Rubber Modified Asphalt Concrete

the non-patented RUMAC system being tested by the New York State Department of Transportation, uses a uniformly graded rubber crumb, and therefore does not require gap grading of the aggregate. The New York DOT is testing this system in highway strips using 1, 2, and 3 percent rubber in total asphalt mix. The results will be compared with results from PlusRide test strips. It is too early for any test results, since the strips were laid in the fall of 1989 (27). 

The asphalt binder used in both types of RUMAC is the same as that used in conventional asphalt. Therefore, conventional equipment is used for mixing the final product. A belt conveyor is used to feed the rubber into the mixer. 

The formula for PlusRide was invented in Sweden in the late 1960s and was patented in the United States by the PaveTech Corporation located in Seattle, Washington under the trade name PlusRide . Marketing is done by several companies across the country. 

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Recycling rubber from tires for use in asphalt pavements is a promising technology. Asphalt pavements incorporating tire rubber are claimed to have twice the lifetime of ordinary asphalt, but they can cost twice as much. Pavements with crumb rubber additives consume over one million tires per year now, and both asphalt-rubber and rubber modified asphalt concrete have considerable potential for expansion. If Federal, state, and local governments promote much broader use and demonstration of this technology, perhaps the technical issues will be resolved and usage will expand. 

Research on the use of crumb rubber in asphalt paving needs to be intensified and brought to a conclusion. Research on newer forms of rubber and asphalt mixtures, some without patent protection (thus available at lower cost), needs to be continued. Research on how asphalt-rubber and rubber modified asphalt concrete can best be recycled should be performed. 

In another study using crumb rubber (size 0/0.7 mm and quantity 15% and 18%), it was also found that the characteristic and rheological properties of the bitumen improved. However, the storage stability requirement of the rubberised modified bitumen (RmB) was not satisfied. When wet and dry processes were compared on extracted RmB from an asphalt concrete mixture (AC 8 mm), it was found that the effect of crumb rubber was more profound when the wet process was used (Lukac and Valant 2011). 

It is noted that the durabihty of asphalt concrete pavements is determined by the time of the trunk cracks formation in the poljmier-containing composites in the modified by elastomers (e.g., by rubber) bitumenous binder of asphalt. Developed by the authors [ 1 ] previously the theory of the cracks propagation in heterosystems has allowed to investigate the problem of the cracks propagation in the rubber-bitumen composite. This investigations show that most effectively to prevent the trunk cracks formation in asphalt concrete can ultrafine mbber particles (150-750 run) in a bitumenous binder of asphalt. 

Thanks to all these properties, the dolocarbonate seems promising for different applications, first of all for all the applications of traditional low density mineral fillers. This material could for instance be used as a component in thermal insulating materials like panels or foams, as a filler in mortars or plasters or concretes to decrease their thermal conductivity, as a filler in polymer or rubber compositions to improve their fire and/or mechanical properties, as a filler in paints, papers, cosmetic compositions, as a rheology modifier (viscosifying agent) in mineral slurries, glues, bitumen or asphalts, polymer compositions, as an ad- or absorbant in different applications such as water or flue gas treatment or even in the field of catalysis, as e.g. a catalyst support, or as a carrier for perfumes, aromas, active substances, medicines... 

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