US1364621A - Paving mixture and method of making the same - Google Patents

Description

- UNITED STAT-ES PATENT OFFICE;

JosErR R. DRANEY, or RInoEwooD, N W JERSEY, assIeNoR; BY MESNE assren- MENTS, r BITOSLAG PAVING COMPANY, or NEW YORK, N. Y., A CORPORATION 0E DELAWARE.

PAVING MIXTURE D METHOD OF MAKING THE SAME.

1,364,621. Ito Drawing.

To all whom it may concern:

Be it known that I, JOSEPH R. DRANEY, a

' citizen of the -United States, residing at village of Ridgewood, in the county of Bergen and State of New Jersey, have invented new and useful Improvements in Paving Mixtures and Methods of Making the Same, of which the following is a specification.

. This invention relates to 'a pavement mixture as a product, the method of making the same, and also to the final roadway or pavement having its wearing surface constructed from the product.

The invention contemplates, broadly: (1) the method of making an improved paving mixture or product, which method or pro-- cess consists, generally, in mixing with a mineral aggregate preferably of slag, a portion of a suitable filler material, such as pulverized limestone, or other finely divided substance; mixing with a bitumen binding agent, which is preferably blown or oxidized asphalt, the remaining portion of. the filler material; and then admixing these two mixtures to form the final paving material;

(2) a-paving mixture resulting from the r process above described and which is characterized by its homogeneity, density and wearing qualities; and (3) a roadway or pavement which has the ability to withstand the wear of trafiic to which it is subjected. By proceeding in accordance with the method or process herein described, a paving mixture is obtained in which the ingredients or materials are thoroughly and closely amalgamated {the binding agent is properly distributed throughout the mass, so that a homogeneous product is obtained in which the pulverized material "is thoroughly incorporated or impregnated with the bituminous binding agent; and the voids between the particles of mineral aggregate are filled.

to the desired percentage. The resultant paving mixture is impervious to street acids or other moisture and has the attributes of great stability, and the capability of resisting deterioration under'temperature changes or the strain Qftrafiic to which itmay be subjected.

Application filed January 18,1917. Serial No. 143,030.

Specification of Letters Patent. Pate t d J 4 1921 A-roadway or pavement having its wearing surface constructed of the product above described is characterized b its wear-resisting qualities and by its, ability to resist deterioration, crawling, creeping, un'diie deformation, or fracture when .sub'ected to traflic wear, or adverse moistureand heat conditions. It will be'foundthat the wearing surface of the roadwa has great durability, and sufficient rigi ity to stand up under traflic strain, and yet 1t is suflici'ently malleable or resilient to prevent chipping or breaking.

Havingset forth the particular objectsv of my invention, I will now give the materials or ingredients which go to make up which is to take place will occur before the slag is employed in the paving mixture.

Air-cooled blast-furnace-slag is very hard in character, has great tensilestrength, and

The molten I will not chip, crack or break when subjected to ..'ordinary traflic' strains. The surfaces of the particles of slag are very rough, and as they are irregular in shape and slightly porous, or to be more exact, cellular in makeup, the binding material used in the paving mixture may, grip the particles of aggregate and hold them in position.- The physical characteristics of slag are such thata very intimate-binding of-the slag aggregate and the binder will result,- with, of course, less tendency to separation under trafiic and greater stabilityand less likelihood of disintegration under temperature changes, blag fraetureisirregular and rough sothat "close union can be secured betweenithe slag aggregate and the binder, and, furthermore, slag does not exhibit any appreciable ways a very considerable amount of dust,

so that by reason of the smooth and dusty surfaces the stone does not give as satisfactory binding areas as does slag. This is true of the limestone and granite aggregates,

the surfaces of which are smooth, carry a considerable amount of dust and, being nonporous or non-cellular, fail to afford the irregular gripping area found in slag.

