Air drying characteristics of garjan Dipterocarpus spp. railway sleepers were
investigated employing 1 x 5, 2 x 5, 1 x 7 and 2×7 piling methods. Although there
was no significant difference among the drying periods in different methods, the
2×7 method appeared to be the most efficient one. This method exhibited a
relatively shorter drying time irrespective of higher density and higher initial moisture
content of sleepers as compared to those in other methods. The faster drying
in the 2×7 method was attributed to better air circulation. Sleepers stacked in the
month of April, dried down to 28% mosisture content in about eight months on
the average. It is recommended that garjan sleepers be air dried following the
2×7 method during the active drying season beginning November, instead of April,
as was done in the present study, with a view to achieving further reduction in
total drying time.
The moisture distribution inside the sleepers was highly variable ; the moisture
gradient was steeper with increasing depth of the zone, but the steepness of
the gradient decreased with increasing drying time.