The theme ‘design & making UHPC bouncy ball’ is comprehensive embodiment of material properties, design creativity and fabricated skill of an UHPC element, i.e. to contest for UHPC performance (tension properties, toughness, impact resistance, etc.), for innovative design (strong but light structure, possible structures as illustrated below), for craftsmanship (ball sphericity, dimension accuracy, surface quality, etc.).
REQUIREMENTS OF UHPC BOUNCY BALL:
• Ball diameter: 200±10 mm (less 190mm / over 210mm not allowed)
• Ball weight: ≤ 6,000.0 g (overweight not allowed)
• Minimum UHPC properties: compressive strength ≥ 120 MPa, tensile strength ≥ 5 MPa and maintaining ≥ 3.5 MPa at tension strain 0.15% (meet the requirements of UT05 or higher grade by standard T/CBMF 37/T/CCPA 7-2018)
• No limitations on fiber reinforcement (types, sizes, shapes & contents), curing methods
JUDGING CRITERIA:
• Delivered ‘Design Description’ (10pt)
• Measured ball diameter accuracy (less dimension deviation - higher score, 10pt,)
• Sphericity (deviations of diameters of x, y, z direction with average diameter, 10pt)
• Surface quality (hole, smoothness, pricking the hand or not, 10pt)
• Rebound height H of 2000 mm free fall (H in centimetre = pt)
• Cracking width after free fall (10pt)
REBOUND TESTING:
The rebound height of the UHPC ball is tested on the rebound block, as illustrated below.
ABOUT THE COMPETITION:
The Co-Nele Cup: 3rd competition of design & making UHPC bouncy ball, organized by CCPA-UHPC, was held on 31-May-2024, Nanjing, China. 26 teams participated the 3rd competition, 9 teams from universities (Group Y) and 17 teams from enterprises (Group Q). A new record - rebound height of 90 cm is created in this competition. The video (4 time slower) shows UHPC ball rebound with height above 15 cm. It’s an interesting and exciting contest, attracting lot people to watch. The bouncy of UHPC ball is well presenting what UHPC can do and how high the toughness of UHPC can be obtained.
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Authors
Jun ZHAO
Jun ZHAO is the Secretary General of UHPC Branch-association of China Concrete & Cement-Based Products Association (CCPA). He graduated from Tongji University in 1985, received a master's degree in engineering from Beijing Municipal Engineering Research Institute in 1988. His working experiences since 1988 mainly engaged in R&D for cement-based materials and technical service for concrete durability, HSC, SCC, UHPC, as well as use of silica fume. He currently works for promoting the technology development, applications and standardization of UHPC at UHPC Branch-association of China Concrete & Cement-Based Products Association (CCPA).
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