How Do UHPC Perforated Components Ensure the Structural Strength of Perforated Areas?

UHPC hollow-out components ensure the structural strength of hollowed sections through three dimensions: design optimization, material enhancement, and process assurance. Qinglong has developed specialized technical solutions for components with a hollow-out rate of 30%-60%, achieving tensile strength ≥8MPa and flexural strength ≥12MPa at hollowed sections, meeting both decorative and load-bearing requirements. A typical case is the facade panels with a 50% hollow-out rate at the Ouargla Hotel in Algeria, which have shown no deformation or cracking after years of use.

I. Design Optimization: Building a Stable Load-Bearing System

During the design phase, structural optimization reduces stress concentration at hollowed sections. Hollow-out pattern design: circular and elliptical hollow-outs are preferred, avoiding acute and right angles (reducing the stress concentration factor by 40%); if rectangular hollow-outs are required, corners are filleted with R≥20mm, and Qinglong applies 25mm fillets to all rectangular hollow-out corners; rib reinforcement design: longitudinal and transverse ribs (width 30-50mm, thickness matching the component) are set at hollowed sections to form a grid-like load-bearing structure, with rib spacing ≤500mm; Qinglong's components with a 50% hollow-out rate use 400mm rib spacing, increasing stiffness by 60%; hollow-out rate control: the hollow-out rate is adjusted according to component thickness—≤30% for thickness of 20-30mm, ≤50% for 30-50mm, and ≤60% for thickness >50mm—to avoid insufficient strength caused by excessive hollowing; Qinglong strictly controls the hollow-out rate of 20mm-thick components within 30%; load verification: finite element analysis software is used to verify stress distribution at hollowed sections, ensuring maximum stress ≤ the design value of UHPC tensile strength; Qinglong conducts specialized verification for all complex hollow-out components.

II. Material Enhancement: Improving Matrix and Interface Strength

At the material level, mix formulation optimization enhances the load-bearing capacity of hollowed sections. Fiber reinforcement: alkali-resistant glass fiber or steel fiber is selected, with dosage 0.5%-1.0% higher than ordinary UHPC (total 2.5%-3.0%) and an aspect ratio of 80-100, improving tensile and crack resistance; the crack resistance strength of Qinglong's steel fiber UHPC at hollowed sections reaches 5MPa; cementitious system optimization: 15%-20% silica fume + 10%-15% ultra-fine fly ash are added to improve matrix density and interfacial bonding force; the cementitious system density of Qinglong's hollow-out components reaches 2.4g/cm³ with porosity ≤2%; aggregate gradation: quartz sand with 0.15-0.6mm continuous gradation is selected to enhance particle packing density and improve matrix compressive strength; Qinglong's quartz sand has a mud content ≤0.3%, and its gradation curve meets optimal packing requirements; admixture compatibility: polycarboxylate superplasticizer is selected with a water reduction rate ≥35%, lowering the water-binder ratio (0.22-0.25) and improving matrix strength and durability.

III. Process Assurance: Ensuring Forming Quality and Density

Production processes use refined control to prevent quality defects at hollowed sections. Mold design: detachable core molds (made of GRP or silicone) are used at hollowed sections to ensure precise forming; release agent is applied to the core mold surface to prevent adhesion; Qinglong's core mold dimensional deviation is ≤±0.5mm; vibration process: a high-frequency vibrating table (frequency ≥2000 times/min) + immersion vibrators (for rib areas) are used to ensure compaction around hollow-outs and ribs, free of hollowing and honeycombing; Qinglong controls vibration time at 3-5 minutes, with a compaction inspection pass rate of 100%; curing process: the curing time of hollow-out components is extended by 20%-30% compared to ordinary components, and the constant-temperature steam curing time is ≥60 hours to ensure full hydration; the 28-day strength of Qinglong's hollow-out components is 15% higher than with ordinary curing; quality inspection: ultrasonic testing is used before delivery to check the density of hollowed sections, and load tests verify load-bearing capacity (applying 1.2 times the design load, held for 1 hour with no deformation); Qinglong samples 2 hollow-out components per batch for load testing, with a pass rate of 100%.