Document Archives

Use of Lightweight Concrete in Railroad Work

• ID:

  353

• ESCSI:

  4000.013

• Author:

  Hutchens, Harold R.

• Publication Name:

  Masonry

• Type of Publication:

  Article

• Publisher:

• Dated:

  1950

• Issue/Volume:

  After 1950

• Other ID:

• Page(s):

  690-695

• Reference List:

  N

• Abstract:

  This improvement in strength-weight ratio has accounted for the rapid growth in the use of prestressed concrete and will be equally potent in pushing along the increased use of lightweight structural concrete. How does this affect the railroad bridge and building engineer? The railroad bridge engineer will realize immediately that the 30 to 35 percent decrease in dead load will not appreciably affect his design since the dead load is usually such a small proportion of the total design load. In the case of prestressed and precast concrete bridges, however, this 30 to 35 percent saving in weight does become important. Many of these structures will be erected under traffic, and the ease and speed with which the members can be handled is important. The lighter the member the quicker and easier it can be seated in its final position. It may also be possible to handle the members with lighter equipment. Remember that a bridge girder made with heavyweight concrete and weighing 30,000 lb will weigh only 20,000 lb using lightweight concrete. Consider also the ease of handling and driving a prestressed concrete pile compared to a heavyweight concrete pile weighing one and one-half times as much. Experience has shown that a prestressed lightweight-concrete pile drives equally as well as a heavyweight concrete pile. Some railroad bridge engineers are considering the possibility of casting prestressed concrete bridges in two pieces rather than the proposed standard three or four pieces per span. Some have already experimented with the assembly of a complete span at an off-the-site location and transporting the completed span to the bridge site. Consider the effect of the saving in weight on either of these two techniques. It is evident therefore that the larger the unit the more important the ratio of strength to weight becomes. In passing, consider other uses of lightweight concrete in the railroad industry in which this saving in weight is important due to ease of handling:(3) Prestressed concrete cross ties.
  (2) Signal foundations and structures.
  (3) Precast cribbing
  (4) Prestressed concrete beams and slabs and precast slabs for freight terminals and other railroad building structures.