Pavement construction, Sulphlex binders

The flexible binder, Sulphlex-233, was chosen for use in Sulphlex experimental pavement construction in 1980 and 1981. 

The success of SWRI in formulating Sulphlex binders wtih promising laboratory properties prompted FHWA to construct a small pavement section to evaluate the use of such materials with conventional asphalt construction equipment and practices. The goal was to determine if the Sulphlex binders might present unrecognized problems which would argue against their further development ... 

The construction was accomplished by SWRI on a low-volume road at its San Antonio facility in December, 1979. The total pavement is 645 feet (197 m) long, 24 feet (7.3m) wide, and includes ten Sulphlex sections in addition to portland cement concrete and an asphaltic concrete control sections. Three different Sulphlex binders, numbers -233, -126, and -230, were employed in the construction besides the binder type, variables include the binder content, the pavement thickness, and the number of lifts used in the construction. 

For the construction, the Sulphlex binders were produced in nominal 7500 lb (3400 kg) batches in rectangular metal vessels with loosely fitted plywood covers. Two batches of each formulation were required. Details of the production of the binders and of the pavement construction have been reported elsewhere (9). 

The entire construction was accomplished without incident the conventional equipment and techniques worked as well as with Sulphlex binders as with asphalt. After 2.5 years service, at a traffic volume of 1000 ADT (10 percent trucks), distress is evident in a number of sections. In general, the distress has been primarily attributed to poor subgrade drainage placement of certain sections with mix at extremely low temperature (below 65C (150F)) ravelling of dry mixtures and lateral shifting of lifts due to the absence of adequate tack between them. None of the distress is uniquely related to the use of Sulphlex binders in lieu of asphalt cement in the pavement. 

The use of Sulphlex in the future as an accepted alternative to asphalt is predicated on several factors, most importantly (1) a vigorous R D program to optimize the engineering properties of the Sulphlex binders and characterize them for use in pavement construction, (2) evidence of adequate serviceability of the experimental Sulphlex pavements, (3) continuing rise in crude oil price and decline in assured foreign crude oil supplies, and... 

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