Comportamento de misturas asfálticas a quente com agregados provenientes de jazidas de seixo no Estado do Pará.

Abstract

In Belém outskirts and BR316 highway, PA/MA division, and BR010, known as Belém- Brasília highway, the aggregate used in asphalt mixtures is pebble coming from the mines located in Ourem, São Miguel do Guama and Capanema. This work presents the analysis of seven mixtures: three dense and continuous mixtures, in the “C” granulometric zone of the old DNER specification, ES-313/97, moulded with CAP-50/70 link, coming from LUBNOR, Fortaleza/CE and four SMA discontinuous mixtures, with NAPA (2002) granulometry, moulded with CAP-50/70 link from LUBNOR and CAP-30/45 link from REDUC, Rio de Janeiro. The filler used in the mixtures was Portland cement. The mechanical characteristics were defined by the resilient modulus, tension strength, strain under repeated loading and fatigue in compacted cylindrical specimens, according to Marshall method with 50 blows by side. The resilient modulus of SMA mixtures were higher than the dense and continuous mixtures, the CAP-30/45 did not influence the modulus values when compared with CAP- 50/70. The mixtures tension strength presented similar values, with a variation around 7% in the SMA mixture, the link type influenced the results, generating lower values for the mixtures with CAP-50/70 link. In axial dynamic compression, the prevailing factors for obtaining a lower permanent strain were in natura pebble followed by the link content, no matter what kind of link. Concerning the fatigue life in the diametrical compression test at 25oC, the SMA mixtures presented better behaviour than the dense and continuous mixtures. Comparing the fatigue life of the SMA mixtures, the CAP-30/45 provided a better performance than the CAP-50/70. The determination of CBUQ thickness for each mixture, calculated as function of base, sub-base and sub-berth structure and the traffic in BR-316/PA, by FEPAVE, for a period of 10 years and with the production cost by CBUQ ton, established mixture 03, which aggregate was brittled pebble, the better cost-benefit relationship among the dense and continuous mixtures. The SMA mixtures also presented cost-benefit relationship higher when compared with mixture 01, used now in BR-316/PA. The covering option composed by a first CBUQ layer, with dense and continuous mixture, superposed by a second SMA layer, showed to be a good solution.