Cold joints occur when there's an unintended interruption in the concrete pouring process. This results in weak seams where the two layers fail to chemically bond. While most are deliberate and strengthen the structure, one, in particular, does not: the cold joint. The delayed placement prevents full integration and knitting between the concrete batches and might lead to reduced structural robustness, increased. A cold joint is a visible or structural separation that occurs when fresh concrete is poured against previously placed concrete that has already begun to set.