Seems reasonable, cements contain sulfates, chlorides, and carbonates. The curing process produces heat which may be enough to allow chemical reactions besides the forming of calcium oxy-hydroxides and CO2. Most limestone that would react would be powdered from crushing upon mixing or surface reactions which would allow the cement binder to better hold the aggregate. The anions present would allow for reactions between the normally insoluble in water ingredients of cement in favorable conditions.

Can we say there is no Interfacial Transition Zone (ITZ) around the lime stone aggregate in concrete?

Never can say never, macroscopically, it isn't seen; micro, I haven't noticed, but it could be there.

There is obvious a chemical change but would be insignificant

Can ceramic aggregate used in concrete

Thanks to all of you, limestone is a kind of crystal form of calcium carbonate, which can react with acid, this is why karst landscape is generated in nature. However, since it is an alkaline enverionment in cement(pH~13), therefore the chemical reaction between limestone and cement would be insignificant, same to Khawar`s state. The decomposition of calcium carbonate needs high temperture to above 840°C, which can not happen in cement hydration(the maximum temperature can be 60°C). Another possible reaction is the limestone is saturated with carbon dioxide and water to form bicarbonate, while this carbonation can be prevented by placing soda lime around cement specimens.

I would like to share some points even though not a direct reply regarding your question

Use of Interground Limestone

The limestone addition strategy consists of replacing cement with interground limestone. Since interground limestone is added at the end of the cement production line, the cement-related greenhouse gas (GHG) emissions will be reduced proportionally to the amount of limestone added. The GHG savings arise from avoiding GHG emissions associated with cement production during fuel combustion and calcination in the kiln.maximum GHG savings generated by this strategy is 5 percent, which is the maximum limestone allowance per American Society of Testing Material (ASTM) C 150, a major nationwide cement specification. The effect of limestone addition to cement had not been studied in detail,

pl refer the following for further information

Use of Raw Limestone in Portland Cement (January, 2008) (PDF, 907KB), deals with the three primary indicators of concrete performance: strength, drying shrinkage, and permeability. It was found that limestone improved strength and permeability (at early ages).

Thanks for everybody for enriching the discussion by valued comments. I thing all types of aggregate in concrete should be inert material but the fact there is chemical reaction between cement and aggregate. For limestone dust added to concrete,it isfound that that the dust has a filler effect in additional to accelerate hydration of cement paste.

The limestone filler was considered by many as inert filler, but it has been gradually accepted as contributing to the hydration process by the formation of calicium mono-carboaluminates C3A.CaCO3.11H2O) [Advanced Concrete Technology by John Newman . Ban Seng Choo]

Hi, Naseer,thanks for your comment.

The reaction between limestone filler and cement maybe existes, but as an aggregate, limestone has a much less surface area, this reaction may be eligibilable to contribute to hydration process, I think.

I'm trying to find out your citation from Newman's book [Advanced Concrete Technology], but I couldn't, could you tell me the specific pages related to this topic, thanks a lot.

Can anybody discuss about the carbonate ion portion of limestone powder with reference to alkalinity level of pore solution in concrete?

We always design mixes for lower carbonation rate to avoid corrosion of steel due to reduced alkalinity in carbonated concrete.

Dear Mr. Zhigen Wu.. I can tell you with pleasure

It's in chapter 3 [ Cementitious addition], page 3/58 under article (3.8 Limestone , 3.8.1 limestone filler).

Great thanks to Mr. Naseer Abid On. I've found it.

Thanks TO ALL for the information

Hope you will find a very useful information about the raised question in my publication. 

http://www.sciencedirect.com/science/article/pii/S0950061813007307

I have recently seen instances where lime may be causing a reaction in a concrete slab. The appearance is similar to alkali-aggregate-reaction. The cause may indeed be AAR. I have seen another case where a process plant that uses strong alkaline solution has also concrete slabs with the appearance of AAR. So in both cases I am asking could it be the alkali that is affecting the concrete, and not AAR. Would be very interested to hear of other cases.