Pavement sulfur-asphalt

D. Saylak and co-workers. Beneficial Uses of Sulfur in Sulfur—Asphalt Pavements, American Chemical Society, Washington, D.C., 1975. 

The most important use of sulfur is for sulfuric acid production. Other uses range from dusting powder for roses to ruhher vulcanization to sulfur-asphalt pavements. Flower sulfur is used in match production and in certain pharmaceuticals. Sulfur is also an additive in high pressure luhricants. 

Table 2. Properties of Recycled Asphalt Pavement Using Sulfur/ Asphalt Emulsion Binder.

A large number of structural materials were evaluated for possible attack by run-off from a sulfur-asphalt pavement. Of the ten materials studied, copper and steel appeared to indicate a vulnerability. The former or its alloys should never be used in equipment or structures which could bring them in contact with sulfur due to the high probability of producing the sulfates of copper. Steel reinforcing rods would be susceptible to attack by H SO produced by moisture on contact. 

Sulfur-Asphalt Paying Materials (1J, ). Two different technologies are used to combine asphalt and sulfur into a binder that exhibits unique properties and often enhance the pavement performance as well as extend the supply of available asphalt. 

Early field trials were conducted in Saudi Arabia using this technology (22, 23). Considerable interest in sulfur asphalt pavements has been generated, but not projects of significance have been completed. Considerable research and development as well as demonstrations are continuing under the guidance of the Sulphur Development Institute of Canada. 

Utilization of sulfur asphalt pavements in the Middle East appears to have an excellent chance of success. For example, in Saudi Arabia, the production of asphalt in-country has not increased much during the rapid rise of construction activities in recent years. Figure 2 shows the recent and expected production of both asphalt and sulfur in Saudi Arabia. As discussed earlier, demand for asphalt has surpassed the supply. Use of sulfur in pavements may provide the needed binder material and thereby preclude the need for added imports or increased sulfur production(7). 

Construction Procedure. Paving with a sulfur—asphalt hot mix is exactly the same as with asphalt. Conventional dump trucks are used to haul the hot mix from the asphalt plant to the road. There the mix is spread with standard pavement equipment and compacted with conventional rollers. Measurements on the completed pavements verify that sulfur asphalt mixes have good workability and are virtually indistinguishable from conventional asphalt. 

Figure 1. Layout of SNPA sulfur-asphalt binder pavement test, US highway...

Prediction of In-Service Performance of Sulfur-Asphalt Pavements... 

This chapter discusses current research on the use of sulfur in recycled asphaltic concrete pavements. In addition, it describes the results of laboratory tests and theoretical predictions using the latest linear viscoelastic layered pavement analysis methods (15,16) to compare the performance of various sulfur-asphalt concrete pavements with conventional asphalt concrete pavements in a variety of climates. The relationship between pavement distress and performance used in the computer program was established at the AASHTO road test (17). Finally, the results of domestic field tests of sulfur-asphalt pavements are presented along with a discussion of future trends for the utilization of sulfur in the construction of highway pavement materials. 

There are four major considerations in designing a sulfur-asphalt pavement—mix design, construction, performance, and economics. None of these are unique to sulfur-asphalt, but they must all be considered explicitly in order to show under which conditions the new sulfur-asphalt paving material may be expected to be superior to the widely used and accepted asphalt concrete pavement. 

Mechanical Characterization of Sulfur-Asphalt. The serviceable life of a pavement comes to an end when the distress it suffers from traffic and climatic stresses reduces significantly either the structural capacity or riding quality of the pavement below an acceptable minimum. Consequently, the material properties of most interest to pavement designers are those which permit the prediction of the various forms of distress—resilient modulus, fatigue, creep, time-temperature shift, rutting parameters, and thermal coefficient of expansion. These material properties are determined from resilient modulus tests, flexure fatigue tests, creep tests, permanent deformation tests, and thermal expansion tests. 

Characterization tests reported here were performed on combinations of materials needed to evaluate the predicted performance of typical pavements made from conventional asphaltic concrete with limestone aggregate, sulfur-asphalt concrete with limestone aggregate, sulfur-asphalt concrete with beach sand aggregate, and recycled asphaltic concrete pavement with sulfur added during the recycling process. The data... 

Figure 7. Comparison of slope variance for 3-in. thick sulfur-asphalt and asphalt concrete pavements...

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