Proctor Cuve on Granular Soils
Proctor Cuve on Granular Soils
(OP)
I have been doing all the research I can on this topic, and I have gotten mixed results. A traditional nice parabolic curve with at least 4 points to find your OMC and MDD on higher fines content soils is great. Works every time. I understand that soils with low fines content should be run by RD, vibrating table. We do not have a table or can find any other labs in the area that do, so we run lower fines soils by Proctor as well D1557.
I have found that the graph never falls or drops on the wet side of the curve, but only goes higher until it reaches the z line and we stop. The last/wet point often is very high in density and does not follow the angle or trend that the curve was going with the drier points. That last point is sometimes a mud puddle. Our Geotechs always want a parabolic curve to submit in reports or to inspectors.
Would it be wrong to draw your curve following the angle of the first two or three points, and fall the curve just before, or on the z line? You would bypass the last wet/muddy point that is abnormally high, to fall the curve where your traditional line of optimum tends to be near the z line. This means that you are extrapolating your proctor curve based on the theory of the test without obtaining a falling wet point. Is this something that is acceptable or should we leave these free draining curves facing concave up without a proper parabola? See attach. Thank you.
I have found that the graph never falls or drops on the wet side of the curve, but only goes higher until it reaches the z line and we stop. The last/wet point often is very high in density and does not follow the angle or trend that the curve was going with the drier points. That last point is sometimes a mud puddle. Our Geotechs always want a parabolic curve to submit in reports or to inspectors.
Would it be wrong to draw your curve following the angle of the first two or three points, and fall the curve just before, or on the z line? You would bypass the last wet/muddy point that is abnormally high, to fall the curve where your traditional line of optimum tends to be near the z line. This means that you are extrapolating your proctor curve based on the theory of the test without obtaining a falling wet point. Is this something that is acceptable or should we leave these free draining curves facing concave up without a proper parabola? See attach. Thank you.





RE: Proctor Cuve on Granular Soils
Check your procedure. Granular materials will generally produce a flatter curve than materials with some fines; however, there is almost always a defined curve in the classic sense. Occasionally we run into a "double hump" curve; however, that is usually on lower unit weight, poorly graded fine sands.
Run your test again and post your results, including the data.
RE: Proctor Cuve on Granular Soils
i believe you should weigh the material after crushing not before .
RE: Proctor Cuve on Granular Soils
Killswitchengage-If you could dig into the solution that you found that would be great! This is a topic that has been a thorn in my side as there are many differing opinions. Thanks to all.
RE: Proctor Cuve on Granular Soils
RE: Proctor Cuve on Granular Soils