Rubber bladders, also known as rubber inflation cores for precast concrete hollow slabs, bridge inflation cores, and rubber inner molds, are a type of expandable and retractable internal molds made by vulcanizing high polymer rubber with high-strength fiber cloth. They are primarily used in the casting and molding process for highway bridge concrete pre-tensioned and post-tensioned beams. They are also employed in culvert drainage projects. After inflating with compressed air, the bladders expand to meet the required cross-sectional design, with inflation pressure determined by the manufacturer's specifications and should not exceed the maximum pressure. Easy to use, cost-effective, and durable, they can be reused nearly a hundred times. When not inflated, they are soft and can be folded or curled into various shapes. Upon inflation, they possess enough strength to withstand concrete pressure. They can replace traditional wood, bamboo, and steel molds, allowing for multiple uses, making them a cost-saving and construction-time-efficient concrete product accessory.
