Entrained Air

[a3a]

I'm curious if the truck driver was too add water to the mix while on site, would the addition of water have any significant effect on the entrained air. Also, how does the amount of time in the mixer affect the entrained air (if at all) for the case if the truck got stuck in a traffic jam for an hour or so? Are there any other things that could happen after batching but before placement that would affect the air content?

Thanks for any info.

 

[Qshake]

Adding water to the mix on site will affect the air content because of the agitation required following such additions. This agitation is required in most material specifications governing redi-mix concrete delivery.

If a truck has been stuck in traffic for an hour, the mix, when it arrives on site should be rejected. Period. Most specifications governing delivery allow 45 minutes from initial batching at the plant to discharge at the job site. Depending on the cement content of the mix, it may already begin to set up and the driver will know before he gets on site that rejection is waiting ahead. In these cases, its only a matter of where to dump the rejected load. Often times the driver will add water so the concrete doesn't set up on him and will travel to the nearest residential foundation as directed by his dispatcher in order to dump the concrete on an unsuspecting buyer.

 

I hired a contractor to pour light standards on my project. The light standards were augered 9' in the ground. They all seem to be settling and are off a 1" to 2" from level. When the contractor saw this he simply bumped the standards back into place and leveled and tamped. Is this normal? Should they have moved that much? Will they hold 35' ppoles of 600lbs? I am very concerned and have never seen this. Lastly the sepcs called for entrained air and the truck sat for over 1 hour. They mixed water to loosen up the concrete. Do I remove the contractor from my 200,000.00 job? If possible please respond too duneselectric@aol.com. Perhaps you work in this area and could retain a project of over 30,000.00. Please respond. Sincerely, Dunes Management

 

[Ron]

For the light standards, the movement you described is not expected nor appropriate. It indicates a likelihood of poor soil conditions. The contractor's approach to repair was inappropriate as well.

I'm not sure of your location, but light standards must be capable of withstanding several loads, including wind loads. To have that much movement with no significant load is an indication of a problem. I would suggest that you get a local geotechnical engineer to look at the conditions.