Showing papers on "Rubberized asphalt published in 2004"

Tire rubber in hot mix asphalt pavements

Abstract: In 1989 and 1993, the Wisconsin Department of Transportation (WisDOT) initiated two separate research studies to evaluate (1) the effectiveness of a rubberized asphalt binder mixed with a virgin aggregate gradation for use as an overlay and/or a stress absorbing interlayer, and (2) the recyclability of a reclaimed asphaltic pavement (RAP) containing tire rubber. These studies are presented in this report. Numerous test sections and control sections, of different pavement designs, were constructed for performance evaluations and comparisons. The results and conclusions of the studies are summarized as follows: The construction of the crumb rubber modified (CRM) hot mix asphalt (HMA) pavement and the recycled CRM RAP went fairly smoothly; only minor complications were encountered, primarily due to lack of experience with paving CRM asphaltic mixes, and were easily overcome. Emission data showed that recycling a pavement that contains tire rubber does not appear to pose a threat to the health of the workers or to the environment. All test sections performed comparably with their respective control sections, and no individual test section/pavement design clearly outperformed all others. The inclusion of crumb rubber into a virgin HMA pavement for use as an overlay or as an interlayer did not enhance or impede the overall performance of the pavement, in comparison to a virgin HMA pavement. The RAP mix containing tire rubber was successfully recycled and performed similarly to a new HMA pavement. The asphalt rubber did not appear to increase or decrease the amount or rate of reflective cracking. The inclusion of crumb rubber increased the cost of the rubberized asphalt binder by 76% to 271%, and the CRM mixes by 52% to 117%. A CRM HMA interlayer increased the project cost by approximately $10,000 per lane-mile. Cost savings were achieved when the CRM RAP was milled for recycling, as pavements constructed with RAP are generally less expensive than pavements constructed with virgin materials. With performances similar to standard HMA pavements and higher costs, WisDOT's CRM HMA pavements have not proven to be cost-effective.

Asphalt rubber makes a quiet comeback

Abstract: Asphalt rubber, languishing for want of use since the early 90s, is enjoying a revival as a thin-lift, noise-dampening friction course. The rebound is due to the asphalt industry's quiet pavement initiative. A showcase project is a $34-million noise-attenuation project in Arizona that will surface some 115 centerline miles of Phoenix-area freeways with rubberized asphalt open-graded friction course. California has also been using the technique. Among the forces leading to its comeback are improved tire-shredding technologies, tire recycling facilities in every part of the U.S. and the demonstration in Arizona that crumb rubber modifier is compatible with Superpave performance standards. The new pavements also reduce spray during rainy conditions and are quieter for motorists. Gives a history of crumb-rubber modifier techniques, including schematic of preparation and political developments that resulted in change in policy. Gives specifications on mixes used in Arizona, as well as details of pavement design.

Polymers add performance to asphalt emulsions

Abstract: This article reviews how plastic, or polymer, and rubber additives can provide asphalt chip seals with longevity and the ability to withstand heavy traffic. It describes surface treatments such as polymer- modified asphalt emulsions, which can be elastomeric or plastomeric, and highfloat emulsions. Rubberized asphalt chip seals, in which ground rubber tires are blended with hot liquid asphalt cement, are used to absorb stress and help reduce reflection cracking. Slurry surfacing or slurry seals are a mix of aggregates in an asphalt emulsion which are then applied in a slurry state and yield surfaces that have a smooth finish and high skid resistance. Aggregate and binder are incompatible and can lead to chip seal failure. The article describes a new test protocol that has been developed which may allow for more predictable chip seal performance. It also lists a number of recommendations from a study which showed that chip seals can be effectively used on high-volume roads.

The construction method of drain and bottom of building using mixed rubbernized asphalt with polyurethan resin and stainless drain

Abstract: PURPOSE: A construction method for an underground bottom and a drainage channel using mortar composed of rubberized asphalt and polyurethane resins and a stainless drainage channel is provided to reduce the term and cost of construction and to prevent a water leakage, a crack, sliding, etc. CONSTITUTION: The construction method for an underground bottom and a drainage channel using mortar composed of rubberized asphalt and polyurethane resins and a stainless drainage channel comprises the steps of arranging reinforcing bars on the underground footing bottom and fixing a bar binding ring(6) of the pre-manufactured drainage channel of stainless steel to the reinforcing bar, placing and curing concrete, then applying composite synthetic rubber asphalt resin mortar as a finishing layer(10) to form the surface to correspond to the level of an upper horizontal plate(3) of a drainage channel.