[b]Tests for lightweight agg in Normal Wt Agg[/b]
[b]Tests for lightweight agg in Normal Wt Agg[/b]
(OP)
Colleagues:
We have a situation where boulders are being used to produce coarse aggregate. There are occasional pumice-type boulders in the area and unless the crushing operator is "on the ball" some of them get into the mix. What test can I run on the aggregate to determine the percentage of aggregate that has a specific gravity of, say, less than 2?
We have a situation where boulders are being used to produce coarse aggregate. There are occasional pumice-type boulders in the area and unless the crushing operator is "on the ball" some of them get into the mix. What test can I run on the aggregate to determine the percentage of aggregate that has a specific gravity of, say, less than 2?





RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
Apparently, you feel your situation should not have an excessive amount of pmice. Fine pumice can act as a pozzolan in concrete.
Do you have an idea of what percentage of pumice would be detrimental for your needs? Are there other options for the boulders to be crushed?
Light aggregates like pumice usually crush easily and can further be degraded into fines by either poor or excessive handling. - In other words, it is a dynamic problem and the sizes may change after the point of sampling (even into the mixing process).
Because of this, you should look for decreases in the average specific gravity of the smaller fractions of the finished aggregate at a consistant location in the process. You will have to separate the sample by gradation, looking at the smaller non-dust particles and determine the specific gravity. Do not expect a high degree of accuracy because some fractured pumice may absorb water very quickly, complicating the tesing and skewing the particle density.
It is not an easy or cheap task because of the variability of the properties of pumice. - I had a number of #4 sized Greek pumice particles floating in my aquarium for over 4 years, so it does not necessarily absorb water quickly in some cases.
This is one of those concrete engineering problems you wish you could spend more time on.
Dick
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
Maybe whoever's providing or testing your aggregate has got a copy they could lend you. It's only three or four pages.
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
A personal membership is now less than $100 and entitles you to a book of standards that costs substantially more than the dues. You also get on-line downloads for items in that 200-400 page books of similar subjects. You also get a member discount on other standards that any firm would be glad to reimburse you for.
Join a committee on a subject and you may be able to get great opinions from people in that area. It took me 15 or 20 years to get to be a voting member on the committes that I was interested in, but I learned a great deal while being involved.
They have comprehensive standards on everything from baloons and party hats to construction materials and electronics. - I first got involved when working on the Saturn program and I respect the professionalism and international credibility.
Dick
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]
I have done the 'lightweight particles in aggreagte' test, and it is typically used to find/identify lignite [brown coal] in sand and gravel deposits [typically of glacial otigin]. In order to find material with a density of less than 2.0 Mg/m³, you would need a 'liquid' with a density of at least 2.0 Mg/m³.
The test itself is very simple, you make up the liquid of the appropriate density, pour in the aggregate, aggitate, then remove any material which floats, dry and determine the percentage of the original sample. Over-simplified for the response, but you get the idea.
As this is likley to be very difficault [nigh on impossible!], have you considered determining the relative density of the parent material with varying percentages of pumice. This will have a number of advantages
1. You don't have to manufacture a liquid with a very high density [likley to be paractically impossible and still get the liquid to be thin enough to work]
2. It should be possible to graph the results, then by measuring a set dry mass of the aggregate, placing this in liquid and determining the volume of water displacment you can rapidly asses the percentage of pumice. Nice and repeatable on site using pre-marked measuring cylinders after a little bit of calculation/experimentation.
RE: [b]Tests for lightweight agg in Normal Wt Agg[/b]