The L&NE used boxcars for cement service. Originally they were boxcar red and changed to the black with white sill stripe scheme about 1957 or so. The covered hoppers were used for bulk cement service and the boxcars usually hauled it in bags like you get at Home Depot, etc. I'm not sure if they were ever used for bulk loading like you would use a boxcar in grain service though. More research is necessary!
TomPM is correct in saying the CNJ purchased the remnants of the L&NE that were in their cement area and continued to operate it.
There were several series of boxcars over the years including PS-1 and a car similar to the PRR X-29. Email me offline and I can fix you up with cars numbers.
Roger Huber