Feasibility of the use of two spent blast materials as aggregate in hot mix asphalt in Louisiana post-Katrina.

摘要

Using spent abrasive blast material (ABM) in hot mix asphalt to replace part of the fine aggregates used in the production of conventional hot mix asphalt has several environmental benefits. First, onsite storage of spent ABMs negatively impact neighboring properties because the fine materials are a source of airborne debris and dust. Use of tarps as curtains only reduces this hazard. Secondly, storage piles of this waste are situated near canals, waterways and the Mississippi River. Future storms may carry these waste products into the neighboring waterways. Most importantly, these wastes are ultimately disposed of in non-hazardous landfills. Reuse of this waste has benefits that are even important in southeast Louisiana, where massive amounts of hurricane debris and construction-related wastes require vast landfill space for disposal. This thesis is concerned with recycling the spent abrasive materials that are generated at two shipyards in New Orleans, Bollinger Shipyards Inc (Bollinger), and Northrop-Grumman Avondale (Avondale), as opposed to storage onsite at shipyard facilities with subsequent disposal in non-hazardous landfills. The reported production rate of spent ABM from the two shipyards is in the range of 400-600 tons/month. A feasibility study, including physical, mechanical and environmental tests, was performed to evaluate if the waste can be used as part of a modified hot mix asphalt. Two methods, the Marshall Method and Super-Pave Method, were used for evaluating the performance of the modified mix. Consequently, a large number of samples based on these methods have been made and tested. One of the major findings of this study is that the recycling and reuse option is a more desirable waste management option. Waste minimization credit may be given to the shipyard generator of the spent ABM. Preliminary results indicate that this reuse option seems to be both effective and conservative.; An additional part of this research is concerned with the impact of Hurricane Katrina on asphalt pavement life due to submergence in flood water. Two sets of samples were conditioned using water for two different salinity, durations, and heights to evaluate the strength of conditioned specimen by comparing the tension strength of conditioned specimens to that of unconditioned control specimens. Test results are given for specimens made of a conventional mix, a mix modified with 8% of spent coal slag, and a mix modified with 10% of silica sand varying two variables: (1) Salinity; and (2) Storm surge.