Railroads have long been a hauler of cement, especially in large bulk quantities. Cement, like many commodities, was once commonly hauled in boxcars. The dry cement was either loaded by hand in heavy sacks, or poured in bulk through hatches in the roof. Unloading was done manually by opening the doors and going inside the dusty car with shovels. In some parts of the world, it is still done this way. Imagine that job on a hot and humid day!
In theory, use of boxcars for the service meant that the cars could also be used for other commodities. Even after a thorough cleaning however, there were many loads to which these dust boxes simply couldn’t be assigned. Consequently many ended up dedicated to this service and can often be identified even in poor-quality black and white photos from the heavy streaking down the car sides which often left all of the reporting marks, numbers and other data obliterated by caked-on cement dust.
Beginning in the 1930s, some railroads began taking the next step and began building covered hoppers. Cement was one of the first commodities chosen for these new cars. Now unloading could be accomplished much more efficiently through the hopper doors on the bottom of the car. Note that on most covered hoppers, the unloading doors are parallel to the ground, not angled like on traditional open-top cars. Despite the added efficiencies, the cars were not an overnight success. It would take some time for industries which received the cars to modify their facilities for bottom-dumping cars instead of trackside platforms.
Due to the density of cement, the covered hoppers which carry it tend to be rather short. Two-bay cars like the Pullman Standard PS-2 2003 are the most common. Some smaller three-bay cars can be found in this service as well. This practice holds true to the present day. Cement can still be found regularly in freight trains. Like the boxcars that preceded them, the covered hoppers in this service often show grey streaking down their sides and caked-on cement near the roof-line. If you enjoy weathering your freight cars, these effects are easy to recreate with chalks and even a little plaster.
With their short length and often dramatic weathering, cement cars are a natural choice for modelers whose layouts feature tight curves and small sidings. Even a short string of these cars can add a lot of interest to a consist!