Any suitable filler material, such as pulverized limestone or Portland cement, may be employed to fill the spaces or voids between the particles of the mineral aggregate,

. but preferably I use a filler of pulverized slag or slag dust. .Due to the inherent cementitious propertiesof-slag and its porosity cellular structure, the binding agent will adhere closely to the particles of slag-dust, and shifting of the fine particles of filler is guarded against. .As the bituminous binding agent, I employ blown or oxidized asphalt which may be produced very economically from heavy asphaltic base petroleums. It is found that blown or oxidized asphalt is less malleable than asphalt whi-h is prodnced by other methods,-but whi e its cementitious'qualities are not as great as the usual distilled asphalt, yet it is characteri element of rigidity is such that. it maintains ized by its low susceptibility to moisture and temperature changes. Due to its rigidity, blown asphalt is particularly adapted for usein asphalt pavements for it has the necessary tensile strength to standup under traffic strains without danger of disintegrating, and vyet it possesses the necessary malleability or resiliency to resist cracking or. chipping and, additionally, its

the particles ofmineral aggregate and filler material against shiftin the high cementitious qualityof distilled asphalt, for it becomes, by reason of oxidation, somewhat waxy-incha'racter and its facesfo stone aggregates and for that reason ,has by some been heretofore regarded as of little value in paving mixtures; 1 I

Combined, howefver yvith slag, the a cities of which have'been heretofore pointed out, it producesastrongly. adherent mixture, fornotwithstanding its relatively low cemerititious properties it ri s and adherestenaciously to the rough cc ular slag frac- 66 cause of. its cellular formation, is not particularly well adapted for use with the ordinary asphalt cement, the reason for this being that the continuous absorption of oil from the ordinary asphalt by the porous or cellular slag'soon results in a deadening of the asphalt due to loss of oil and the disintegration of the asphalt binder.

The blown asphalt exhibits but little change under varying temperatures, and is, for that reason, more stable, and a pavement formed of a mixture in which blown asphalt or cement is used has greater and more uniform rigidity under all conditions, although it is resilient and malleable enough to be proof against chipping or fracture even under conditions of low temperature.

In carrying out my improved process or method, I first select hard, air-cooled, blast furnace slag, preferably weathered, as hereinbefore .stated, and crush the same into 1 small particles, so that the particles will pass through a screen of about one-fourth inch mesh: After careful screening, the slag mineral aggregate is graded into sizes so that, when mixed, the voids or-spaces between the larger particles may be filled by the particles of the next smaller size, and the voids or spaces between-the second size of particles are filled by the particles of the still smaller size, and so on down through the various gradations. The graded mineral aggregate is dried and heated preferably to a temperature between 350 and 4 and while hot itis-measured into a suitable mixing apparatus.

1 next divide the filler material into two portions, one of the portions being, in wei ht, approximately equal to thirty-five (35% per cent. of the weight of the binding agent which is to be used in the mixture. The other portion of the filler or pulverized material is added to they graded and heated slag, the filler being added in a cold condition. The mineralaggregate and the added Y. pulverized material are then mechanically Blown asphalt, as stated above, has-not" mixed 'u-ntil uniform and the filler is properly distributed throughout the mass of the slag aggregate. Y The asphalt composed iof blown or oxidized heavy petroleumbases is then melted in a kettle and, while it is-in molten condition, there is added thereto the remaining 'portion of filler dust or fines, and, preferably, this portion of fines is equal to about 35% of the'weight of the bituminous binding agent. The asphalt is maintained in molten condition and. is thoroughly agitated by any suitable means, so as to thoroughly and uniformly distribute the fines th-roughoutthe mass of asphalt, and to keep the fines in suspension.

By mixing a} portion of fines, in substantially the amount, specified, with the blown-asphaltaa primed mixture is secured,

- the asphalt and fines, so that a very ready blending or mixing with the remaining filler and slag is secured.

. Furthermore, this preliminary introduction of the fines into the blown asphalt takes up to a considerable extent thefree oil and gives a mixture which isproperly tempered for mixing with the remainder of the filler material and the aggregate.

' The next step of my process consists in adding the fines-impregnated asphalt, in

a molten condition, to the heated mixture of slag and filler material, which has been previously measured into the mixer. The

resultant mixture is then thbroughly agitated, so that the fines impregnated asphalt is thoroughly distributed throughout the mass. Upon continued stirring the sur-' faces of the particles of the mineral aggregate are properly coated with the asphalt, and the fines are thoroughlyv impregnated with the bitumen, so that a homogeneous and uniform paving'mixture is obtained.

