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Shotcrete performance requirements
Published in Dudley Robert (‘Rusty’) Morgan, Marc Jolin, Shotcrete, 2022
Dudley Robert (‘Rusty’) Morgan, Marc Jolin
The following types of concrete surface preparation were used:Hydrodemolition;Sandblasted;Jackhammered;Jackhammered and sandblasted;Grinding.The prepared concrete surfaces were predampened prior to shotcrete application. Extensive experience in bond testing in the laboratory and in the field has demonstrated that the optimal moisture condition for the substrate concrete (and for that matter substrates such as masonry and rock) for maximizing bond strength is the Saturated Surface Dry (SSD) condition. If the substrate surface is excessively wet (has free surface water on it) at the time of shotcrete application, this can result in a high water/cement ratio at the critical bond interface and a substantial reduction, or even loss of bond strength, altogether. Conversely, if the substrate surface is excessively dry at the time of shotcrete application, water can be sucked out of the freshly applied shotcrete and the consequent desiccation at the critical bond interface can reduce bond strength. Hence the importance of having the substrate in an SSD condition at the time of shotcrete application.
Repair and protection (A) – mechanical methods
Published in Brian Cherry, Green Warren, Corrosion and Protection of Reinforced Concrete, 2021
There is a growing use of shotcreting (guniting) for concrete repairs. One of its main advantages is that large area and large volume repairs can be undertaken including overhead without the need for formwork. However, the same care is required in removing defective concrete, providing a clean substrate, and cleaning the bars as with other types of repairs. The defective or contaminated concrete is removed with percussive tools or hydrodemolition. The steel is cleaned with high pressure water or wet abrasive blasting.
Rehabilitation works of Minab Dam spillway
Published in Jean-Pierre Tournier, Tony Bennett, Johanne Bibeau, Sustainable and Safe Dams Around the World, 2019
M. Sadri Omshi, A. Amini, F. Manouchehri Dana
Although, concrete removal of spillway could be done using traditional method of manual demolition or chipping hammers, a cutting-edge hydrodemolition technology was considered to be utilized due to heavy reinforcement of wall and floor slab and its other benefits.
Strengthening of the Riddes Viaduct Through UHPFRC-Based Rehabilitation
Published in Structural Engineering International, 2023
Hammad El Jisr, Lionel Moreillon, Philippe Menétrey
The viaduct was maintained in an unpropped state during the rehabilitation process. Installation of the reinforcing layer was conducted by first milling and removing the pavement and waterproofing. This was followed by hydrodemolition of the entire wearing surface to a thickness of 20 mm in order to remove the damaged concrete and create a rough surface for bonding the UHPFRC. Near the curbs, grooves were made to bond the UHPFRC layer to the existing reinforcement. The UHPFRC was laid by hand and directed towards grooves made in the deck slab (see Fig. 9).