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Sizing Vibratory Roller 1
- Thread starter AKSherpa
- Start date
Are you doing this for actual construction purposes or for a recommendation in a design report or specification? If for specification, you're skirting on specifying "means and methods" which is better left to the contractor...it adds to your liability otherwise. Give a requirement to meet for the material and its compaction, then let the contractor decide.
If you want to show a compactor range to achieve an engineering result such as uniformity in the upper 3 feet of fill material, then you need to specify a drum diameter and weight range, such as a vibratory compactor having a static-at-drum weight of 10 to 12 tons and a minimum drum diameter of 48 inches. Then specify a minimum number of overlapping passes, say 10 or 20 or 30....whatever you consider you need to achieve uniformity, rather than a minimum compaction.
If you want to show a compactor range to achieve an engineering result such as uniformity in the upper 3 feet of fill material, then you need to specify a drum diameter and weight range, such as a vibratory compactor having a static-at-drum weight of 10 to 12 tons and a minimum drum diameter of 48 inches. Then specify a minimum number of overlapping passes, say 10 or 20 or 30....whatever you consider you need to achieve uniformity, rather than a minimum compaction.
- Thread starter
- #3
We are the contractor and are placing some crushed base rock at an airport that requires min. density = 100% of modified proctor. The last time we placed the same material it seemed like it took way to long to get density. I am hoping to find some sort of publication that lists the size and type of roller recommended for different materials.
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- #5
scott-the Caterpillar Corporation has some good info, but I doubt you'll find much per material.
A key to proper compaction of this type of material is to get the in-place moisture content right before you start compaction. Look at your proctor curve. It is likely fairly steep, which means your range of moisture is extremely small (theoretically would be one point for 100% compaction...but there's actually a range where it will work). I would expect that range to be about 1 percent of optimum, either way. The material will compact better if you start with the material on the wet side of optimum and compact it as it dries through optimum.
Controlling the moisture can sometimes be a trial. If you try to compact this material on the dry side of optimum, you'll beat on it forever and not get compaction. If you get that "magic" moisture content of just over optimum, you'll be surprised how quickly you'll compact with a 12-16 ton vibratory roller. If your base rock is going to be thicker than 6 inches, use two lifts to compact and lightly scarify between lifts.
A key to proper compaction of this type of material is to get the in-place moisture content right before you start compaction. Look at your proctor curve. It is likely fairly steep, which means your range of moisture is extremely small (theoretically would be one point for 100% compaction...but there's actually a range where it will work). I would expect that range to be about 1 percent of optimum, either way. The material will compact better if you start with the material on the wet side of optimum and compact it as it dries through optimum.
Controlling the moisture can sometimes be a trial. If you try to compact this material on the dry side of optimum, you'll beat on it forever and not get compaction. If you get that "magic" moisture content of just over optimum, you'll be surprised how quickly you'll compact with a 12-16 ton vibratory roller. If your base rock is going to be thicker than 6 inches, use two lifts to compact and lightly scarify between lifts.
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