Trinidad asphalt

The asphalt that comes from Trinidad Island is the most widely known natural asphalt, in semi-solid or very viscous form, which is currently used in highway engineering constructions. Deposits are superficial and form lakes , which is the reason that this natural asphalt is also known as Pitch lake or Lake asphalt . The largest lake asphalt can be found in the south part of Trinidad Island, near La Brea. The total surface of the lake is approximately 500,000 m (50 ha), with a maximum depth of approximately 90 m, and it is estimated that there are approximately 15 million tonnes of asphalt. This constitutes one of the largest deposits of very good quality natural asphalt in the world (Chilingarian and Yen 1978). 

The paradox is that although the asphalt is mined, the deposits remain almost the same. Surface mining is possible since the lake asphalt surface is hard enough to withstand the loads of the mining machinery. 

Trinidad natural asphalt contains a small amount of water and foreign materials, mainly topsoil and stones, which are removed once the asphalt is heated, at 160°C, and sieved . The final product, known as Trinidad Lake Asphalt (TLA) or Epure, has the following typical composition 54% asphalt, 36% mineral matter and 10% organic matter. Its specific gravity varies from 1.39 to 1.44 g/cm. The TLA s typical chemical composition, together with the typical chemical composition of other natural asphalts, is given in Table 3.1. 

The pure asphalt (Trinidad Epure) is very hard (penetration, 0-2 dmm softening point, 93°C-99 C) to be used alone in the production of bituminous mixtures. Hence, it is mixed with soft crude petroleum bitumen (usually 200 pen [dmm]) in order to produce suitable paving asphalt (a proportion of approximately 50/50 results in a 50-pen asphalt/bitumen). 

Place/country of appearance bitumen content (%) Saturated hydrocarbons (%) Aromatic hydrocarbons (%) Resins (%) Asphaltenes (%) Sulfur content (%) 

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Trinidad asphalt has a relatively uniform composition of 29% water and gas, 39% bitumen soluble in carbon disulfide, 27% mineral matter on ignition, and 5% bitumen that remains adsorbed on the mineral matter. Refining is essentially a process of dehydration by heating the cmde asphalt to ca 165°C. The refined product averages 36% mineral ash with a penetration at 25°C of about 2 (0.2 mm), a softening point (ring and ball method) of 99°C, a flash point (Cleveland open cup) of 254°C, a sulfur content of 3.3%, and a saponification value of 45 mg KOH/g. The mineral matter typically contains... 

For the asphalt cements produced at that time the adoption of the volatilisation and penetration tests provided some degree of control of excessive changes during plant mixing that might be reflected in more durable asphalts. The adoption of the method for bitumen was intended to provide a means for identifying Trinidad asphalt by observing the amount and color of the insoluble ash. 

The Trinidad Asphalt Lake [situated on the Gulf of Paria, 12 miles west-south-west of San Fernando and 138 ft (43 m) above sea level] occupies a depression in the Miocene sheet sandstone. 

Lake Asphalt. Trinidad Lake asphalt was first reported used for paving in the United States about 1874 (14), and the use of the asphalt from Bermudez Lake in Venezuela soon followed. Trinidad asphalt (3,7) exists in a number of deposits on the island of Trinidad, near the northeast coast of Venezuela. The largest deposit, and the one of chief commercial importance, is an asphalt lake occupying about 0.4 km2 and of uniform composition to a depth of 87 m. As the bitumen is mined, the openings fill in, the level appears constant and an overturning movement of the lake from center to edge keeps the composition constant. This asphalt has been used for pavement constructions and other applications throughout the world. 

The natural asphalt of Venezuela, from the Guanoco area, is also superficially deposited and forms a lake. The covered area is larger than Trinidad Lake, approximately 4,000,000 m, but it has lesser depth (maximum depth, 3 m). The quantities that exist are almost the same as those in Trinidad Island and the asphalt content is approximately 64%. This natural asphalt is not as widespread as the Trinidad asphalt. 

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. 

W. A. AttwooU andD. C. Broome, Trinidad Take Asphalt, 2nded., Baynard Press, London, UK, 1954. 

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). 

