QAQC in Construction

Major factor should be considered when placing the concrete on-site delivered from the batching plant/Mixing plant, Many and varied below:- Ambient temperature (The Weather During the Casting Time) Specification for the Mix Design Sub-grade Condition Type of Installation (Lean, Structure, Column, Beam, etc.) Form Securement Type of reinforcement Sufficient personnel capable of placing the concrete. Pouring Rate Height of Free Fall of Concrete must not be more than 1.2 m. Avoid Cold Joints

Common Concrete Pouring Issues 1. AIR LOSS: During concrete pouring, air loss can cause problems. Several factors lead to this, such as long vertical drops, high initial slump, increase in pressure, or drop in exit. For every 1% decrease in air, strength decreases by 4-5%. You can fix this problem by adding a gate at the end of the pump line for restriction. It also helps to keep the boom in an upward or horizontal position as much as possible. If this can’t be done you can put multiple 90 degree elbows into the line to slow down concrete, minimizing the straight dropout. 2. BUG HOLES: Bug holes are evident by a small void on the outside of formed concrete surfaces. These come from poor application of form release agents to form-work or completely forgoing their use entirely. It can also come from stiff or sticky concrete mixtures. This can also be caused by poorly placed internal concrete vibrators. To solve the problem of bug holes, make sure release agents are applied...