Page 29

2014WinShotcreteEMag

Fig. 1: Oregon City Bridge—multiple access methods Fig. 2 and 3: Shotcrete placement inside the arches really lend themselves to either method. The bottom line in this case came down to what the personnel felt the most comfortable with. I don’t find this reason brought up in the discussion very often, but it really should be part of the process. Many contract specifications are written making the choice, and I personally don’t think that is the right answer. The fact is that many jobs can be done efficiently and correctly either way, so the choice should be left up to the qualifications of the contractor. In this case, my personnel and I agreed that we could perform the job more effectively using the Fig. 4: Repairing mesh prior to shoot wet process. At first, I believed that we would do the project using both site-batched bagged material Initial trial batches based on the project and ready mix. After initial testing, I became con- specification seem to function reasonably well, vinced that the ready-mix supplier CEMEX, with but there were definitely some issues. The speci- whom I had a long working relationship, could lend fication called for specific levels of 8% or less invaluable expertise to the project. As it turned out, boiled absorption. The initial test came back at it was a good decision (or maybe just lucky) on my 7.6 to 7.9%, leaving little margin for variation. part, as their ability to provide extensive resources, Secondly, there was a great deal of reluctance to quality information, and testing played a large part allow a hydration stabilizer because it might affect in the success of the project. the bond. The bond was specified at 150 psi Shotcrete • Winter 2014 27


2014WinShotcreteEMag
To see the actual publication please follow the link above