USRE7997E - Improvement in concrete pavements - Google Patents

Description

5T0 all whom it may concern HBONNET" BONNET, of the city and county of San Francisco, in the Stateof California, have fy-invented certain new and useful Improvements in Concrete Pavements; and that the follow- .'--ing specification is a true, clear, and complete '-'=description thereof.

Said invention consists, partially, in a pavstances combined with mineral tar and with posed-of concrete embodying earthy bitumirock is hot, and molded under heavy pressure.

. greater proportion of earthy .rnatter than the employed for properly tempering the asphalt.

' and mineral tar.

err-Ann is in. Wi-Irrm, TRUSTEE.

Iran STATES Pirrnn'r OFF-ICE.

' .eonnii'r "SKINNER m) onner BONNET,'OF SAN FRANCISCO, CALIFORNIA,

nssicnons nr MESNE ASSIGNMENTS, T0 JAMES n.

:M PRO-VEM ENT, m CONCRETE AVEM EKIINTS.

Specification forming part of Letters Patent No. 105,502, dated uly 19, 1 870; Reissue No.. 7,99 7", dated 'Decembcr 18, 1877 applicationfiledNovember 26, 1877.

Be it 'known that we, ROBERT SKINNER- and.

lug-concrete embodying earthy bitlllllillOllS subcalcarcous rock while the latter is thoroughly heated;- and, further, in paving-blocks comnous substances combined with mineral tar and heated calcareous rock, mixed while the The asphalt of California, employed in developing this invention, contains a much usual asphalts of conunerce. The asphalt is heated sufiiciently to work it down into a granular mass, and to discharge therefrom the gases and watery vapors. The mineral tar is "The previous state of the art. in concrete pavements embraces concretes of asphalt or coal tar, interchangeably employed, andbroken limestone, boiled together and laid in mass, and also formed into flags and blocks, by pouring the same into molds and allowing itto cool, after the manner of casting.

Ooncretcs of coal-tar, pine-tar, sand, gravel, and broken stone mixed, and molded into locks under pressure, are also well known. In the preparation of these previous concretes it has been'customa-ry to employ fire-heat for drying the broken rock, sand, and earthy matter, and, although this drying process is essential, it is not enough in accordance with this invention that the calcareous rock be 'well dried; but it fuust be well heated prior to and at the time of compounding it with the asphalt While thus well heated the rocky particles, coarse and fine, are more or less expanded, and the air is largely driven therefrom, so that when in that condition they are mixed with the asphalt and mineral tar, I

attained. I

It'is, therefore, to be distinctly understood- Drvrsiou B.

each particle becomes a prompt absorbentof I the bitumen, and as the mass cools a'practi stone-is cally-perfect union of the asphalt and that the concrete subject of these Letters Pat,

cut is limited not only to a composition con Under no circumstances can the calcareous rock, however dry, be mixed while cold with the. hot asphalt, and good results secured, either as regards absorption by the rockyp'articles or satisfactory working in molds, be cause the degree of heat requisite for properly treating the rock would be positively injurious to the asphalt. Moreover, the-heat contained in the granulated rock secures good r.:-..-;ults while molding the blocks under heavy pressure in hydraulic or, other presses.

Great care should be taken not to burn the limestone in heating it, because quicklime in asphalt-concretes. is, for many reasons, positively objectionable.

The calcareous rockis crushed and granulated, preferably, so that all of it will pass through a q'uarter-inch-mesh screen, and such crushing insures a proper proportion'of dust and fine particles. I

The mixing of the vconcrete is efl'ected by means of heated revolving cylinders, preferably provided with interior horizontal rods, or other appliances for tumbling the mass;

The blocks are best molded under the origi nal heat of the concrete; but it can be done with reheating.

, Eight hundred pounds of California asphalt, twenty gallons of mineral tar, and three hundred pounds of granulated and powdered ca1- careous rock, compounded with three hundred poundsof slag and three hundred-pounds of coke, granulated andheated in like manner as the limestone, constitutes a concrete suitable for molding under pressure for the manufac- NUTTMAN, AND

indurntio rooms roek.- v

What is claimed as new; and to be secured by .these Letters Patent, ie-

.1. Paving-concrete containing asphalt, mineral tar, and. granulated calcareous mck, pre viously heated, and; mixed. with the asphalt W113; dthe rock 'is hot, substantially as 1esen 11 may be produced by increasing or 4 reducing the pro'portionof granulatede teining asphalt, mineral tar, an

calcareous rock, mixeg1- after the rock has been L I well heated and-while hot, substantially as dei ROBERT SKINNER- 2. Compressed 'eonerete pevin Mocks congranulated scribed.

' B. BONNET. Witnesses:

S. M. Tamar,

n. H. Tmuun