Proof-rolling. 1

[sayler]

Proof-rolling has often been suggested as an alternate method for compaction testing. If the material lift is 8-12", near optimum moisture and the compaction effort ( weight / amplitude / pattern ) is adequate, what criteria should be used for interpretation, with respect to material type; crushed top courses, pit runs, clays / silts, etc ?
I'd appreciate your input.

 

[BigH]

Proofrolling to me has always been done with a purpose of
(1) identifying soft spots in the subgrade (of a road or building footprint with slab-on-grade) and
(2) ensuring a "uniform" density in the uppermost zone of the natural stratum.

It has never been done to obtain a specific degree of compaction. I've seen this specified and have always wondered why it is so - if you aren't happy with the material at the founding level, you shouldn't have designed for it to be at that particular level.

 

[dgillette]

Looks like you two are using different definitions of "proof rolling." Like Big H, I've always used the term to mean testing of the foundation before putting in embankment fill or a structure. I would call what Sayler is talking about a "test fill." Pick the criterion you want to design for (e.g. 95% std., 70% RD), and experiment with what equipment, moisture, no. of passes, etc. you need to get that. For coarse materials, you might not be able to measure densities without a huge water-filled ring test (analogous to a sand cone test) or come up with a really credible maximum density, so you experiment to see what you can get with typical equipment and procedures, and go with a procedure spec instead of a performance spec. ("...shall be compacted by a minimum of four passes of a 10-ton vibratory roller, with lift thickness not to exceed 18 inches loose..." VS "...shall be compacted to achieve density equal to or greater than 95 percent...")

 

[cvg]

thread261-137601

try this for a little more info on how to conduct and quantify your proofrolling tests