Asphalt concrete pavement

Asphalt concrete is primarily used as a structural pavement surface constructed over a subgrade and a subbase. It is designed to support the traffic load and distribute the load over the roadbed. Asphalt concrete pavements can be constructed using hot mix or cold mix asphalt. Hot mix asphalt is a mixture of tine and coarse aggregate with asphalt cement binder that is mixed, placed, and compacted in a heated condition. Cold mix asphalt is a mixture of emulsified asphalt and aggregate, produced, placed, and compacted at ambient air temperature. Cold mix asphalt pavement usually requires an overlay of hot mix asphalt or surface treatment to resist traffic action. 

Saylak, D., Gallaway, . M., and Epps, J. A., "Recycling Old Asphalt Concrete Pavements", Proceedings of the 5th Mineral Waste Utilization Symposium, Chicago, 111., 13-14 April, 1976,... 

One and one-half miles (2.4 km) of existing asphaltic concrete pavement on Loop 1604 were overlaid with an inch (25.4 mm) thick Sulphlex mixture The Sulphlex hot-mix was produced in a three ton (2.7 tonne) batch plant, and hauled approximately five miles (8.05 km) in open trucks to the construction site. 

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. 

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...

The U.S. Bureau of Mines participated in a field trial of sulfur-asphalt concrete pavement on U.S. Highway 93 near Boulder City, Nev. in January 1977. This test section is 2100 ft long. The aggregate-asphalt-sulfur (AAS) system was used to mix the ingredients. The sulfur and AC 40 asphalt cement were introduced into the pugmill as individual components. The sulfur comprised 27 w/o of the total binder. The aggregate used in the mixture was a crushed volcanic rock which conformed to the Asphalt Institute type IVb gradation. This test section is now in post-construction evaluation. 

Saylak, D., et al., Recycling Old Asphalt Concrete Pavements, Proceed-... 

INVESTIGATION ON DETERIORATION OF RECYCLED HOT-MIXED ASPHALT CONCRETE PAVEMENT AND A TRIAL RERECYCLING OF ASPHALT CONCRETE... 

Keywords Asphalt concrete pavement, durability, pavement recycling, recycled hot-mixed asphalt concrete, re-recycling. 

Discussion of Results. The results of the relative fatigue life analysis of the four pavement sections are given in Table X. The analysis indicates that the 12-in. asphaltic concrete pavement (System 1) and the 1%-in. sulfur-asphalt over 10-in. asphaltic concrete base (System 4) were not able to withstand the 106 passes of an 18-kip axle load. For System 4, the iy2-in. S-A-S surfacing was adequate, but analysis indicated that... 

In Japan an oil-absorbing artificial aggregate is reportedly manufactured using CKD that is used to improve the rutting resistance of asphalt concrete pavements by absorbing the lighter fractions of excess asphalt cement binder during hot weather... 

Chehovits J. and L. Galehouse. 2010. Energy usage and green gas emissions of pavement preservation processes for asphalt concrete pavements. 1st International Conference on Pavements Preservation. Newport Beach, CA. 

Monismith C.L. and A.A. Taybali. 1988. Permanent deformation (rutting) considerations in asphalt concrete pavement sections. Proceedings of the Association of Asphalt Paving Technologists, Vol. 57, p. 414. Williamsburg, VA. 

The determination of the thickness of a full-depth asphalt concrete pavement is carried out from a similar to a flexible pavement with unbound layer nomographs. A sample of the nomographs used for 15.5°C MAAT is shown in Figure 13.4. 

Figure 13.4 Nomograph for thickness determination of full-depth asphalt concrete pavements. (From Asphalt Institute, MS-1, The Thickness Design, Asphalt Pavements for Highways Streets, Manual Series No. I [MS-1], 9th Edition, Lexington, USA Asphalt Institute, Reprinted 1999. With permission.)...

The determination of full-depth asphalt concrete pavement thickness, T , of a theoretical new pavement, is carried out from the nomograph given in Figure 13.4, by knowing the subgrade strength (resilient modulus, Mr) and the cumulative future traffic for which the overlay is designed for (in equivalent standard load, ESAL). 

The temperature adjustment factor for a three-layered asphalt concrete pavement (asphalt, unbound aggregate layer and subgrade) and for a full-depth pavement can be determined from Figure 16.41. 

Figure 16.41 Benkelman beam deflection adjustment factors owing to temperature variation for full-depth and three-layered asphalt concrete pavement. (From Asphalt Institute 3rd Edition, Asphak Overlays for Highway and Street Rehabilitation. Manual Series No. 17 [MS-17]. Lexington, US Asphalt Institute. With permission.)...

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. 

The constant interest in elucidation of new possibilities to increase of the asphalt concrete pavements durability continues to persist for several decades. Such pavements are composites consisting of gravel, sand and the polymer-containing composite (bitumen) in rationally chosen ratios. According to modem notions, it is assumed that the durabihty of asphalt concrete pavements is determined by the appearance of numerous major tmnk cracks in the pavement. This conclusion is confirmed, in particular, in numerous reports (over 130), presented at a special conference devoted exclusively to the problem of cracking in pavements [2]. It was shown earlier and in reports of the conference that a certain increase in the durability of pavements can achieve by introducing into the bitumenous binder of elastomers (synthetic mbbers or cmshed technical mbber). However, very important question about a quantitative determination of the optimum size of elastomers particles introduced into the bitumen for providing of maximum durability of pavements, until recently, remained open. The theoretical solution of above problem is presented in the next section. 

The glass-ceramic fillers produced were mainly used as an additive to asphaltic-concretes for constructing upper layers of clarified pavements. Asphaltic-concrete pavements with glass-ceramic fillers have such advantages ... 

Using asphaltic-concrete pavements with glass-ceramic fillers increases pavement roughness, therefore decreasing vehicle braking distance and improving traffic safety. 

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