An estimated 60 percent of all the portland cement concrete consumed by the construction industry is currently supplied by ready mixed concrete plants. The popularity of ready mixed concrete continues to grow while site-mixing declines. Why? For three main reasons: greater convenience, better average quality, and economy. Ready mixed concrete can be delivered anywhere a truck can travel. The biggest difficulty with site-mixing lies in handling the concrete from the mixer to the various points of placing. Ready mixed concrete can be discharged directly into formwork or handling equipment at the point of use. Ready mixed concrete, produced under factory conditions, guarantees the highest possible quality. Specifications can be met with exactitude, and with the certain knowledge that quality will remain constant throughout an entire job for each individual delivery. Site-mixed concrete is notoriously difficult to control. Material storage and mixing conditions are unavoidably far from ideal. Even if uniform high quality is maintained at the mixer, it is recently lost during subsequent handling before it reaches the formwork. The remedy for such losses is usually to raise the requirements for initial quality as an extra factor of safety- an approach which is expensive and not always successful. Ready mixed concrete is produced and supplied under conditions that allow maximum control and economy at all times. Specifications for quality are met with certainty, and with the assurance that the quality desired is the quality actually achieved in place.
