Cold joints occur when a fresh concrete batch is poured against a partially hardened existing layer. As you know, concrete hardens through chemical reactions between cement aggregate, water, and air. This discontinuity occurs because the older material has passed its initial setting time, preventing a true chemical bond with the fresh mix. The full knitting together of the two batches of concrete under vibration to form a homogeneous. Based on the structural characteristics of the belt conveyor, laser ranging technology, and GNSS-RTK positioning technology, an algorithm is proposed to determine the operating status of the belt conveyor, calculate the position and area of the mixed material, and record the pouring and compaction. Explore the full spectrum of services and industries covered by B. Few defects pose a more immediate and. ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics. What is the difference between a contraction joint, isolation joint, expansion joint, construction joint, and a cold joint? A.