Concrete Aggregates: Crushed vs Natural(Rounded)

[AKSherpa]

I am interested in others experiences, thoughts, knowledge, ect. concerning concrete aggregates, specifically crushed vs. non-crushed. When I lived in midwest US it was comon to use crushed products in concrete. I am now in Alaska where it is much more common to use alluvial aggregates for concrete. Occasionally in Alaska I have come across situations where people have the opinion that crushed aggregates can't be used for concrete. This situation has occured where a very large difference in cost could be incurred for importing natural aggregates vs. using locally crushed aggregates.

Any comments on this issue appreciated.

Thanks

 

[flight7]

I may be mistaken, but I have heard that crushed aggregate tends to have higher strength due to the non-smooth shape. (I haven't searched for any sources on this to confirm my memory.) Regardless, if the supplier's cylinder test history shows sufficient strength for the aggregate they are using, whatever the shape, you should be fine. And if you're remote and mixing on site with local material then you probably want to do some testing anyway.

 

[LittleWheels]

You tend to need a little more cement paste to cover the angular aggregate's increased surface area but otherwise no major problems, provided the angular aggregate is fairly regular in shape, rather than flaky. I don't know the situation in your region but crushed aggregate shape could be an issue.

 

[AKSherpa]

Thanks for the replies. I am surprised I did not get more response from this post. Many times in AK I have heard it stated that crushed agregates would not work for concrete, seemed like ability to finish was one of the concerns. I always find it odd, in Missouri we use crushed coarse aggregates for concrete.

 

[dauwerda]

I am surprised I did not get more response from this post.

You would probably get more traction in the general structural engineering forum - A lot more people frequent that one. You could put a post there with a link to this one or delete this one and start a new post.

I have always been under the impression that crushed aggregate was superior to rounded aggregate but I guess I'm not sure if I know that to be true. I usually only see requests to use pea gravel or rounded river rock when they are trying to make it more pump friendly.

I too would be curious to know if there is a major difference between the two options when it comes to performance of the concrete and what those might be.

 

[BulbTheBuilder]

I like literature when it comes to these topics.

I haven't read this article, but I will read it today. I am curious myself.
Experimental study and comparison between the use of natural and artificial coarse aggregate in concrete mixture

Effects of aggregate type, size, and content on concrete strength and fracture energy

 

[dik]

Slightly higher due to the aggregate interlock effect.

 

[System Protection]

This is way outside my wheelhouse, but it did remind me of a recent video by Practical Engineering on Youtube.

Some interesting comment as well on the video.