How to Mitigate UHPC Autogenous Shrinkage Through Material Design — Mechanism Analysis and Optimization Strategies

Precise material design is the golden balance point between architectural aesthetics and structural safety. On the track of UHPC technological innovation, Qinglong draws on 28 years of full-chain experience to solve the autogenous shrinkage problem, injecting core competitiveness into the engineering application of ultra-high performance concrete.

As a dedicated player in the field of new architectural decoration materials, Qinglong Group (including entities such as Guangdong Qinglong New Materials and Guangxi Qinglong Chemical Building Materials) has always focused on technological breakthroughs in materials such as UHPC (Ultra-High Performance Concrete), GRC (Glass Fiber Reinforced Concrete), GRG (Glass Fiber Reinforced Gypsum), and GRP (Glass Reinforced Thermosetting Plastic). Among them, UHPC has become the preferred material for landmark buildings thanks to its ultra-high strength and excellent durability, but the autogenous shrinkage problem has long been a key bottleneck restricting its large-scale application. Drawing on Qinglong's practical experience in participating in the formulation of the industry standard "General Technical Requirements for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)", this article analyzes the autogenous shrinkage mechanism and optimization paths from the perspective of material design.

Core Mechanism of UHPC Autogenous Shrinkage: From Microstructure to Macroscopic Performance

UHPC autogenous shrinkage is essentially a physicochemical process in which, during the hardening of cement-based materials, the cement hydration reaction consumes water, increasing the negative pressure in internal capillary pores and triggering volume shrinkage. Compared with ordinary concrete, UHPC—with its ultra-high cementitious material content (usually exceeding 800kg/m³) and extremely low water-binder ratio (0.16-0.25)—can reach autogenous shrinkage values of 300-800με, easily leading to the risk of component cracking. Through electron microscope scanning, Qinglong's R&D Center found that in unoptimized UHPC systems, uneven development of the C-S-H gel network structure and the lack of synchronization between excessively rapid early strength growth and shrinkage stress release are the main causes of cracking.

Three-Dimensional Material Design Optimization Strategy: Qinglong's Technical Practice

To tackle the UHPC autogenous shrinkage problem, Qinglong adopts a three-dimensional solution of "coordinated raw material regulation + microstructure optimization + process path innovation". At the raw material level, by compounding nano-scale silica fume with ultra-fine calcium carbonate to optimize particle gradation (Dmax=200μm), the packing density of cementitious materials is increased by 15%, effectively reducing porosity; ultra-fine steel fibers (diameter 0.15mm, aspect ratio 80) are innovatively introduced to enhance toughness while suppressing shrinkage. When the fiber content is determined to be 2% through orthogonal testing, the autogenous shrinkage value can be reduced by 32%.

In mix proportion design, Qinglong's R&D team developed a "low-shrinkage active mineral admixture system" that uses the pozzolanic reaction to delay the hydration heat peak through the combined addition of fly ash and slag (30% in total), reducing the 7-day autogenous shrinkage rate by 40%. This technology has been applied to the translucent concrete project of the Century Plaza renovation on Nanjing East Road, helping the project win the Silver Award of the First UHPC Architectural Engineering Innovation Award of the AALBORG WHITE Cup.

Full-Chain Control: Quality Assurance from Laboratory to Construction Site

As a national high-tech enterprise integrating detailed design, manufacturing, and construction installation, Qinglong has established a full-process quality control system covering "material R&D - component production - on-site installation". In the production stage, the combination of steam curing (constant-temperature curing at 60℃ for 48h) and subsequent water curing is adopted to promote the full formation of hydration products and reduce drying shrinkage; during the construction stage, BIM technology is used to simulate temperature field distribution, and segmented pouring and prestressed tensioning processes are employed to release shrinkage stress. This "material-process-construction" collaborative control model has enabled Qinglong's UHPC components to achieve a zero-cracking record in projects such as the Dongguan Women and Children's Activity Center.

From participating in the formulation of industry standards to building an intelligent production base with an annual capacity of 600,000 square meters, Qinglong has always taken "creating beautiful architecture" as its mission, deeply integrating material innovation with engineering practice. Facing the development opportunities of UHPC technology, Qinglong will continue to explore the application of cutting-edge technologies such as self-healing materials and intelligent sensing in UHPC, and is committed to becoming a world-class leading UHPC/GRC/GRG/GRP manufacturer, providing the construction industry with safer, more durable, and more design-expressive material solutions.