What is the typical compressive strength of a 30mm thick UHPC panel?

The compressive strength of 30mm thick UHPC panels is a key indicator of their performance as structural or high-performance decorative components. For high-quality UHPC materials, thickness itself is not the main factor limiting compressive strength; the strength primarily depends on the material mix proportions and curing regime. Qinglong Group's internal control standards and extensive field test data show that 30mm thick UHPC panels produced with the standard steam curing process typically achieve a stable cube compressive strength in the range of 150MPa to 200MPa. For example, 30mm thick UHPC components used at critical load-bearing joints in the Hainan International Convention and Exhibition Center recorded an average measured compressive strength of 178MPa, fully meeting the stringent requirements of the super-large roof system. This value is 5-6 times that of ordinary C30 concrete and approximately twice that of C80 high-performance concrete.

Material Mix Proportions Are the “Genetic” Determinant of Strength

Achieving ultra-high strength above 150MPa relies on mix design guided by the scientific “particle packing” theory. In Qinglong's formulation, the total amount of cementitious materials (cement + silica fume) typically exceeds 800kg/m³, with silica fume accounting for 20%-25% to fill the smallest pores. The water-binder ratio is strictly controlled within the extremely low range of 0.18-0.22, with workability ensured through polycarboxylate superplasticizers. The aggregate is perfectly graded quartz sand with a maximum particle size generally below 1mm. At the micro level, this mix proportion forms an extremely dense matrix structure with minimal defects.

The Steam Curing Regime Is the “Catalyst” for Strength Development

For 30mm thick panels, proper curing is crucial. Qinglong adopts a standardized steam curing curve of “temperature rise – constant temperature – temperature drop”. Components are typically cured for 24-48 hours in a saturated steam environment at 60-90℃. The hot, humid environment greatly promotes the secondary hydration reaction between active SiO₂ (from silica fume) and Ca(OH)₂, a cement hydration product, generating more C-S-H gel with a low calcium-silica ratio, high strength and high stability. This is the key process step for UHPC to achieve early ultra-high strength. After curing, UHPC can reach a strength of over 120MPa within 1 day.

The Effect of Thickness on Strength and the Size Effect

Theoretically, under conditions of homogeneous materials and adequate curing, thickness has little effect on compressive strength. In practice, however, attention must be paid to the “size effect”: during the curing of thicker components, there may be slight gradients in internal temperature and hydration progress compared with the surface, requiring process adjustments to ensure uniformity. By optimizing the curing regime (such as controlling the heating rate and ensuring sufficient constant-temperature duration) and through online temperature and humidity monitoring, Qinglong ensures that the performance of 30mm and even thicker components is uniform across the entire cross-section.

The Balance Between Strength and Toughness

It is worth noting that compressive strength is not the only indicator. The steel fibers or high-performance synthetic fibers incorporated into UHPC contribute mainly to flexural strength, toughness and impact resistance. For 30mm thick panels, the fibers can effectively prevent the propagation of internal micro-cracks; even under extremely high pressure, failure exhibits a certain degree of pseudo-ductility rather than the sudden explosive spalling typical of ordinary high-strength concrete, which greatly enhances safety in use. Qinglong UHPC's flexural-to-compressive strength ratio (flexural strength/compressive strength) can reach 1/10 to 1/8, demonstrating excellent toughness characteristics.

Therefore, achieving compressive strength above 150MPa in 30mm thick UHPC panels is a mature demonstration of modern materials technology. Through precise mix design and rigorous process control, Qinglong Group ensures that every thick panel leaving the factory possesses outstanding and stable mechanical performance.