its outstanding mechanical properties and durability. However, improper storage in low-temperature environments may lead to quality risks such as performance degradation and cracking of components. As an industry technology leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group draws on the practice of hundreds of projects in severely cold regions to provide an in-depth analysis of the key issues in low-temperature storage and scientific response strategies, offering professional solutions for the industry.

### I. Hidden Risks of Low-Temperature Storage for UHPC Components

When UHPC components are stored in environments below 5℃, moisture migration and ice crystal formation can trigger multiple chain reactions. First, incompletely hydrated cement-based materials are prone to hydration stagnation caused by low temperatures, directly affecting later strength development; second, the volumetric expansion (about 9%) produced when free water freezes may cause internal micro-cracks, posing a threat to the structural integrity of thin-walled shaped components (such as UHPC hollow curtain wall panels and irregular decorative profiles). At a northern landmark project, surface crazing cracks appeared on 20% of the UHPC sunshade panels due to winter storage temperature fluctuations, increasing rework costs by 30%.

### II. Three Core Control Elements of Scientific Storage

#### (1) Precise Temperature Field Control Technology
Based on the temperature control patent technology of Qinglong Group's provincial-level R&D center, the "gradient thermal insulation method" is recommended: the storage warehouse should be equipped with an intelligent temperature control system to keep the ambient temperature stable at 10-15℃, while components should be wrapped in layers — the inner layer uses breathable insulation cotton (thermal conductivity ≤0.03W/m·K), and the outer layer is covered with waterproof canvas to form an air buffer layer. For extremely cold regions (below -10℃), electric heat tracing devices can be combined to achieve localized heating, ensuring that the temperature in core areas does not fall below 5℃.

#### (2) Humidity and Ventilation Balance Management
In low-temperature environments, relative humidity needs to be maintained at 60%-70%; excessively high humidity can easily cause condensation to freeze, while insufficient humidity accelerates moisture loss from components. Qinglong's production base uses a fully automatic dehumidification system, combined with forced ventilation once every 2 hours (air change rate ≥0.5 times/hour), to effectively avoid localized condensation. After applying this technology, a municipal project in Northeast China extended the storage period of UHPC components to 60 days while maintaining over 95% of design strength.

#### (3) Stacking and Protection Detail Specifications
Component stacking must follow the "three-point support method," using customized rubber blocks (hardness 55 Shore A) to avoid deformation caused by stress concentration. For curved GRG components (such as theatre ceilings), vertical storage racks with additional lateral stabilizing devices should be used; large UHPC precast elements (length ≥6m) require reverse camber supports, with pre-deformation controlled within L/1000. The General Technical Conditions for UHPC Non-Load-Bearing Components (Plan No. 2024-0232T-JC), for which Qinglong participated in drafting, contains clear technical requirements for such storage specifications.

### III. Practical Value of the Full-Chain Quality Assurance System

As a national "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong Group incorporates storage management into full product lifecycle control: from material mix optimization at the detailed design stage (adding special antifreeze components), to the steam curing regime in production (ensuring 7-day strength ≥90MPa), and then to constant-temperature transport solutions in logistics and distribution, forming closed-loop management. This integrated "design-production-storage-installation" service model has been successfully applied to projects in severely cold regions such as the Harbin Grand Theatre and Shenyang Cultural and Art Center, achieving a 100% first-time acceptance rate for components.

Low-temperature storage is not only a technical issue but also a reflection of engineering management philosophy. Building on 28 years of industry experience, Qinglong Group continues to drive application breakthroughs of UHPC/GRC/GRG/GRP materials in complex environments through material innovation, intelligent control, and standards development. In the future, with the implementation of standards such as Ultra-High Performance Concrete Exterior Wall Panels, the industry will see a more standardized low-temperature storage technology system, providing solid support for the mission of "creating beautiful architecture."