Is UHPC Shrinkage Rate High? Analysis of Influencing Factors and Improvement Measures

The "Micro-Code" of Building Materials: Scientific Analysis and Industry Practice of UHPC Shrinkage Rate

In the field of contemporary architectural decoration, Ultra-High Performance Concrete (UHPC) is becoming the new favorite of high-end projects such as grand theaters and commercial complexes thanks to its excellent mechanical properties and artistic expressiveness. However, the shrinkage characteristics of the material have always been a core concern in the engineering community—when millimeter-level deformation meets hundred-meter-level building scale, how to precisely control the shrinkage rate directly relates to the safety and durability of the project. As an industry technology leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP, Qinglong Group will start from the essence of the material and systematically analyze the influencing factors of UHPC shrinkage rate and engineering solutions.

The "Dual Character" of UHPC Shrinkage Rate: Material Properties and Engineering Challenges

The shrinkage rate of UHPC is not a single value but the result of multiple shrinkage mechanisms working together. Compared with traditional concrete, UHPC exhibits more significant early autogenous shrinkage due to its ultra-high cementitious material content (usually over 800kg/m³) and extremely low water-binder ratio (0.15-0.25), typically reaching 200-500με, while long-term drying shrinkage is effectively controlled thanks to its dense microstructure. This "rapid first, then gradual" shrinkage characteristic poses severe challenges to the construction and splicing of large components such as UHPC exterior wall cladding panels and landscape sculptures. In a landmark project, unoptimized UHPC sunshades once developed surface cracks due to concentrated shrinkage stress—a typical case of ignoring material shrinkage characteristics.

Four Core Influencing Factors: Key Variables from Laboratory to Construction Site

Material composition determines the shrinkage baseline. The type and amount of cement are the "source switch" of shrinkage; using low-alkali cement can reduce expansion and shrinkage caused by alkali-aggregate reaction. Although active admixtures such as silica fume can improve strength, excessive addition will aggravate autogenous shrinkage. Qinglong R&D Center found through orthogonal tests that when silica fume content is controlled at 20-25%, the optimal balance between strength and shrinkage can be achieved. Fiber content acts like "micro reinforcement"; when basalt fiber content reaches 2%, the shrinkage rate can be reduced by 15-20%. This technical parameter has been applied in the translucent concrete project of the Century Plaza renovation on Nanjing East Road.

The curing regime is the "regulator" of shrinkage control. Standard curing (20℃, 95% humidity) can delay early shrinkage, but engineering practice calls for more innovative solutions. Qinglong's production base in Nanning, Guangxi adopts a "gradient curing method": first steam curing at 60℃ for 4 hours to stimulate strength, then transferring to a constant temperature and humidity environment at 25℃ for 72 hours, keeping the 28-day shrinkage rate of UHPC components stably within 300με, improving efficiency by 40% compared to conventional curing.

Construction technology can amplify or buffer shrinkage effects. The timing of formwork removal directly affects restrained shrinkage. Qinglong simulates the shrinkage curves of different components through BIM technology and establishes a "strength-shrinkage dual indicator" removal standard to ensure that the elastic modulus has developed to over 80% at demolding. For the composite installation of hyperbolic GRG ceilings and UHPC components, three-dimensional laser scanning positioning technology is used with 0.5-1mm shrinkage joints reserved, successfully solving the splicing precision challenges of the Dongguan Women and Children's Activity Center project.

Environmental factors constitute external challenges. High temperature and dry environments accelerate water evaporation. In a project in Saudi Arabia, Qinglong innovatively adopted a "pre-wetting installation method": soaking UHPC components in 5℃ water for 24 hours, then covering them with water-retention film for 14 days of curing after installation, reducing the on-site shrinkage rate by 25%. This practice confirms the importance of environmentally adaptive design.

Qinglong's Full-Chain Solution: A Technical Closed Loop from Material R&D to Engineering Implementation

Material innovation builds the first line of defense for shrinkage control. As a participant in formulating the industry standard "General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)", Qinglong has developed a "low-shrinkage UHPC formula" that controls the autogenous shrinkage rate below 250με through the synergistic effect of composite mineral admixtures, while flexural strength remains above 15MPa. This technology has been applied in multiple metro utility tunnel projects in China.

Digital design achieves shrinkage pre-control. Using the Rhino+Grasshopper parametric platform, Qinglong engineers can simulate shrinkage deformation under different working conditions and automatically generate processing drawings with pre-deformation compensation. In a commercial complex project, by presetting a shrinkage compensation value of 3‰ in advance, the joint error of 12-meter-long UHPC decorative lines after installation did not exceed 2mm.

Innovative construction methods guarantee engineering quality. For the hoisting of large UHPC components, Qinglong pioneered the "stress release installation technology": using adjustable elastic supports, components are allowed to slowly release 50% of shrinkage stress in a restrained state before rigid fixing. This process enabled the UHPC curtain wall system of an airport project to reach the industry-leading flatness level of 1mm/2m.

Full life-cycle service system. From shrinkage simulation analysis in the detailed design stage, to curing parameter optimization in manufacturing, to on-site monitoring during construction and installation, Qinglong has established a quality traceability system covering the entire life cycle of UHPC/GRC/GRG/GRP products. Through implanted RFID chips, the shrinkage changes of components can be monitored in real time, providing data support for after-sales maintenance—this is a demonstration of the technical strength of a national high-tech enterprise.

In the field of new architectural decoration materials, precise control of material properties is the cornerstone of engineering quality. As a leading UHPC/GRC/GRG/GRP manufacturer, Qinglong Group has always taken "creating beautiful architecture" as its mission, transforming 28 years of industry experience into the driving force of technological innovation. Whether it is millimeter-level shrinkage rate control or the precise realization of complex shapes, Qinglong is committed to providing designers and owners with architectural decoration systems that combine safety, durability, and aesthetic value through full-chain solutions. In the future, with continuous breakthroughs in material technology, UHPC will surely shine in more landmark buildings, and scientific understanding and systematic control are the key to unlocking its application potential.