Timeline for Testing Density

[Crazyson]

Here is my situation: Small concrete paving project. Once the project starts, the existing concrete paving needs to be torn out and replaced quickly. Contract says that the 6” aggregate base must be compacted to 95% Modified Proctor. As I understand it, there are two components to measuring the in place density of the new aggregate base….The on-site portion and the laboratory portion.

The on-site portion I understand will likely be measued by a nuclear density gauge. No problem there.

However, an ASTM D-1557 (Modified Proctor) Moisture-Density Relationship test of a representative sample of the aggregate must be performed before the on-site portion can take place. How do I efficiently schedule the testing lab? Does the contractor need to stockpile his aggregate on site, then have the testing agency come out and grab a sample, spend a few days in the lab, and then start work? Seems like a lot of waiting around to me.

So…could someone please explain the process/timeline for measuring the density of an engineered fill? I'm trying to be as efficient as possible once construction starts, but I'm new to the soil testing game.

Thank you.

 

[dgillette]

The lab work can be turned around in a few hours if you have a technician standing by ready to pounce, and you are starting with material that is dry of optimum so the bag sample doesn't have to be dried. Microwave drying to get the moisture content is generally accepted and it's a whole lot faster than oven drying. Don't know if ASTM has a standard for microwave moisture content; USBR does have one.

 

[TDAA]

ASTM does have a standard for that. ASTM D 4643-93

What is to stop you from obtaining samples at the plant? I am sure they are not going to crush the rock, and convey it directly to the truck. Go to the quarry that will be the supplier, and obtain samples from stockpiles using approved ASTM methods.

Also, the plant will likely have curves for the typical stone they produce. Ask for them, and you will see you will be shooting for. Back that up with your own testing if you feel the need, or are required to by the project specs.

They likely have a wealth of information on the stone at the quarry. You can "use" the data, even if you dont trust it completely.