Davo
44 posts
TimePosted 12/08/2009 08:38:15
Davo says

Alkalies in pozzolans

Dear friends

It is well known, how alkalies from clinker influence on properties of cement and concrete (ASR etc.). Can anyone tell me about cement total alkalies influence, when with clinker are intergrinded pozzolans. Pozzolans are perlytes and amount of alkalies in perlytes is up to 7%. In that case the total amount aof alkalies in cement is about 2%. Has anyone experience with this matter.

Thanks
 

Reply


Know the answer to this question? Join the community and register for a free guest account to post a reply.

srini 1962
6 posts
TimePosted 27/08/2009 09:20:00

Re: Alkalies in pozzolans

If alkalies are of sodium base, then the early strength of the cement martor is expected to increase slightly. But the later  strength will come down.

Reply

Michael Clark
312 posts
TimePosted 27/08/2009 14:24:21

Re: Alkalies in pozzolans

Pozzolana are not necessarily perlytes. The pozzolanic reaction fills the pores in concrete increasing the density and improving the durability.

Reply

Davo
44 posts
TimePosted 27/08/2009 14:45:56
Davo says

Re: Alkalies in pozzolans

Dear Mr Clark

 I know very well what are pozzolans. Pozzolans during hydration of cement react with Ca(OH)2 (with product of reaction of calcium silicates) and form calcium hydro-silicates, so structure of cement paste hardens and durability, hydraulic and sulphur resistant properties of concrete improve.

I asked about influence of such alkalies on properties of cement&concrete (Alkali-Silica Reactions) that enters to cement compositions with pozzolans.

Regards Davit

Reply