The pumping of concrete has become one of the fastest growing methods of transporting and handling at the job site. Pumping is a point to point delivery system in which concrete is moved under pressure through rigid pipe, flexible hose or a combination of both to its final destination in the forms with little necessity for further handling of the mix. Hence, with pumping there is less chance for segregation. There are a number of other advantages in pumping concrete that should be considered when evaluating job site transporting and handling methods. The use of pumps can eliminate or greatly reduce the need for access roads, scaffolding, and other concrete handling equipment. Hoists and cranes are freed to handle other construction materials concurrently with concrete placing. Where tower cranes are being used the use of pumps permits them to be smaller and to speed job completion because other crafts can work relatively unhampered by concrete operations. Furthermore, concrete may be pumped vertically, horizontally or around corners, and the delivery lines can be run over, under or around obstruction and through windows or other small openings. No other method is as adaptable as pumping for transporting concrete into confined areas or under adverse conditions like inclement weather. Cases have been reported in which concrete pumped through aluminum pipeline has exhibited a decrease in strength. This can be caused by reaction of abraded aluminum particles with the alkalies in the portland cement, resulting in the formation of hydrogen gas and consequent increase in volume of the fresh concrete. This has the same strength reducing effect on the concrete as an excessive amount of entrained air. Concrete pumped through pipelines made of other materials has not shown this detrimental effect.