Hey everyone. I got a quick question for a job that my dad is doing. Let me preface it by saying that I've used a hoepac quite a bit, but not quite to this magnitude. He's building an engineered wall and the specs call for 95% on the backfill material, which is just fill dirt excavated to run the geogrid horizontally from the wall. The geogrid must extend 7 feet behind the back of the wall. Dad is renting a 312 for the job and a hoepac to compact the fill. Like I said, I've used hoepacs before with good results. I was on a job last summer and compacted 3 foot deep utility trenches with a Yanmar Vi055 running a backhoe sized hoepac. The trenches were tested for compaction as quite of them were where roadway (parking lot) will eventually be built and all the trenches passed. I can't remember the specs, but they passed. Dad has to hit 95% for the fill material, I'm thinking of having him go in 9" lifts as the geogrid needs to be placed every 18" vertically. Will a hoepac do it? I'm pretty sure it'll be a Cat hoepac, don't know the model though, but it'll be on a 312. Thanks.
I have not run a hoepac much, but it seems that a sheepsfoot trench compactor would be faster and do a better job.
I've been pondering the roller idea, but I don't think I could find one if I tried. The one bad thing about being in a small town is you're fairly limited on rentals. Even a walk behind roller would be tough to find back home. I suppose I figured the hoepac would be the best route given all considerations. It will take longer than other methods, but if we can get 95% or greater with it, that's what we're looking for. EDIT: I think the hoepac is going to be a Cat CVP75, I rented one before and I think that was the size they throw on the 312's as all the rental 312's are running 315 sized couplers. Cat only makes 4 different models, the smallest one being for mini excavators, and the CVP40 looks like it's a backhoe sized unit at somewhere around 8,000 pounds of force. The CVP75 is putting out somewhere around 16,500 pounds of force and 2,200 cycles/min., I can remember the last time I rented one it came with some pretty good thump. I went to Wacker's website and pulled up some specs for a sheepsfoot tench compactor and it seems to me those units put out 7,500 pound of force per drum, so total of 15,000 if I'm comparing things apples to apples. I think the hoepac will handle things, I'd just like a second opinion.
It all depends on the backfill material. Getting 95 should be no problem with a hoe pac and the right material. I would be careful about using native material for backfill. Any job I have done the engineer has required random testing of the backfill when using native fill. Most contractors here use 1000lb plate compactors for this type of work. It helps to have a skidsteer or mini excavator behind the wall to grade the backfill before compacting, it’s important to lay the grid flat with no wrinkles.
Dude.... hoepacking is a science where I work. We run NPK hoe packs where I work, on our crew we have a Deere 270 and a Deere 710. We backfill all the time and hoe pack around control structures and trenchlines all the time. I know when I was taught how to pack I was always told 1" deflection on the rubbers and everytime you move the packer, pick it up, set it down on the next spot and start vibrating. Where I work now we basically do everything you shouldn't do. Most of the guys leave the hoe pack on for long periods of time, we move the packer along the ground like a walk behind plate tamper, we even move it on angles so that it never loses touch with the ground. Our spec with natural ground is 12" lifts, but I have hoe packed 36" with the 710 to 100% compaction in 4 passes. 2 passes each way over each spot, and then slide to the next run and I generally have about 6" overlap on each pass. I tried doing things the correct way, but it works too slow, and I was told to beat on the hoe packs. The main casualty will be the rubbers, but I have found the newer NPK's and the Cat's can take this kind of abuse. With a hoe pack that size you could go a full 12" and then add another 12" which would compact to around 18" or less depending on the manipulation you can inflict with the packer. I borrowed the compaction tester for some testing of my own last year and we made some test pads with a packer to see how effective the hoe packs really are. The 710 with a packer was more effective than our Dynapac CA562 sheepsfoot roller. And our 710's packers are actually bigger than the cat packer we run on our 312B.
