US2268810A - Asphalt composition - Google Patents

Description

Patented Jan. 6, 1942 ASPHALT COMPOSITION Folkert Dijkstra, Amsterdam, Netherlands, assigner to Shell Development Company, San Francisco, Calif., a corporation of Delaware,

No Drawing. Application March 2, 1940, Serial No. 322,012. In the Netherlands April 5, 19 39 6 Claims.

This invention relates to a process for manufacturing compositions particularly suitable for road construction purposes, which compositions consist of sand, clay, with or without the addition of stone chippings, water and bitumens, can be worked cold and after compression yield the desired final products. This compression may take place after spreading on the ground, such with a view to making floors, roads, flying fields and the like, while the mixtures can also be compressed to blocks, slabs and the like.

In particular, however, the process concerns an improvement of the ground stabilization process (so-called soil stabilization).

It is known that from mixtures of sand and clay, with or without the addition of stone chippings and water, compositions can be produced having favorable mechanical properties, greatly dependent on the water content, which in general may vary only between certain limits. dependent on the composition and the gradation of the material.

Further it is known that a change in the water content can be restricted by the addition of bitumens, for instance bitumens originating from mineral oils or mineral oil products.

It has been found that not all bitumens originating from mineral oils or mineral oilproducts have an equally good effect in this respect.

It has now been discovered that solid paraffin wax exerts a beneficial effect on asphalts which are used for soil stabilization and the like. This is contrary to what was previously believed in that paraflin wax has been regarded as harmful in asphalt used for road building and similar purposes. The present invention consistsof adding solid parafiin wax to asphalt which is deficient in natural occurring wax. The amount of added wax should be such that the finished asphalt contains at least 2% wax calculated by the Holde method. Preferably the wax content should not be over 10% since amounts in excess,

of about 10% adversely affect the ductility of the asphalt.

The wax should be melted before it is mixed with the bitumen and if a normally solid bitumen is used it too should be melted. Any form of mixing may be used.

The asphaltic residues should preferably have viscosities exceeding about 300 degrees Engler at 50 C. They may originate from straight-run distillates as well as from hydrogenation or cracking processes. Very favorable results are obtained with the use of cracked residues.

The residues may be applied as such, diluted with solvents,'such as gasoline, or in the form of aqueous emulsions.

The following experiments indicate the effect obtained with the process according to the invention: v

A'mixture of parts by weight sand, 30 parts by weight river clay and 10 parts by weight water was compressed to a cylinder 10 cm. high and havinga diameter of 5 cm. The cylinder was kept for a week in a space with a degree of dampness of 100%. placed on a sand bed saturated with water in a space in which the degree of dampness also was 100%.

After 1 hour the cylinder was found to have absorbed 24 g. water; after 24 hours it had broken up. I

A cylinder made and treated in the same way, except for the addition of 2.6 parts by weight of an asphaltic fuel oil (viscosity at 50 C.=300

degrees Engler), was found after 24 hours to have absorbed 22 g. water and after 10 days it broke up.

1. In the process of soil stabilization, the improvement comprising adding to an asphalt an amount of solid parafiin wax suflicient to materially increase itswater repellency and to give it a wax content of from 2% to 10%, and combining the resulting product with water and an aggregate containing clay.

2. In the process of soil stabilization, the improvement comprising adding to an asphalt defi cient in paraffin .wax an amount of solid paraffin wax sumcient to materially increase its water repellency and to give it a wax content of from 2% to 10%, and combining the resulting product with water and an aggregatecontaining clay.

. 3. The process of. claim 1 wherein the aggregate contains stone chippings and sand.

4. The process of claim 1 wherein the asphalt is a cracked residue.

5. The process of claim 1 wherein the amount of paraflin wax is insulficient to adversely affect the ductility of the asphalt.

6. The process of claim 2 in which the asphalt is a cracked residue.

FOLKERT DIJKSTRA.

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