""""somearea under structure(Not under landscaping paver) where is difficult to compact."""" ---I do not quite understand what this means.

jameschen6(梦想农庄-雨水多好)

Footing should be on native undisturbed soil. If the soil is not strong enough, you have to excavate further until the capable soil. Fill the hole with lean mix before the concrete footing. You need to tell the supplier that the lean mix will be for footing (may ask 1 MPa?). Otherwise the supplier will give you less kpa likely (less than 400kpa) although labeled with 400kPa. They assumes that you will cut/chip it later.

Can you fill the hole with same concrete if you do not care for the cost? This mean to have footing 250 mm depth in some area and 1000 mm in other area for instance. To be conservative, ask structural engineer.

By the way, you work for yourself?

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Last Updated: 2012-8-14
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From my limited knowledges -jameschen6(梦想农庄-雨水多好); 2012-8-10 {1302} (#7709017@0)

本文发表在 rolia.net 枫下论坛HPB is more like a trade name than a specified material. There is no standard provincially and municipally now for it (Brampton may have in the old day. they still use it now?).

I guess the name is from its use at water main bedding. You need to place HPB before you lay the water main pipe at the trench base. It is my understanding that the pipe can be fairly better supported curvedly on the HPB instead of theoretically and linearly supported by the soil base. I had only one project of watermain. I saw the practice.

In addition to above, two of our small projects are stone pavements on a structural concrete deck of underground parking garages (Condominiums drive circle). Installation sequence upwardly is structural concrete slab - geomembrance - protection board - HPB - geotextile (270R) - bedding sand - stone pavers. The catchbasins collect all surface run off and all water in the HPB. The purposes of the HPB here are 1) free drainage of water; 2) to aviod any compaction effort on the structural decks.

In a house or building constructions for either subfloor or perimeter drainages, Perforated pipe was covered IN ALL SIDE with 20 MM CLEAR STONE (NOT HPB - You can but waste of money) and WRAPPED WITH GEOTEXTILE 270R.

I have never seen people use it for road base myself.更多精彩文章及讨论，请光临枫下论坛 rolia.net

Thanks James. HPB is a trade mark of Dufferin aggregates. Their sales happened to be in my office today. Xiao C, could you please provide any information about Canel usage of HPB? -maxiaohong(狗拿耗子); 2012-8-10 {747} (#7709341@0)
He said that HPB(TM) only can be used by Dufferin. I did check other aggregate supplier's quote, they were called 6.7(6.3) Chip stone. HPB(TM) is a washed crushed limestone with the grading of 6.7. It is used on piping, and backfill material for retaining walls, landscaping pavers as you said for drainage purposes.

Thank for sharing the information about some area arround structure using HPB. It is reasonable when compaction is a problem.

Our last project with Brampton, city refused our proposal of using HPB to be pipe bedding. Cost wise, Material cost of HPB is Slightly higher than A, However since it saved labour cost for compaction, for project cost, I do not think it should make any difference unless Filter cloth is required.

Very good. Dufferin Aggregate HPB is 100% passing 9.5 mm and <3% passing 0.075 mm -jameschen6(梦想农庄-雨水多好); 2012-8-10 {511} (#7709396@0)
I agree with you except the last point you made. Once you use HPB or 20 mm clear stone (fines have been removed from these two materials). You need to separate the material from normal soil by using geotextile. Otherwise the fine particle will migrate, and result in soil loss and settlement. On the deck or behind retaining wall, people do not want to compact. Use HPB (or 20 mm clear stone) is good, but use it together with geotextile. You can use it to save on the compaction cost. Again use geotextile too.

So your recommendation is using HPB along with Geotextile in all cases, am I right? -maxiaohong(狗拿耗子); 2012-8-10 (#7709407@0)

At all cases where you have it directly on or under the soil type which comprises of fine particles. The geotextile need to be at least 270R -jameschen6(梦想农庄-雨水多好); 2012-8-10 (#7709428@0)

Thank James. I think you are right. Why don't you write something about this opinion and publish it. I do not think that all engineer understands this. -maxiaohong(狗拿耗子); 2012-8-10 {391} (#7709454@0)
We did put lots of HPB underground, and later on with maintenance problems without geotextile. I believe one of the reason is that this is still a relatively new material with both advantage and disadvantage. We still have the design drawing of HBP required in our project today without requirement of geotextile. Hopefully you may add this knowledge of gap to the industry. Just a thought.

