The slightest concrete-mixing mishap can render an entire batch of concrete useless. But since ready-mixed concrete is batched in a factory using a specific formula, it reduces the instances and costs associated with bad concrete mixtures. Ready-mixed concrete eliminates the need for construction sites to find space to store the bulk ingredients needed to mix concrete on site. And the widespread availability of ready mixed concrete allows concrete finishers to do their jobs faster because they don't have the added chore of mixing concrete.
There are three commonly used mixing methods for ready mixed concrete--central, transit, and shrink-mixed. Central-mixed is completely mixed in the factory. During transit-mix, the ingredients are added at the factory and mixed by the mixing truck en route to the construction site. And shrink-mixed is where the concrete is partially mixed at the plant and mixing is finished either en route or on the job site.
Homeowners and concrete finishers can also purchase ready mixed concrete in bags that range from 40 to 80 pounds at home improvement stores. The ingredients in the bagged concrete are already measured. All that's needed to complete the mixture is water, and a sturdy mixing container such as a mortar tub.
Once the ready mix concrete is ordered, the mixture is batched and delivered to the job site in a cylinder shaped cement mixer truck. The concrete is then unloaded off the truck into the designated area while the concrete finishers simultaneously spread it with masonry pacers and other tools to prevent clumping.
Common ingredients in a concrete mixture include cement, sand, water, and aggregates. Additives such as calcium, to help the concrete set faster in the winter, and fiber to add strength and minimize cracking can be added per contractors requests.
Ready mixed concrete can be used for both residential and commercial purposes. But sometimes concrete trucks won't fit into tight residential spaces. In cases such as this, the mixer truck will park as close to the designated area as possible while a pump truck feeds the concrete through a hose that's long enough to reach the area. If there is no pump truck available, concrete finishers will wheelbarrow the ready mixed concrete to the designated area by hand.