pea gravel vs 89 aggregate

[gte447f]

I have a job where PVC stay in place wall forms will be used. The forming system supplier's literature says to use a "pea gravel" 4000 psi concrete with a slump of 4-5. I indicated "pea gravel" coarse aggregate on my drawings. I have received a concrete mix design submittal that is using 89 stone from a limestone quarry. I am satisfied that the 89 gradation is appropriate for the intended usage as far as size goes, but should I request that naturally weathered, rounded gravel be used instead of crushed limestone? Natural river bed gravel is my interpretation of "pea gravel", but I am not aware of an official definition. Because of the nature of the leave in place forms, I assume the mix will need to pump well and "flow" well inside the forms because of congestion and minimal if any vibration. Will rounded pea gravel be better for this application than angular crushed stone?

 

[dik]

I would check to see if 3/8" aggregate can be used. The pea gravel will make the mix more 'fluid' and may be compensated by using SuperP. I like angular aggregate... seems to hold up better.

Dik

 

[wannabeSE]

I would go with ACI CT-13 Concrete Terminology definition for Pea Gravel: "screened gravel, most of the particles of which pass a 9.5 mm (3/8 in.)sieve and are retained on a 4.75 mm (No. 4) sieve." It doesn't mention rounded or weathered.
The publication is a free download

https://www.concrete.org/store/productdetail.aspx?ItemID=CT13&Language=English&Units=US_Units.

 

[dik]

Thanks Wannabe... in these environs, pea gravel is rounded aggregate and clean. Still need a gradation, else too much cement and shrinkage.

Dik

 

[gte447f]

wannabeSE, thanks for the link. In the same document (ACI CT-13), gravel is defined as "aggregate retained on the 4.75 mm (No. 4) sieve and resulting either from
natural disintegration and abrasion of rock or processing of weakly bound
conglomerate". The word gravel is also used in a few other places where it seems to be distinguished from crushed rock and where it seems to be insinuated that it is a naturally occurring rock of a certain size, such as the definition of aggregate ("granular material, such as sand, gravel, crushed stone...") and the definition of coarse grained soil ("soil in which the larger grain sizes, such as sand and gravel, predominate"). So, is gravel, and thus pea gravel, naturally occurring by definition?

 

[gte447f]

I have inquired with the forming system supplier whether #89 crushed limestone is acceptable or whether naturally weathered, rounded aggregate is required. I will let the forum know their response.

 

[jgailla]

In Florida, limestone is not considered rock.

 

[gte447f]

jgailla, this aggregate is from a state DOT approved limestone quarry from your next door neighbor.

 

[gte447f]

I received a reply from the wall forming system supplier. They said their recommendation for pea gravel is intended as a reference to aggregate size and that 3/8" max size should work fine. They made no reference to and took no exception to angular vs rounded aggregate, or crushed stone vs naturally occurring material. So, I approved the mix with #89 crushed limestone.

 

[Ron]

Pea gravel, as loosely defined in ACI, has come to mean almost anything simulating smaller coarse aggregate. No. 89 stone is clearly defined and allows a proper concrete mix design with cement content appropriate to the required mix properties as dik noted.

Limerock, the term used in Florida, Georgia,and Alabama for our "less than consistent" (some would say "ratty") limestone, is a viable and good aggregate for concrete when crushed and washed, with aggregate compressive strengths in excess of 10,000 psi.

Specify with clear designations that are not full of ambiguous terms or interpretations.