US1405302A

US1405302A - Paving block and process of making the

Info

Publication number: US1405302A
Authority: US
Publication date: 1922-01-31
Anticipated expiration: 1939-01-31

Description

UNITED STATES JAMES S. DOWNARD, OF ARDMORE, OKLAHOMA.

PAVING Bnocx .AND rnoonss or mum rnn snnn.

No Drawing.

To all whom it may concern:

Be it known that I, J AMns'S. DOWNARD, a citizen of the-United- States, and a resident of Ardmore, in the county of Carter and State of Oklahoma, have invented certain new and useful Improvements in Paving Blocks and Processes of Making the Same, of which the following is a specification.

My invention relates to paving blocks and the process of making the same, and particularly to a block used as a wearing surface upon a suitable base or as a pavement without a base other than the block or sheet itself Which is manufactured from natural asphalt rock or combinations of other mineral aggregates in combination with asphalt rock,

It has been hitherto proposed to form asphalt paving blocks from a mixture of particles of stone compounded with sand and asphalt'as mined is broken into pieces of provide a mixed with asphaltum after heating, the asphaltum cementing the particles together and coating them, which recess is carried on under high pressure. This process is defective in that, while 10% to 11% is the eflicient percentage of bitumen in a paving mixture, it produces a mixture which rarely exceeds 5% for the reason that if it is rich in bitumen, the blocks lose their original form when subjected to the heat'of the suns rays, and cannot be stored because they. crack, break down or lose form. Manufacturers have endeavored'to avoid these difficulties by reducing the amount of cementing asphalt and by making the blocks, under great pressure, but it is obvious that the resulting material is too brittle becauseflof deficient bitumen.

It is a purpose of my invention to overcome those difficulties and to produce blocks which can be stored, shipped and used without losing their form or integrity under ordinary climatic conditions by providing a process of forming blocks which permits the use of 10% or more of bitumen in each block.

It is also a. purpose of my invention to rocess of'making blocks which allows bloc s to be manufactured under ordinary pressure' by simply molding the material and to contain any percentage of asphalt desired. I I

In carrying out my invention, natural rock predetermin sizes depending upon the thickness gs; e ultimate block and the parclimatic conditions.

Specification of Letters Patent. Patented Jan. 31, 1922. Application filed September 30, 1919. I Serial No. 527,432.

ticular use to which it is :to be adapted. These particles of asphalt are carefully selected so that they will fit closely together and thus reduce the voids in the mineral ag regate to the least possible amount.

mastic is' now prepared byfenriching rock asphalt powder with pure bitumen (asphalt) until it is plastic or mastic. The pure itumen must be of a high melting point so that the temper of the mastic is not affected by exposure to the sun when the surrounding air shows a temperature of Fahrenheit. To secure such a mixture there is added to the mastic any asphalt or.asphaltite that will raise the melting point such as gilsonite, imponsite, grahamite, mineral rubber, or blown asphalt.

voids between the particles of natural asphalt rock as assembled, the entire mass be ing thoroughl mixed in a suitable mixture" and finally de ivered=,to the moulds where it is moulded into blocks of the desired size. The finished blocks are subsequently cooled with water, after. which they are stacked in storage for future use.

The resulting block or sheet, depending upon the particular use of the material, is substantially a natural rock asphalt pave ment composed of particles of natural ashalt arranged to reduce the voids and oined together with a mastic to form a homogeneous mass which rovides for expansion and contractiomehminates the possibility of cracks, and insures the block retaining its original form under ordinary It is necessary that the natural rock as halt constitute a major portion of each bloc or sheet, in other words, each block or sheet must contain 51% or more of the rock'asphalt so that it essentially consists of asphalt in its natural state.

Although I have herein described only one understood that various changes may be made in the various ingredients and steps in the process without departing from the spirit of the invention- .and the spirit and scripe of the appended claims. a

claim! 1. A process of mak ng. pavingblocks which consists in disintegrating natural asaving thus describedmyf invention, 1"

' phalt rock into; fragments, arranging the particles to mduce the maids t0 the p05- sible amoun.t,'mixiz1g the same with a mag- :i-c, and finaflymoidingtha mass into blacks, 2. A pmcess of making paving; blmkis which consists in arrangizag fine fI'gQIQEIfiS 0f natural as me vcids its the least 3; @sibie Bumbag :c r bssquen J @ssling 531% block A "paving 1010-211: comprising particles 0:? a1 asphalt reek anangefl r-Bduce JJ-hE u be: 0; voi to a mini