Rock asphalt

Tar Sands. Tar sands (qv) are considered to be sedimentary rocks having natural porosity where the pore volume is occupied by viscous, petroleum-like hydrocarbons. The terms oil sands, rock asphalts, asphaltic sandstones, and malthas or malthites have all been appHed to the same resource. The hydrocarbon component of tar sands is properly termed bitumen. 

Table 1. Typical Composition and Properties of Rock Asphalts...

The binder was applied by a distributor truck at a rate of 0 4 gal / yd (1 81 1/nrv Three hundred feet (91 4 meters) of 5/8 inch (15.87 mm) precoated rock asphalt were dropped on the binder followed by 2700 feet (823 meters) of 3/8 inch (9 5 mm) sandstone ... 

I here is much evidence (1) that naturally occurring asphalts were valued for their cementitiousness, inertness, and waterproofing qualities as early as 3800 B.C. But it is only since they became readily available from petroleum sources that asphalts have been widely used on a large scale. The first modern asphalt pavements were constructed about 1852 near Paris, France, of a rock asphalt mastic (8). From 1870 to 1876 several pavements, using rock asphalts and Trinidad lake asphalt were laid in eastern cities of the United States (5). The demand for such pavements was relatively small and was filled by natural asphalts imported from Trinidad and Bermudez lakes during the next 35 years. 

By 1911 the tonnage of domestic petroleum asphalts exceeded the importations of Trinidad and Bermudez asphalts. Starting about 1920, and coincident with the rapid expansion in rural road building, the production of petroleum asphalt has rapidly increased, as shown by Figure 1, so that it exceeded 9,000,000 tons in 1949. The ratio of petroleum to native and rock asphalt production in 1949 was approximately 8 to 1 (186). 

Rock asphalt bitumen that occurs in formations that have a limiting ratio of bitumen-to-rock matrix. 

All other sources in Table VIII are from Zagros locations, especially the foothills and valleys from Ain Gir to Bebehan from which multiple samples were obtained. The seepages of Ain Gir contained more bitumen and less sand than the dried and rock asphalts, which are much alike. Weathered and unweathered rock asphalts from Mordeh Pel were hardly distinguishable, as were the Bebehan samples in other respects than bitumen content. The samples from M-i-S, Mordeh Pel, and Rijab are probably too lean to have been used as source materials. But the similarities at Ain Gir and Mordeh Pel suggest that the bitumen in any seepages at other sites would have resembled that in the asphalts there. 

The term bitumen (also, on occasion, referred to as native asphalt and extra heavy oil) includes a wide variety of reddish-brown to black materials of semisoUd, viscous to brittle character that can exist in nature with no mineral impurity or with mineral matter contents that exceed 50% by weight. Bitumen is frequently found filling pores and crevices of sandstone, limestone, or argillaceous sediments, in which case the organic and associated mineral matrix is known as rock asphalt. 

Site Conditions. The indigenous soil at NCBC is sand to sandy loam, intermixed with some clay. The HO storage site was stabilized with Portland cement approximately 30 years ago. Since that time, additional fill materials, including shell, rock, asphalt, and tar, were... 

Senonian age Ghareb Formation, bituminous rocks, asphalts and oil shows Dead Sea Area Israel... 

Rock asphalt is natural asphalt found in solid form. It was formed millions of years ago when layers of petroleum harden after heavier components settled while lighter components evaporated. The hardening took place, in most of the cases, within the pores of rocks (mainly limestone or sandstones) thus, a number of mineral materials are normally found within rock asphalt. 

Rock asphalt, as natural asphalt in liquid-viscous form, was used historically in engineering works but today its use in road works is rare. Rock asphalt nowadays is used only as an additive to petroleum bitumen. Since it is a very hard material, its use is to harden petroleum bitumen. 

The largest natural surface deposits of rock asphalt that are commercially exploited are found in Utah in the United States (28 km ) and Kermanshah in Iran. 

The rock asphalt in the Uintah Basin in Utah has the trade name gilsonite, from S.H. Gilson, the founder of a mining company in 1888. 

The only exception seems to be the rock asphalt of Buton Island (south of Sulawesi Island) in Indonesia. In this island, the rock asphalt forms hills and mountains. This porous rock contains hard natural asphalt (penetration of 5-10 dmm) at 15%-30% and soft limestone with fossilised shell impurities. The extraction is very simple and cheap, because of low local labour cost thus, it is used locally for the production of bituminous mixtures. 

Natural rock asphalt in larger deposits can be found in the Jordan Valley, Dead Sea banks, France, Switzerland, Antilles, Venezuela and Cuba. 

Natural asphalts Trinidad lake asphalt, rock asphalt,gilsonite (2), (4), (6), [8], [9]... 

Natural asphalts such as Trinidad asphalt, rock asphalt or gilsonite are blended with bitumen derived from crude petroleum in order to improve its properties. Since the above additives have very low penetration and very high softening point, the resulting bitumen becomes harder. Since the chemical composition of the natural asphalt is similar to the bitumen from crude petroleum, performing the blending procedure is far easier and homogeneity of the final modified bitumen is ensured. 

The residue from distillation is a black, tarry material called petroleum asphalt. It is used in making roads, for asphalt composition roofing materials, for stabilizing loose soil, and as a binder for coal dust in the manufacture of briquets for use as a fuel. A similar material, hitumen or rock asphalt, is found in Trinidad, Texas, Oklahoma, and other parts of the world, where it presumably has been formed as the residue from the slow distillation of pools of oil. 

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