Crushed Rock density in truck 1

[oldestguy]

If you have measured crushed rock, dense grade base course, 3/4" max. in the truck, your result is requested in tons per cubic yard.

Local rock is dolomite and one contractor says the number is 1.35 tons per c.y. (US)for his material, truck measure. In my past experience I had been using 1.5 t/cy for in-place, but do not recall what I used back when I was closer to this work, using truck measure. Trucks will all be weighed on a local job and the conversion to loose, uncompacted volume will be needed to properly locate the dump areas.

 

[Shwenkerbean]

If you have 1.5 TN/CY in place, 1.35 TN/CY in the truck seems reasonable, depending on the material though, because 1.5 or 1.35 TN/CY seem a little light to me. I'd use something between 1.4 and 1.5 for loose density. The yard where you are getting the base ought to be able to give you a good weight figure.

None of these numbers seem unreasonable, but if you are off a little on big volumes, you've got problems. I'd check with the supplier. One thing to consider is that the supplier can give you a maximum dry density, but really can't tell you the loose denisty in the truck. That number is more of a guess. Depending on the material, you can get quite a variation. That's why for base materials I always work in the in place density when trying to convert weights to volumes. You will know the tonnage you are getting. You never can really confirm the volume unless you field measure regularly.

 

[DarthSoilsGuy]

This method has made all players happy in my experience. All the jobs i've worked on pay yards compacted or cut for unit pricing(not loose)

1 sample mats when delivered
2 run moisture content of mat delivered
3 run proctor specified of mat
4 use minimum specified compaction dry density (benefits contractor $ and is fair so let them know)
5 use #2 and #4 to get your number and convert to tons/yrds3
6 use truck tonnage tickets to get total yardage

if #2 is far off from optimum, the fairness ($) of this method should be reevaluated apart from typical reporting/recommendation duties for wet/dry import materials.

the number of samples for steps 2 and 3 needed so everyone is happy has varied in my experience.

our on-site soil tech would record truck tickets as they arrived so that we felt comfortable independently reporting the total yardage.

 

[oldestguy]

Thanks for the info. So far so good.

This is a low budget job and no testing on site will be done, but observation of compaction is the best we can afford for this one. It is a volunteer job for me at my local subdivision. No extra money for tests (or engineering).

We will, however, be able to make measurements of compacted thickness in a known area to convert that individual truck weight to in-place density if we wish. Then that figure of 1.35 in the truck might be modified so as to have closer control on the rest of the job. Also I suppose the 1.5 figure can be verified or changed.

I'd like to be pretty precise to start with, but we can go back and add gravel where we may have been light on the application thickness.