US1815089A - Process of manufacturing plastic asphaltic compositions for pavements - Google Patents

Description

Patented July 21, 1931 UNITED STATES PATENT OFFICE FREDERICK C. ALSDORF, OF CHICAGO, ILLINOIS PROCESS OF MANUFACTURING PLASTIC ASPHALTIC COMPOSITIONS FOR PAVEMENTS No Drawing.

This invention relates to an improvement 1n the method of mlxmg certam asphaltic compos1t1ons that are now in commercial use in the layin of roads,

streets, walks, 7 driveways, etc. whereby the mixed asphaltic road material maybe more easily unloaded from railroad cars, shoveled out of piles, spread upon roadways.

and

This invention is limited to those asphaltic p compositions which are mixed at'a temperature less than the boiling point of water. Such compositions contain a mineral aggregate, a fluxed asphalt and a liquefier.

liquefier is defined as a liquid hydrocarbon which will volatilize on exposure to air, within a period of two years ina roadway.

The

' liquefier maybe added to the asphalt before it is mixed with the aggregate or the liquefier may be added to the aggregate before heated asphalt is added or the liquefier may be added to a mixture of aggregate and hot asphalt. The above processes are now in use and my invention is confined solely to an im' provement in the method of mixingthe constituents in the above processes.-

Such compositions depend onthe evaporation of their volatile constituents for their setting uppower.

The control of this hardin cool weather.

On the other hand such a comparatively high percentage of liquefier in the asphalt makes it impossible to keep enough asphalt on the separate particles of aggregate to insure a lon severe tra c .and weather conditions.

life to the composition under The Application filed October 1 5, 1928. Serial No. 312,738.

thinned asphalt may run through truck loads of mixed material orthrough the bottom of loaded railroad cars, thus decreasing the percentage of the original mixtures. The setting up process is delayed and the composition may be so thin that it will spread out under a roller and trafiic.

Vi-ch my improved method it ispossible to use the minimum quantity of liqu'efier required to flux the asphalt or to coat the stone previous to or subsequent'to the addition of hot asphalt, at the same time any amount of asphalt can be added to the aggregate, depending on its grading, as to insure a proper degree'of thickness of coating. v My improved method of handling is at tained by adding a smallamount of Water with an emulsifying agent assoap, clay, and the like to'the mixture, while it is being made.

A hydrocarbon emulsion can also be used.

The effect is to produce a slight emulsification of the asphalt on the surface of each separate particle. This emulsification is not sufiicient to prevent the packing action of a roller or traflic upon the mixed material when spread on a roadway. Only enough emulsi-' fying agent is added to emulsify but a small part of the asphalt in the mixed material.

The general effect, until the water has evaporated, is to reduce the ductility and tenaciousness' of the asphaltbinder permitting the mixed material to be handled and spread much more easily than if no partial emulsification has been produced. After the water has evaporated, the original ductility and tenacity are restored to the asphalt binder.

In cool weather the effect of the slight emulsification in the mixture is more pron unced. At temperatures of 50 degrees Fahrenheit it is impossible with some standard mixtures to unload railroad cars filled with asphaltic material, not emulsified in any way, without resorting to heating the set up, mixed material by steam, while with identically the same material partially emulsified o g V the unloading 7 heating.

- emulsion.

is accomplished easier with no On account of the packing action of a pile of mixed asphaltic composition I have found that water is retained in the pile for some time and that the emulsified efiect is retained until the water has entirely dried out.

Without limiting myself to these proportions or the material employed I have found the following mixtures tongive good results:

1. An improved method of producing asphaltic compositions which comprises add ing to a cold mix asphalt composition oomprising aggregate coated with asphalt fluxed with a liquefier normally used in the art, ajsmall amount of Water and an emulsifying agent to produce a partial emulsification only of the asphalt largely on the surfaces of the asphalt coated particles of mineral matter.

2. An improved method of producing asphaltic compositions which comprises adding to a cold mix asphalt composition comprising aggregate coated with asphalt fluxed with a .liquefier normally used in the art, a small amount of a hydrocarbon FREDERICK o. ALSDORF.