The paving material resulting from the process above described is capable of taking care of a' wide range of traffic conditions,

and may be laid on any suitable foundation, such as a concrete base, old macadam, old

brick pavements, or a layer of slag. After.

mixin the mineral a re ate fines and g C 9 7 binding agent in the manner above degeous over the use of distilled asphalt, in

scribed, the resultant paving mixture is placed in air tight vehicles and transported to the location of the work. On arriving at the site, the mineral aggregate is dumped at a point sufficiently remote from its place of final deposition to allow all portions of v the load being rehandled by the shovelers before final placing. It should be spread to a uniform depth upon the foundation previously prepared) and suitably rolledso that it will surface.

I have foundthat: by proceeding in accordance with the method above described, a final paving mixture results, in which the bituminous binding agent composed of provide a compressed wearing blown asphalt isthoroughly distributed" throughout the .mass. "The particles of mineral aggregatesare properly coated and the asphalt is so thoroughly incorporated with the pulverized material, that the 'interstices or pores of the pulverized material are filled "and an intimate and close association of the mineral aggregate and filler with the.

as halt is obtained.

am aware that it is broadly old to use slag in paving mixtures, but it is to be noted that, in the present instanoe, the .slag. is-

employed in connection with blown or oxidized asphalt. pointed out, blown asphalt has, 'not 'the same cementitious properties as ordinary distilled asphalt, but its use is advanta As has previously beenproperties, so that after the pavement is laid a chemical change takes place in the slag, and a close chemical union is obtained between the-slag and the blown asphalt.

Furthermore, as the slag particles are irregular in shape and are/characterized by their porosity or cellular structure, the asphalt when mixed with the slag will tend to flow into the pores, and thus hair-like fingers are formed which grip the aggregate and hold it fast. As the own asphalt is characterized by its rigidity, and the mineral aggregate of slag by its inherent cementitious properties, irregular shape and porosity or cellular formation, there'is present-a very close bond or union between the particles of the aggregate and the blown asphalt. The blown asphalt tenaciously grips the particles of slag. so that a very tough product is obtained. The mixture is very homogeneous and dense, and it IS only slightly susceptible to temperature changes and is characterized by its ability to resist street acids or other moisture.

A roadwayformed with a wearing surface composed of-my improved product is very durable, economical and non-slippery, and pleasing to the eye. It possesses low susceptibility to temperature changes, great toughness, and suflicienti/rigidity to prevent creeping or deformation, and yet it is su'fliciently elastic or resilient to prevent.

craokin or chippin What I claim is 1. The process of producing asphalticf paving material, which consists in mixing a portion of the filler material with a mineral aggregate of slag, mixing the remaining portion of the filler material with the bituminous binding agent, and then admixing" the two mixtures thus formed.

2. The process of producing asphaltic paving material,.which consists in mixing a portion of thevfi ller material with a mineral aggregate of slag, mixing the remaining portion of the filler vmaterial with a bituminous binding agent of blown or oxidized asphalt, and then mixing the two mixtures thus formed.

3. The process of producing asphaltic paving materlal, which consists in crushing the mineral aggregate composed of aircooled blast furnace slag, grading theslag, heating the slag, mixing with theheated and graded slag a portion of the pul,verizedfiller material, heatingthe .as phaltic binding agent to a molten-mass, adding the remaining portion ofthe filler material to the the fines, and then admixing the two mixmelted binding agent, and then admixing and thoroughly agitating the mixtures thus formed.

4. The process of producing .asphaltic paving material, which consists in melting the bituminous binding agent, adding to the molten binding agent a portion of the fines equal to approximately 35% of the weight of the binding agent, mixlng with a mineral aggregate of slag the remaining portion of of the asphalt, mixing with a mineral aggregate of slag the remaining portion of the fines, and then admixing the two mixtures thus formed.

6. An asphaltic paving material consisting of a mineral aggregate of slag, a suitable filler material, and a binding agent composed of blown or oxidized asphalt.

7. An asphalt-i0 paving material consisting of a mineral aggregate of air-cooled blast-furnace slag, a pulverized material, and a binding agent composed'of blown or oxidized asphalt.

8. An asphaltic-paving material consisting of a mineral aggregate of air-cooled blast-furnace slag, a filler nraterial composed of pulverized or dust-like slag, and a binding agent of blown or oxidized asphalt.

9. A roadway comprising a suitable 'foundation and a layer thereon formed of a mineral aggregate of slag, a filler of pulverized material, and a binding'agent of blown or oxidized asphalt.

In testimony whereof I have hereunto set my hand.

' JOSEPH R. DRANEY.