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Density and Voids Determination - 14070_315
QUESTIONS - 14070_317

Engineering Aid 1 - Advanced Structural engineering guide book
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Figure  13-37.-Marshall stability testing head mounted in CBR jack. however, we’ll briefly discuss the method here. The apparatus used for testing stability and flow of the specimen is shown in figure 13-37. This figure shows a Marshall stability testing head containing the specimen, mounted on the plunger of a bearing-ratio jack. This test head consists of upper and lower breaking heads. A 5,000-pound proving ring with a dial is installed in the jack.The test for stability is made by applying pressure gradually, about 2 inches per minute, and reading the maximum pressure the specimen sustains before failing. The  test  for  flow  is  carried  out  simultaneously  by holding a flow meter over the testing head guide rod (vertical rod shown running through the testing heads) and  reading  the  meter  at  the  instant  the  specimen  fails under  pressure.  This  reading  indicates  the  flow  value  of the specimen in inches to the nearest 0.01 inch. HAZARDOUS-MATERIAL PRECAUTIONS Although the Navy has exacting definitions for the terms hazardous material, hazardous chemical, and hazardous substance,  let’s, for simplicity of discussion, lump  them  all  together  and  simply  say  that  these materials,  because  of  their  quantities,  concentration,  or hazardous  properties,  pose  a  substantial  hazard  to human safety and health or to the environment. The risks associated  with  these  materials  include  flammability, toxicity, corrosivity, and reactivity. From your study of this chapter and the EA3 TRAMAN, you should be able to see readily how many of the materials you test, or use for  testing,  in  the  laboratory  fall  within  the  above definition. Heated asphalt can cause severe burns if allowed to come into contact with the skin, and asphalt cutbacks  are  highly  flammable  with  low  flash  points. Some of the chemicals that you will use in materials testing are highly toxic and corrosive. Others react with water, forming explosive gases; however, not all of the hazardous materials that an EA uses are confined to the laboratory.  For  example,  the  ammonia  used  with reproduction equipment gives off highly toxic fumes. For these and other reasons, all such materials must be handled, used, stored, and disposed of properly and with caution. As a crew leader, you must recognize the threat that hazardous materials pose to all personnel present on the jobsite and take action to prevent mishaps. Material  Safety  Data  Sheets  (MSDS)  must  be received and maintained for all hazardous materials in your work space. The MSDS identifies any hazards associated  with  exposure  to  a  specific  material.  It identifies  personal  protective  equipment  and  other safety precautions required as well as first aid or medical treatment required for exposure. By federal law, a crew leader is required to inform his or her crew members of the risks and all safety precautions associated with any hazardous material present on the jobsite. A good time for you to do this is during your daily standup safety lectures. A safe practice concerning hazardous materials is to not draw more material than will be used in 1 day. Storing hazardous materials in the workspace or on the jobsite  requires  the  use  of  approved  storage  containers. Some  of  these  materials  require  separate  storage;  for example, flammable materials and corrosive materials cannot be stored together. When in doubt about storage requirements, consult with your supervisor or the safety officer. Excess hazardous materials or hazardous waste products must be disposed of through an authorized 13-50







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