| Recently, the epoxy asphalt concrete deck pavement is widely used in Specially long span bridges,for example, Nanjing second Yangtze river bridge, Nanjing third Yangtze river bridge and Runyang Yangtze river bridge. Because climatic condition is one of the most important factors that affect the service life of steel deck pavement , so the application of this technology are mainly restricted to southern areas of relatively high temperature. The minimum temperature in northern areas of China is very low. How to make the epoxy asphalt concrete play its performance, what kind of pavement structure, reasonable mix design and construction technology would be adopted and fit the northern areas ,have an important engineering significance. This article relies on the epoxy asphalt concrete steel deck pavement engineering of the third Yellow River Bridge, The mix design and construction technology of the epoxy asphalt concrete in northen areas have been studied through laboratory test and field test of the road paved, The successful implementation of the project will provide a good reference for the application of the epoxy asphalt concrete in the steel b deck pavement.Epoxy asphalt concrete become an kind of asphalt concrete with high strength and good toughness after curing reaction through adding in thermosetting epoxy resin and curing agent. Epoxy asphalt concrete was originally developed by Shell Oil corporation for using in airport pavement to resist jet fuel and whiff damage, and was used as deck pavement of steel bridge with orthotropic plate of SanMateo Hayward Bridge in United States first in 1967 . Epoxy asphalt concrete is a thermosetting polymer, that is not flowing after curing. This is the most important advantage of epoxy asphalt concrete, because the common asphalt concrete is a thermoplastic polymers, it will become soft when the temperature increases, and can not afford repeating action and extrusion of the traffic load.The epoxy asphalt concrete that just be paved also can afford rutting or pushing, because in bulk production and transportation, the epoxy asphalt concrete has already completed a preliminary curing, and attained a certain degree of stability. The epoxy asphalt concrete should have some characteristics, for example, high strength, stiffness, excellent fatigue properties and good corrosion resistance.The Marshall test method is adopted to ascertain the mix design of the epoxy asphalt concrete, first Volume indicators mixture design is confirmed and Performance test is passed, finally Mineral aggregate grading and the best ratio of stone and oil are confirmed. Because long-span bridge deck pavement has large flexibility, so the performance of the limit bending strain should be prominent in design. Based on the screening results of a variety hot aggregate bins, the epoxy asphalt mixture gradation should be calculated in accordance with the grading scope in design documents. the epoxy asphalt mixture gradation of the third Yellow River Bridge is : 4#warehouse: 3#warehouse: 2#warehouse: 1#warehouse: 6#material: tailing ore = 2.0%:23.0%:13.0%:53.0%:4.5%:4.5%. The ratio of stone and oil is 6.5%.Waterproofing adhesive layer and the bonding layer of steel bridge deck pavement use epoxy asphalt concrete as binder, the epoxy asphalt that used as binder has been mixed by the component A and component BId by weight under the required temperature. The technical indicators and requests of the cured epoxy asphalt should comply with the requirements of the tender documents. The control of spray volume is 0.68±0.05L/㎡ for low bond and 0.45±0.05L/㎡ for Upper bond. For controlling spray volume accurately, skilled operatives Should be ensured to carry out the operation, special person should be assigned for setting up set volume(L/min) , the spray volume per unit area and spray widthon sprinkler machines, the walking speed of operatives should be calculated beforehand. In the spraying process, the operatives should carry out spraying according to this walking speed. At the same time special persons should be assigned for cooperating with supervising engineers check the spraying speed, deviation should be amended in time.Before mixing epoxy asphalt mixture, A and BV in oil tanks of the factory should be pumped to corresponding tanks of mixers. Temperature are set at 87℃and 128℃and continue heating and keep temperature. When the mineral aggregate temperature are controlled within the specified scope, the binder mixture can be joined and mixed. The flux of mixers are set according to the ratio of stone and oil that designed at the scene, and injected into mixing tanks. Dry mix is about 3 seconds and wet mix is not less than 38 seconds. Hot mixture is unloaded into a small tackle and measured the temperature immediately. The mixture temperature should be in the range of 110℃and 121℃. The mixture is unloaded into material movers when its temperature meet the prescriptive scope. After loading asphalt mixture, the tarpaulins must be tightly covered and three metal thermometers that have been calibrated should been inserted in sidewalls of material movers.ABG423 pavers that made in Germany are used to pave Epoxy asphalt mixture, the non-contact balance beams are adopted to control pave by thickness, with the initial compaction and pressing device such as screed Vibration that can be heated and Vibration rammer. The spreading machines should be preheated before paveing work 1 hour ago everyday and the preheated temperature should be controlled between 110℃and 121℃. The side feeders should keep the same speed with pavers. The non-contact balance beams (SAS system) are be used to control the thickness and flatness. The vertical flatness of the armor plates should be measured with four-meter rulers before paving, If the errors are in 3mm, the paver base can adopt the original bridge floor, or hung up lines as base.The mangle rubbing mills are in the wake of pavers. The process pressure include three stages, initial pressure, repressing and final pressure. The rolling style of lower deck is The rolling style of lower deck is 4 times by tire rollers(initial pressure)+ 4 times by Double-drum rollers(repressing)+ 4 times by tire rollers(final pressure). The rolling style of upper deck is 4 times by ouble-drum rollers (initial pressure)+ 4 times by tire rollers (repressing)+ 4 times by tire drum rollers(final pressure).Epoxy Asphalt Concrete should be cured after finished pavement construction. The nature curing method is adopted. A period of curing time is 45 days temporarily. During this period all vehicles are prohibited. |
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