8

I've done several small fence projects before, and hand-mixed concrete in a wheelbarrow for each post as I set them in place.

However, I'm now looking to build a wood guardrail around a parking lot at work, that requires 73 6"x6" posts. I'm going to need about 1.8 yards of concrete for the job. Hand-mixing is definitely out of the question, and it seems that delivered, premixed concrete is substantially less expensive than bags anyway.

I've never worked with a concrete truck before. I know that trucks supply premixed concrete for large areas like slab foundations, but is out out of the norm to have a truck come and fill each hole as we set each post? Of course, I'd have all the holes ready to go with posts in them and a level line set up, but this would still require the truck driving up to and stopping at 73 different spots within the parking lot, to deliver a small amount of concrete to each hole. A lot more time and effort than delivering an equal amount of concrete to a slab.

I've seen rentals of concrete mixing trailers, and of course, the rentable concrete mixers from the big box stores. It seems like there are several ways to skin this cat. What is generally most cost effective, efficient, or both? What would you do?

6
  • 2
    You can get a pumper truck so that it can pump into each hole without having to move the truck. You may consider have a small pile driver come in and drive posts. – Alaska Man Mar 26 at 20:45
  • 1
    Would have everything done before using a truck, all posts in and brace in position. Basic cement trucks have adjustable toughs they can move to position without moving truck too often. There are also pumper trucks with more movement to place cement. Most cement companies will charge extra if you take a long time to unload, a few people with wheelbarrows will do job in no time if truck placed near centre. – crip659 Mar 26 at 20:46
  • 2
    Rent a little motorized cement mixer barrel maybe. Takes the strain off hoeing the stuff, you can load up 1 wheelbarrow at a time and buy the concrete components in bulk and have them delivered on the site. – AdamO Mar 26 at 21:16
  • To me, this is where a moderately serious portable mixer shines (I picked up a 6 C.F. one if I recall correctly.) But I'm not paying your laborers, so from a "at work" POV there might be differences. Definitely get aggregate (sand & gravel, delivered in a pile, or two piles) and cement (powder, 94 lbs) in bags, not sacked concrete mix, if looking to save cost. But again, sometimes the "work math" is different. – Ecnerwal Mar 26 at 22:23
  • If time is not an issue, IMO, the old way is the cheapest way. – r13 Mar 26 at 23:05
11

Delivery of ready-mix in a truck

This gets you a whole lot of mud fast. There are a couple of problems: First, the "short" (small) load fee may raise its cost by 50% compared to the per-yard price you were quoted. Second, they'll likely allow you something like 5-10 minutes per yard to unload the truck and may charge by the minute if you run over time. The unloading process may be sped up if you have several laborers running with wheelbarrows. Third, if the unloading is slow, not only might you pay an extra fee but you might also have the mud setting up in the truck (recall that concrete hardens through a chemical reaction, not through "drying"). This could be mitigated by requesting the mix have a retarder to extend its initial set time.

You-haul ready mix in a trailer

There may be a small-batch concrete provider in your market. They have little 1-2 yard mixer trailers; you bring a heavy-duty pickup truck and tow their trailer to your job site while it mixes. It's heavy; the empty trailer might weigh 3500 pounds and the concrete another 3700 pounds per yard. You could buy just one yard at a time (or even less) and make several trips to ensure that you have relatively fresh concrete throughout the job.

Portable mixer

Honestly.. this is the one I'd do. The main reason is that I frequently work alone or with one assistant, and this approach is the only one I consider practical for such a small "crew." Rent/borrow/buy a mixer large enough to do the concrete for 4-6 posts. (Could buy a used one and resell it when you're through.) Put a pile of sand and gravel on a flat bed trailer along with the mixer, bagged Portland cement, and a few buckets of water. Tow it around the parking lot as the job progresses. You can pipeline the job a bit by dumping the entire mixed batch out into a wheelbarrow or a few buckets -- then you can let the mixer run making a new batch while you're placing the concrete mixed in the prior batch. Size the batches so that the mixing time roughly equals your placing time and all of that is well below the initial setting time.

5

Two yards is a short load in my area, and you pay extra for a short load. On top of that, you don’t have much truck time. By the time you add truck time for 73 stops, you will find the cost is well beyond your expectations. I have a small hand mixer I use when I need a good mix in the hole. At the farm we dump the sakrete and water in the hole and call it good.

For a ready mix truck trailer delivery, you would have to have all the posts set and ready to pour. (You don’t want it to set up in the trailer as they are expensive.)

In my area, we have rental trailers you pull behind a truck for small jobs like this job at just under 2 yards for the mixer type that you probably need; with that many spots, a dump trailer could work, but it would probably start setting up in the trailer.

2
  • 1
    I wouldn't rule out a truck, but yeah you want to check the cost of other methods, if you have a team with wheelbarrows to deliver the concrete from the truck you won't need a pump or need 73 stops of the truck. – Jasen Mar 27 at 3:47
  • I agree a couple of heavy duty wheelbarrows called Jenny’s rented are easier to push and a few helpers can reduce truck time but it will still be longer than a short load time at least in my area. – Ed Beal Mar 27 at 20:02
2

Buy a small electric cement mixer second-hand

The quality of mix is better than mixing by hand in a barrow, and of course is much faster. It'll also be useful for any other projects like paths, footings for walls, and so on. If you've got a large property, it's just generally worth having one.

You can buy new, and they're not too expensive. Cement mixers are tough though, so buying second-hand on eBay is totally fine and will save you a little money. So long as it starts, runs, and the drum isn't full of dried cement as a sign of past misuse (or covered in dents from a previous misuser chiseling out cement), you're good to go.

Sure, you can hire one instead. But if you buy one off eBay, use it and then put it back on eBay, you'll get basically what you paid for it. So hiring one is a waste of money.

1

Concrete aggregate ( sand and gravel at correct ratio ) minus cement.

I get a dump truck load of that and then buy bags of portland cement. The ratio for mixing is 1 part cement, 5 parts navy jack. So one bag of cement will make 6 bags of concrete. Rent a 2 bag mixer and then barrow it to each hole.

0

In the UK we get "Postmix or Postcrete" and it comes in a bag.

Dig hole to correct depth and width relevant to post size. Fill hole approximately a third of depth with water and place post in hole. Pour in postmix evenly around the post until no standing water is visible. Position and level post as required. ... Do not mix postmix with water by hand or machine.

1
  • Having just used some today, it would be a good option for a smaller job, but gets expensive fast, especially if you need more than one bag per hole (poor ground, high fence, or both) – Chris H Mar 28 at 17:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.