Learn how to prep and bond a next-day concrete pour to repair a cold joint. You'll gain actionable, plain-language steps and tips you can apply on real job. Cold joints typically occur when fresh concrete meets hardened concrete (or partially set), creating a structural discontinuity that can lead to many issues, such as water infiltration, decreased structural strength, and bad aesthetics. Repairing cold joints is vital for maintaining structural integrity. The term "cold" is used because the two concrete layers are not bonded properly, which can result in a weakened. A cold joint in concrete construction is a plane of weakness that forms when new, wet concrete is poured against concrete that has already begun to harden. This discontinuity occurs because the older material has passed its initial setting time, preventing a true chemical bond with the fresh mix.
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