Abstract: A process of producing an asphalt-impregnated fiberboard comprises the steps of forming an aqueous slurry of a fibrous material and asphalt, the solids content of the slurry being less than about 8 weight percent, mixing the slurry to uniformly distribute its components, dewatering the slurry to form a wet mat, pressing the wet mat to consolidate it, and drying the consolidated wet mat. Fiberboards made by the process can be employed as durable resilient expansion joints between various types of structural members.

Abstract: A method for texturing the surface of an acoustical fiberboard by utilizing a wheel blast machine. The fiberboard is conveyed through a housing wherein at least one first centrifugal blasting wheel throws abrasive particles at a portion of the fiberboard surface to abrade it. A blower provided in the housing removes spent abrasive particles thrown by the first wheel(s), and then at least one second centrifugal blasting wheel in the housing throws abrasive particles at the remaining untreated surface to complete the abrasion, whereby removal of the spent particles by the blower prevents masking of the surface and allows the formation of a pleasing and uniform pattern over the entire fiberboard surface.

Abstract: A method of producing an acoustical mineral fiberboard comprising(a) forming an aqueous slurry of mineral fiber-containing solids suitable for forming an acoustical board, the solids content of the slurry being sufficiently high to bring about predominant formation of nodules of mineral fiber throughout the slurry upon mixing of the slurry;(b) mixing the slurry to form the nodules of mineral fibers;(c) dewatering the slurry to form a wet felt;(d) drying the wet felt; and(e) texturing one surface of the dried felt without mechanically punching holes in the surface.