Citation

AREA Bull. 1958; 59: 762-795.

Copyright

(Copyright © 1958, American Railway Engineering Association)

DOI

unavailable

PMID

unavailable

Abstract

Specimens of southern yellow pine and Douglas fir were treated with creosote, a 60:40 mixture of creosote with coal tar, and a 50:50 mixture of creosote and petroleum in the continuing investigation of methods of fireproofing wood bridges and trestles. Laboratory burning and temperature measuring apparatus were described. Weight losses after burning, internal temperatures during burning, evaporation rates of the paints, ratio of burned oil to burned wood, toxicity studies of residual preservatives, and performance specifications were studied. Under standard fire testing conditions creosote-treated specimens loose more weight than creosote-tar or creosote-petroleum treated specimens at retentions of 30 and 20 lbs per cubic foot. Creosote-tar treated timber looses more weight than creosote-petroleum treated timber. At low retentions no significant difference is apparent. Protective coating integrity is a function of the insulation it confers to the surface so that internal temperatures do not reach the boiling range of the preservative oils. The same protective coating confers different degrees of protection placed on aged timber as opposed to freshly treated timber. Aging of timber or evaporation of low-boiling constituents in preservatives influence protective coating adhesion. Timbers with high preservative retentions require more time to reach the same conditions as adjacent timbers in structure with lower preservative retention.