Basic Operating Procedures for Small-Scale Concrete Mixing Operations

Basic Operating Procedures for Small-Scale Concrete Mixing Operations

Whether for garden paving or small-scale masonry, the core objective of small-scale concrete mixing operations is to uniformly mix cement, sand, gravel, and water to produce fresh concrete that meets requirements. A standardized procedure not only ensures concrete quality but also guarantees operational safety and improves work efficiency. The entire process can be clearly divided into three stages: preparation, mixing, and finishing, each with its key points.

Before starting the operation, thorough preparation is the cornerstone of safety and quality. First, select a flat, firm site to place the mixer, ensuring it is stable and does not wobble. Check that all parts of the mixer are functioning properly, especially that the mixing blades are securely installed, and apply lubricating oil to parts requiring lubrication as specified. Next, prepare the dry aggregate (sand, gravel) and cement near the mixer according to the mix proportions (e.g., how many buckets of sand and gravel to mix one bag of cement), ensuring the cement is protected from moisture. At the same time, prepare sufficient cleaning water. Operators must wear protective gloves, dust masks, and goggles.

Formal mixing is the core of the process, and the key lies in controlling the order of material addition and the mixing time. Start the mixer and let it idle for a short while to confirm normal operation before adding materials. It is recommended to use the "wet-then-dry" or "pre-mixed mortar method" to reduce dust and improve uniformity: first add most of the mixing water to the mixing drum, then add all the sand and cement, mix for about 1 minute to form mortar, and finally add the aggregate and the remaining water, continuing to mix. The total mixing time, starting from when all materials are added, generally takes 2-3 minutes, until the mixture is uniform in color, without layering, and without dry lumps. During the mixing process, it is strictly forbidden to put hands or tools into the rotating drum. If admixtures need to be added, they should be dissolved in water beforehand according to the instructions before adding.

After mixing is complete, orderly unloading and cleanup are equally important. Place the wheelbarrow or hopper containing the concrete under the mixer's discharge port, and then operate the discharge handle or switch to discharge the concrete. Carefully control the discharge speed to prevent splashing. Each batch of concrete should be used as soon as possible to avoid prolonged exposure in the mixer or wheelbarrow, which could cause it to begin to harden. After each batch is unloaded, immediately add an appropriate amount of water and some aggregate to the mixing drum and start the machine to clean it, removing any residue adhering to the inner wall. After all work is completed, the mixer must be thoroughly rinsed inside and out, the site cleaned, and all tools returned to their proper places. Proper finishing not only extends the equipment's lifespan but also provides a convenient and safe environment for the next operation.