Effect of Coarse Aggregate Size and Roughness on Concrete Strength?

[zlindauer]

I am working on a project where the the contractor is concerned about honeycombing in a particular pour. The contractor has requested that the size of the coarse aggregate be reduced from 1" to 3/8" for this pour. He has also requested that river rock be used instead of crushed limestone, which would mean a smoother stone would be used. I suppose it would be difficult to get 3/8" crushed limestone.

Does anyone have any information on the effect of coarse aggregate size and roughness on the quality and strength of concrete?

Thanks.

 

[ATSE]

See thread 507-315298 for a similar discussion.

 

[concretemasonry]

I imagine there was a specification regarding the concrete performance and there were mix designs and test results approved in advance.

A change from 1" to 3/8" suggests that there are limited local aggregate options.

If there was the proper design and specification, just enforce the specs and requirements or pay the extra cost of materials required for the adjusted allowable materials. - Freight/shipping on aggregate can be costly in many areas and could raise concrete material costs by 50% based on freight and added cement for angular aggregates and difference in placement.

It could be that the mix approved may not have be proper for the application (harshness, rebar spacing, concrete cover). More information would be helpful.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.