Asphalt Asphaltum or Mineral Pitch (Earth Pitch Jew s Pitch or Trinidad Pitch) is a solid or semisolid black or dark brown... 

Bitumen describes a black or dark brown masticlike material that is thermoplastic in nature and softens upon heating. The sources of bitumen are petroleum or coal deposits. The natural product is commonly called gilsonite or pitch, a mineral formed by an old weathered petroleum flow at the surface of the earth that has left behind the larger molecules from the petroleum. A principal source in the past has been Lake Trinidad, a 445,000 m2 deposit on the island of Trinidad. Bitumen from petroleum or crude oil is called asphalt (qv). It is the material left behind after all the valuable compounds, eg, gasolines, have been distilled out of the cmde oil. The amount and quality of asphalt is dependent on the source of the crude oil used in the refining process. Some cmde oils have a higher content of asphaltic bitumen left after the distillation process. Bitumen from coal is coal-tar pitch. It remains after the valuable coal oils and tars have been distilled out of the coal tars produced by distractive distillation. Most industrial applications for bitumen products use asphalt or coal-tar pitch because the supply is more uniform and plentiful. 

ASPHALT (or Asphaltuim). [CAS 8052-42-4]. A semisolid mixture of several hydrocarbons, probably formed because of the evaporation of the lighter and more volatile constituents, It is amorphous, of low specific gravity, 1-2, with a black or brownish-black color and pitchy luster. Notable localities for asphaltum are the Island of Trinidad and the Dead Sea region, where Lake Asphaltites were long known to the ancients. See also Coal Tar and Derivatives and Petroleum. 

The presence of tar sands in North America was notedby American Indians several centuries ago. Pitch recovered from surface deposits was used for waterproofing canoes, It is reported llial Columbus observed asphalt from Pitch Lake in Trinidad and used the material for repairing his ships on his third voyage to the West Indies in 1498. The same bitumen deposit was reported by Sir Walter Raleigh in 1595. For several centuries the material was used for repairing vessels,... 

Many other references to bitumen occur throughout the Greek and Roman empires, and from then to the Middle Ages early scientists (alchemists) frequently alluded to the use of bitumen. In later times, both Christopher Columbus and Sir Walter Raleigh (depending upon the country of origin of the biographer) have been credited with the discovery of the asphalt deposit on the island of Trinidad and apparently used the material to caulk their ships. 

Trinidad asphaltum A natural asphalt found In a pitch lake in Trinidad. Triplumblc tetroxlde See lead oxide, red. 

Asphalt Asphaltum mineral pitch Judean pitch bitumen. Bituminous substance resulting from petroleum by evaporation of lighter hydrocarbons and partial oxidation of the residue. Occurs in West Indies (chiefly Trinidad) Venezuela, Dead Sea, Switzerland, etc. 

Asphalt is a black, bituminous material which is supposed to have been formed as the result of the evaporation and partial oxidation of petroleum. It consists of compounds of carbon and hydrogen, some of which contain in addition oxygen, sulphur, and nitrogen these are mixed with varying amounts of earthy material. Asphalt melts when heated on account of its physical properties it serves as an excellent binding material in making surfaces for roads, etc. The chief source of asphalt is Pitch Lake on the Island of Trinidad, which is 135 feet deep at the center and has an area of over 100 acres. 

Trinickel disulfide. See Nickel subsulfide Trinidad pitch. See Asphalt Trinitrine. See Nitroglycerin... 

Apart from Trinidad and Venezuela asphalt, all other natural asphalt sources were used only occasionally in pavement construction. Today, only a few of the abovementioned deposits are currently exploited (mainly deposits of Albania, Romania and Kazakhstan). The reason is the high cost of recovering the asphalt from the rock. 

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

Because of its chemical composition, TLA is considered as a thermoplastic material. Apart from hardening the bitumen and making it less temperature susceptible, the addition of TLA to petroleum bitumen improves the asphalt s durability, stability, stiffness, anti-rutting performance and fatigue characteristics. TLA is available in semi-solid state or in pellets. Recently, a new product, in pellet form, was introduced and was found to be suitable for warm asphalt mixtures (Lake Asphalt of Trinidad and Tobago Ltd 2014). 

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