TLA - FAQs 

 

 

What is TLA? Define

To date, TLA is the only commercially viable source of natural asphalt in the world. Trinidad is not the only place to boast of a naturally occurring asphaltic deposit and indeed, scattered all over the world are natural asphalt deposits of varying quality, but in terms of commercially global viability, TLA is unique and singular.

 

Where in the world are other natural deposits to be found?

Other natural asphalt-like, or better yet, tar-like deposits can also be found in Venezuela, Indonesia, Canada and the USA.

 

Why is Trinidad’s natural asphalt the only commercially viable one?

Asphalt-like deposits found elsewhere in the world are either below water, of a quality not suitable for use in the road industry or are below the earth such that it can be mined, but at some expense, such as those found in the USA, called gilsonite. Surface mining available to TLA does not only make TLA more cost effective, but its high quality, as sanctioned by global asphalt authorities, also bring merit to its claim of “…only commercially viable.”

 

Where can TLA be found?

TLA possesses its sole origins in Brighton, La Brea. In its crude, unrefined form, it is simply termed “pitch”, or natural asphalt. When refined in its marketable form, it is labeled as TLA.

 

Is the pitch lake inexhaustible? Explain why it is said or thought to be

The pitch lake is not inexhaustible. It is thought to be inexhaustible because occasionally, organic matter, which previously wasn’t there, would appear at the surface, fuelling the thought that it came from below and with it, a replenished amount of TLA. Secondly, its miraculous consistency from place to place on its surface, and over the hundreds of years of use, suggests that it has homogenized by constant motion, not unlike the hand that turns dissimilar constituents in one solution, and that what motivates this turning is the rise, under pressure, of new material from beneath. Thirdly, quantity surveys are conducted from time to time and, despite its rate of extract, its residue is often slightly more than that which the survey suggests that it should be.

 

What is the coverage of the pitch lake?

The pitch lake has a coverage of approximately 100 acres at its surface.

 

What is the current volume of natural asphalt in the lake?

At the current rate of extraction, the last quantity estimate, conducted less than a decade ago, indicated that there was over 400 years of material residing in the pitch lake.

 

Explain the nature of TLA in terms of its:

Crude composition

Refined composition

 

Composition of crude asphalt:

Bitumen:                     37 - 40 %

Mineral Content:        28 - 30 %

                                                                       

Refined asphalt:

Bitumen:                     52 - 55 %

Mineral Content:        35 - 39 %

 

 

Discuss the history of TLA from discovery to date.

Trinidad’s Pitch Lake was “discovered” in 1595 by Sir Walter Raleigh, who, at that time, used it to caulk his ships. This underscores the opinion that TLA is not only a workhorse for conventional applications, but its inherent characteristics, namely sealing and waterproofing, provide for it a great amount of diversity, making it favourable for alternative applications as well.

TLA was eventually used as a neat asphalt for conventional road paving and over the years, millions of tons were sold, peaking during World War II, with a noticeable decline during and after The Great Depression. Eventually, it became favoured as an asphalt modifier, suitable for improving the capabilities and extending the life of refinery bitumen. TLA was stored in wooden, barrel shaped crates that were transported from LATT’s refinery to its wharf via an overhead bucket conveyor mechanism fondly referred to as the ‘Brighton buckets’, where they would be stacked on ships that patiently lined up to be loaded and dispatched literally all over the world. 

Eventually, fibreboard drums became the preferred mode of storing and shipping and are still the medium that is exercised today. The fibre-board drums are stuffed in 20 and 40 foot containers and hauled mostly to Port of Spain and occasionally to Point Lisas, where it departs to its consignee.

 

What is TLA’s first recorded use as natural asphalt?

TLA’s first documented use is in the streets of Port of Spain in 1815.

 

How has TLA’s role evolved over the years?

As previously mentioned, TLA is now used as a modifier to enhance the properties of a bitumen-only pavement. It is now mixed in controlled proportions with refinery bitumen to produce a blend that can yield as much as three times the service life that a bitumen-only pavement is expected to give. 

TLA has almost outdone itself on occasions, since performance specifications, as opposed to product specifications, became popular, asking contractors to produce a HMA that would not necessarily be TLA, but had to perform like TLA. Eventually, it was reconciled that nothing else but TLA performs like TLA and although performance specifications still exist, a substantial bond to cover the cost of repairs, should its performance deliver below expectation, now accompanies it.

 

What is the meaning of ‘penetration’ as applied to the asphalt paving industry?

‘Penetration’, as applied to the asphalt industry, is generally a measure of the hardness or softness of a bituminous binder. Laboratory equipment is used to test a sample of every batch of TLA that can only be delivered if it lives up to a certain penetration. Along with penetration, other parameters are simultaneously delivered.

 

How can TLA conform to a single standard yet deliver a range of penetrations?

By blending in varying proportions, or by mixing with softer (higher penetration) or harder (lower penetrations) bitumen, a wide array of ASTM-designated TLA penetrations can be delivered. The TLA component of the blend remains untampered and uncompromised.

 

How is TLA processed?

Crude asphalt is surface mined and then bucketed in large metal bins close to the lake. It is then mechanically hoisted up to the refinery almost 100 metres uphill, where it is dumped into stills and heated by superheated steam until it is molten, where after extraneous matter is filtered before the TLA is tested, then drummed. The drummed TLA is cooled and stored until it hardens and is ready for containerizing.

 

Who are TLA’s current customers?

Many local contractors have, at one time or the other, used TLA. In the Caribbean, the governments of St. Maarten, Barbados and Guyana have used TLA. Additionally, TLA is currently exported to:

 

What are TLA’s competitors?

Several modifiers/enhancers now exist on the market, and although a lot of them barely live up to minimum specification, their proximity to the end user and their commensurately low performance: price ratio have generated increased market penetration in areas where these products are more readily accessible. 

 

Discuss the use of TLA as it occurs in China today.

China is now LATT’s biggest TLA customer. The Chinese government has seen the merit in investing in TLA and is now using it in preparation for the 2008 Olympics. Other areas currently being paved with TLA are Beijing and Guangdong. 

 

What are the virtues of TLA? Compare it with derived bitumen

The benefits of TLA include:

 

Where has TLA been used in the Caribbean?

In the Caribbean TLA has been used in:

 

 

Where has TLA been used in the Trinidad and Tobago?

To LATT’s best knowledge, TLA has been used:

 

With all of these benefits, are there any limitations to using TLA over bitumen?

Barring the issue of cost, there are only advantages. There is absolutely no drawback to using TLA. Indeed it is more expensive, but when one considers that, at a cost for TLA of 14% more than refinery bitumen, a service life expectation of up to three times as much, a savings to be accrued as a result of reduced maintenance of up to twice as much, and a resulting structural strength and load bearing capacity of up to 40 % more, then, in the context of the total delivered value, there are absolutely no drawbacks to TLA use over bitumen.

 

 

How would pellets assist in the growth and marketability of TLA locally, and regionally?

Pellets represent the next evolutionary step in the life of TLA. TLA would still be available to local contractors, or to those who prefer it, in its current form, but the pelletization of TLA would assist in its marketability by making it available in a form that is both easy to handle and more user-friendly. Local customers will not have to place just-in-time orders for TLA, but can have their limited storage of raw pellets, which are being made to be fed directly into the Hot Mix plant, while regional customers, to whom market penetration has been a perennial problem, will also benefit from this modern form of TLA.