Delayed Casting of UHPFRC Elements

Abstract

Because of high durability and excellent material properties, innovative (thin-walled, shell) structures should be designed. Ultra - High Performance Fiber Reinforced concrete might be used for a specific application with very complex design and very complex shape. Usually, in design UHPFRC structure a reinforcement bars are replaced by a scattered reinforcement. Load bearing capacity in bending of the final shell or thin-walled structure might be influenced by many other factors, including fiber distribution, type and orientation, casting position (for example for up-side down casting) of the shell part of the structure and others. Very significant factor should be a cold joint in term of possible time delay between two batches (simulation of breakdown of the mixer, waiting time to air leakage). At the actual paper focus on an experimental program on cold joint between two batches of fresh UHPFRC poured into the thin wall and deck panels with longitudinal rib. These cold joints are caused by time delay between previous and next batch. Time between two batches differs in range of 10 – 90 minutes.