Thanks bobcatuser. We have set up testing with the engineer, so the backfill material will be tested as the project progresses and the footing for the wall will also be tested before we lay a single block. The first foot behind the wall is backfiled with spalls I believe, it's all detailed in the plans which I haven't read yet, but everything is explained in detail as to how things are to be constructed. Dad is taking all precautions with this job, he's done lots of retaining walls in the past, this is the first go around building an engineered wall. However, I'm confident he can get things done without any problems. Thanks for the heads up about the geogrid, I figured it would have to be kept fairly flat, but didn't think I'd have to grade it out with another machine. We have a skid steer and a mini as well, I'm sure one if not both machines will be on site so we'll try to get one of them down into the backfill behind the wall. I think the wall is about 8 feet tall at it's highest point and tapers down, no access from the bottom, so I suppose we'll have to bust a road into the backfill area. Burnout, thanks for the info, I appreciate it, that's just the post I was looking for. I know there are a lot of variables going into correct compaction, but with a little common sense about the moisture content, we should be able to hit the spec or exceed it. Like I said with my previous hoepac experiences, I've never failed a test, but I never heard the percentages I hit. I just assumed roadway would be 95% at least and if I could hit that with a 5.5 ton mini and a backhoe sized hoepac, I should have zero issues with a 12 ton excavator running a pretty good sized thumper. I'm cautious with a hoepac, I go a little overkill. I don't run them for seconds on end, a good thump for a couple seconds or until she settles out, lift and move, always overlapping. I don't drag the plate like a neanderthal drags his knuckles, though. :cool2
Drag it around for seconds on end? I think my personal record is around 15 minutes without turning it off. I backfilled a control structure 20ft deep in a few hours with the 710 and an excavator. I had the dirt tossed in and I would just run the packer around like a neanderthal as you put it. Our spec for compaction is 97% until the top 1.5m of subgrade, and then 100% above that. Last year we got a brand new Indeco hoe pack to try out on the 710, it lasted almost 400hrs on the backhoe before the motor seals got cooked and she started spewing oil everywhere, a set of rubbers on average lasts about 200hrs for us. But in any given day of doing services or manholes, our hoe pack is running most of the day doing something. Do you know what the moisture limit is? When I was talking with Mass-X and Hoeman600 at Con-Expo we talked about moisture content and they seemed surprised at our limits so now I'm asking everyone what they are capped at. We had one jobsite last year where we were allowed to backfill until we hiw around 35% on moisture but that was really nice sticky clay. And on the other side of that jobsite I was working in pure silt, the material had no real substance you couldn't even call it sand, and I wasn't allowed to backfill after 13% moisture. Wow I live a sad life..... I get my rocks off over hearing about peoples dirt.... ointhead
I guess I should've been a little more clear. I don't hit the same spot for too long, usually a couple seconds or until the the fill settles out, then I move the plate. I've been known to run a hoepac for 10 hours straight, what fun that is. Don't know what the moisture limit is, as I said I haven't read the plans yet. I will get a chance to speak with the engineer on Wednesday before we get started and I'll get a few things ironed out and good to go. Thanks again for the info.
I always had good luck using a big plate compactor. You need to be careful when using the hoepac you dont push out that face of that wall.
I would think that a 312 with a hoe pac for Chelan dirt is overkill to get 95%.I used a small ride on bomag from Star a few times in Wenatchee,it works great.I could get 98-100 on wet 1 1/4 with 3 passes,that was modified proctor.I would think a 312 would push out the wall for sure.Lay in a lift with the mini,or skid,water,roll.3-4passes with vib then shoot it.
I forgot about Star down there in Wenatchee, might give them a call if need be. As far as pushing the wall out, the 312 will be sitting at the top of the slope, so we won't be running it on the backfill. Probably will have the mini or skid steer down there grading.
Burnout 100% ??...your dreaming....the most you can actually get in-situ is 98% and even that is getting up there...i have never even achieved 100% in a lab let alone on a site.
