Silica or Carbonate Sand?

[charnott]

Our QA/QC department (we are the PMC) have questions over the sand being used by the contractor as replacement sand in the sand replacement test as outlined by BS1377-9 Sect 2.1

The BS requires the replacement sand be clean, closely graded silica sand, provides a consistent bulk density and within a certain PSD corridor. I can test the material for all of the above without any issue, my question pertains to proving that the material is silica sand.

In my personal opinion the material is clearly a silica sand being quartz derived and is certainly not a carbonate sand however i am required by the QA/QC dept to prove that.

Is there a standard classification test to decide the composition? Could i do a carbonate content test, but where could i find a definition of what carbonate content values clearly demonstrate it is a silica sand, zero?

Assistance greatly appreciated as ever.

Chris

 

[Ron]

Drop a bit of hydrochloric acid (muriatic acid) or acetic acid (vinegar) on the sand. If it fizzes, it is carbonate or at the least, calcareous. If no fizzing, not carbonate and likely silica.

 

[charnott]

Ron - that approach had crossed my mind however QA/QC are unlikely to accept an approach without some sort of testing standard/reference attached to it......ahhh the joys of being on a mega-project, everyone's an expert!

 

[Ron]

charnott....I see that you are working to British Standards. Can't help you there. It is a common test in the US for many state departments of transportion. If you can use a reference other than a British Standard, I'll see what I can do.

 

[Ron]

charnott...another thought...

This is a basic chemical reaction that doesn't require a procedure or standard for a qualitative test. If you wanted quantification, then a standard would be appropriate.

Perhaps you can argue that with QA/QC

 

[charnott]

Ron - thanks again for the input. I am definitely going to go down the route of an acid test and see what reaction i get (from QA/QC not the sand!). Its a no-brainer for me as i am 100% certain the material is dune sand and therefore must be silica.

However should common sense fail to prevail i would be interested in any ASTM or AASHTO etc standards i might be able to call upon??

Cheers