Ready-mixed Concrete

While concrete is produced in several different forms, ready-mixed concrete is the most common.  In fact the Portland Cement Association (PCA) states that almost seventy-five percent of concrete is used as a ready-mixed form.  Referred to as RMC, the concrete is batched at a factory or batching plant rather than mixed at the jobsite.  This provides the advantage of producing precise concrete mixes as well as reducing congestion at the jobsite.  The first concrete mixing plants were built in the 1930s.

Each batch of RMC is mixed according to an exact recipe as designated by the contractor to meet the project specifications.  Once the concrete is mixed, it is quickly transported to the job site in concrete mixing trucks.   If the material is mixed during the trip to the jobsite, it is call transit-mixed or truck-mixed.  Sometimes it is partially mixed in-transit and the process completed once it reaches the placement site. 

Often with transit-mixed concrete, the water is kept separate from the cement and aggregate until it is fully mixed right before placement.  According to the Portland Cement Association, the reason behind this approach is “to avoid the problems of premature hardening and slump loss that result from potential delays in transportation or placement of central-mixed concrete.”  Also transit-mixing can be used for those times when the jobsite is a distance from the batching plant. 

The disadvantage to transit-mixing is that the cement mixer cannot carry as large of a load of concrete as it can if the concrete is already completely mixed.  Shrink-mixed concrete, which is the process of partially mixing the concrete at the plant, reduces the volume of the mixture and increases the capacity of the load.  The rest of the mixing is done during transit or at the jobsite.

The Conco Companies are a leading supplier of concrete services for the Western U.S.  We got our start in the Bay Area in 1959 by offering clients the best value on a wide range of concrete services and products.  Since that time, we have taken a leading role as one of the top concrete contractors in the region. We have four regional offices serving California, Nevada, Washington, Oregon and Colorado.

Source: cement.org/cement-concrete-basics/products/ready-mixed-concrete