Lets just clarify, are we talking compaction moisture content or job satisfaction Dont take too much notice of lab results, we're in the real world I've seen what we send to the lab Burnout, you're not sad, your like a lot of us, big kids who love playin in the dirt :thumbsup CascadeScaper, I'll second the comments on being careful of pushing the wall out. I dont know what your wall is faced with, this wall was concrete block, with geo on every 4th layer. Be warned, :Banghead
I don't know how they come up with their numbers. When they figure out compaction don't they just figure out the density as compared to the moisture content of the soil? Most of the guys just do a test with their nuke and then tell me what they got for compaction. I am sure you can get 100% compaction though, I have had a couple sites where they told me we have got 103% on compaction. I'll ask one of the guys tonight how he comes up with his numbers, we're headin out for dinner later. I like to grease the wheels of the compaction guys so that my tests pass, and when they don't we get some leeway with the guys.
You can achieve 100% compaction on a job site. This all depends on what proctor curve the soils tech is using for his nuke guage. It all depends on your soils guy. Some will work with you, others wont. The ones that work with you will want you to do everything they ask for at first. Then they realize that they are 1 not going to achive what they are trying to accomplish. 2 costing all sorts of money 3 holding back progress. Ive worked with both types. Running an 815 running a fill, you learn what each one wants. When hes checking compaction, you cant be running your fill, so you should hop out and talk to him. If your not making the numbers, ask him what he wants you to do. If that doesnt work, after some experience, you can run some suggestions back at him. Then again, it all depends on material. In sand, ive backfilled 15 foot deep ditches, filled em to the top. Pile an extra 2-3 ft on top of the trench line. Start pouring the water to it and hit it with the plate packer. It settles right to where you want it, you hit the numbers dead on the nose. Ive run fills on building pads with blue clay. Tried and tired and tried. Couldnt get over 96%. Changed the proctor, hit our 98% requirements. Then the footing crew came in to start digging footings. They could BARELY dig thru that stuff. It moved and moved when we put it in. Sun hit it for a few days, hard as a rock
The compaction testers we have are normally pretty good. Most of our track loader operators and dozer operators hate these guys. Last year I tried making friends with em, bought a couple of em lunch, drinks and coffee. It didn't take long and now we all get along. Even if our tests didn't pass, or the moisture content was a little high we would work together and figure out a plan. Now the guys hardly check my work, they stop by take a test every lift and at coffee they usually go pick up our coffee for us. There is definately something to be said for playin friendly like in the dirt with others.
were i an inspector/soils engineer...i'd drag all the contractors into a prebid meeting...let them know that i will give them 4 density tests for free for them to gauge what it takes to attain the desired density....and then let them go, not show up until job was finished....with the understanding that we would take tests after the fact at 25' intervals, "talking about water/sewer construction"...at random depths....should it fail, the contractor would dig down to within 2' of the top of the installed pipe 25' each way of the .failed test, and recompact until it did. i've seen too many streets fail where there supposedly was documentation where all the density tests passed....very easy to make another pass on what your compacting when you see the soils tech drive up and make it go, 6' below that might it be a long way from meeting spec. this way, all contractors will know what is expected of them, will do the proper job of compacting, and we all can bid/get paid accordingly. it might be worth the contractor's time to have his own full time soils tech onsite.
Dont get to close to the face of the wall it will move. Look at your specs there is a wieght limit on the compactor within 3' of the wall. I know with keystone there is a limit.
agree with over 100% er's I agree with those folks who claim to get nuke readings over 100%. If my soils memory hasn't completely left me, we use 2 types of proctors down here, Standard proctor using a 15 lb(?) hammer and a modified proctor with a heavier hammer. Moisture curves i've examined provide maximum dry density based on the standardized load applied(compactive force of the std. proctor weight or modified weight). Given a larger compactive force, the max. dry density computed/reached may be higher than that of the "standard". agree with all the statements previous related to avoiding wall pushouts due to compaction. Recommend smaller lift thicknesses (easier to reach density, less lateral force to push out wall). Maybe i just repeated what a bunch of folks just said- if so, i'm sorry to be Mr. Copycat.
Thanks everyone. We're going with low lifts just for the push out factor. The engineer has been awesome to deal with and we have set up a schedule with them for testing. We will not compact within 3' of the wall due to pushout as well. Things are going well thus far.
Anything yet there cascadescarper?