很稀饭你们的对话。羡慕极了。 -c_w(cw); 2012-8-10 (#7709456@0)

Xiao C, Would you like to be a part of this discussion. Any information you know about the Canal usage on HPB? -maxiaohong(狗拿耗子); 2012-8-10 (#7709492@0)

I wanted to but I can't. I am not a Civil/Geo guy. My knowledge is super limited. LD is the Civil person and he has done some drainge/underground utilities. Compaction, retaining walls, bedding stones, 57 stones, cement, he knows these stuff. -c_w(cw); 2012-8-10 (#7709505@0)

I saw a lot of existing cases without geotextile. That is not good. I have to leave for a Christian Camp. Talk with you guys on Monday -jameschen6(梦想农庄-雨水多好); 2012-8-10 (#7709756@0)

Entertain and be safe. -c_w(cw); 2012-8-10 (#7709765@0)
Nice talking to you. I would like to discuss in structural usage too if you agree next week. Have a nice weekend and enjoy your off time. -maxiaohong(狗拿耗子); 2012-8-10 (#7709786@0)
Hi James, I found that there is somearea under structure(Not under landscaping paver) where is difficult to compact. I think regular practice is lean mix conc., is HPB acceptable when access is a problem? Do you have any experience for it? -maxiaohong(狗拿耗子); 2012-8-13 (#7715192@0)

""""somearea under structure(Not under landscaping paver) where is difficult to compact."""" ---I do not quite understand what this means. -jameschen6(梦想农庄-雨水多好); 2012-8-14 {675} (#7717353@0)
Footing should be on native undisturbed soil. If the soil is not strong enough, you have to excavate further until the capable soil. Fill the hole with lean mix before the concrete footing. You need to tell the supplier that the lean mix will be for footing (may ask 1 MPa?). Otherwise the supplier will give you less kpa likely (less than 400kpa) although labeled with 400kPa. They assumes that you will cut/chip it later.

Can you fill the hole with same concrete if you do not care for the cost? This mean to have footing 250 mm depth in some area and 1000 mm in other area for instance. To be conservative, ask structural engineer.

By the way, you work for yourself?

I work for civil contractor. Our structure is underground and heavy, that is why lean mix is always required under conc. footing or slab. -maxiaohong(狗拿耗子); 2012-8-14 {410} (#7717518@0)
15MPA or sometime 0.4mpa unshrinkable fill are required under base slab. So My question is when there is 2rd level of slab, sometimes, the access is limited, compaction is a problem, in addition, time is a issue when water shows up. So I am thinking of use HPB to fill this void area to ease the construction and speed up the time especially when shrinkable fill required. What do you think if you do not mind?

I do not quite understand your situation. Do you mean to use HPB instead of U-fill? I guess you cannot. -jameschen6(梦想农庄-雨水多好); 2012-8-14 (#7717984@0)

Thanks, I discussed with our carpenter today, we may leave the formwork in place while we can do walls beside it. -maxiaohong(狗拿耗子); 2012-8-15 (#7718612@0)

我没有记得见过这个做 ROAD BASE。我见过多的是在 CANAL 的 BANK 上，在 SLOPE 很小，接近路面的地方有这样的。SLOPE 大的地方，用 RIPRAP。好多 LEVEE 上没有 PAVING/CONCRETE，用的是小的 SHELLROCK。-- 不入流的说法。 -c_w(cw); 2012-8-10 (#7709106@0)

晚上我请教一下 LD。我记忆中这种石头好像很沉，而且颗粒和粉末共存似的，这样对 DRAINAGE 是不好的吧？ -c_w(cw); 2012-8-10 (#7709112@0)

Dufferin Aggregate HPB is 100% passing 9.5 mm and <3% passing 0.075 mm -jameschen6(梦想农庄-雨水多好); 2012-8-10 (#7709363@0)

这么细节的东西，我就不知道了。好奇，等我问问领导，看他怎么说。 -c_w(cw); 2012-8-10 (#7709370@0)

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""""somearea under structure(Not under landscaping paver) where is difficult to compact."""" ---I do not quite understand what this means.

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