Dear Mr. Kunal,

Petrography is one of the most important research methods for the assessment of the technical properties of mortar and concrete.

The instruments for petrographic examination include substantially stereo microscopy, polarized light microscopy (transmitted light and reflected light), dark field microscopy, fluorescence microscopy, electron microprobe, scanning electron microscopy.

Here are a few examples of the examined properties:

1) qualitative and quantitative mineral composition of the rock aggregates

2) grain size of the mineral fragments, size of the rock fragments

3) grain shape of the mineral fragments, the shape of the rock fragments

4) pore volume of the mineral and rock fragments

5) fluid inclusions (liquid, solid, gaseous)

6) the degree of weathering and alteration

7) interaction of mineral and rock components with the binders

8) cracks and fractures in the concrete and / or mortar

9) relationship between crystallization and deformation

In the appendix you will find a publication in which I have examined, together with building engineers petrographic details of concrete, which is affected by damage caused by alkali-silica reactions.

Best regards,

Guenter Grundmann

Dear Mr. Kunal,

Petrography is one of the most important research methods for the assessment of the technical properties of mortar and concrete.

The instruments for petrographic examination include substantially stereo microscopy, polarized light microscopy (transmitted light and reflected light), dark field microscopy, fluorescence microscopy, electron microprobe, scanning electron microscopy.

Here are a few examples of the examined properties:

1) qualitative and quantitative mineral composition of the rock aggregates

2) grain size of the mineral fragments, size of the rock fragments

3) grain shape of the mineral fragments, the shape of the rock fragments

4) pore volume of the mineral and rock fragments

5) fluid inclusions (liquid, solid, gaseous)

6) the degree of weathering and alteration

7) interaction of mineral and rock components with the binders

8) cracks and fractures in the concrete and / or mortar

9) relationship between crystallization and deformation

In the appendix you will find a publication in which I have examined, together with building engineers petrographic details of concrete, which is affected by damage caused by alkali-silica reactions.

Best regards,

Guenter Grundmann

The Book on CONCRETE PETROGRAPHY which contains colopr photomicrograph may useful to your study

Regards

Pravin Bhukte

Dear Mr. Kunal,

Each concrete and mortar is only suitable if the raw materials have certain properties (durability, strength, weathering resistance, etc.).

Only certain raw materials are suitable for this purpose. Even the Romans transported their suitable raw materials from nearby deposits. The quarries and clay pits must be located as close as possible to shorten transport routes.

Today petrographers (mineralogists, geologists) work together with archaeologists, art historians, conservators, curators, engineers, criminologists, etc., to explore and reconstruct the origin, trade routes, history, availability and production technology of concrete and mortar.

Best regards,

Guenter Grundmann

Dear Mr. Kunal,

Please find enclosed the cover of the 'Petrographic Atlas of the Potentially alkali-reactive Rocks in Europe'. This atlas is used in the construction industry as a reference for the quality assurance of concrete. This atlas shows rocks in thin sections, which can cause damage in concrete due to alkali-silica reactions.

Best regards,

Guenter Grundmann

Dear Kunal (Günter),

Petrography is a discipline that provides terminology and jargon for the detailed description ("-graphy") of rocks ("petro-"), enabling objective communication among colleagues. As an assessment technique, petrography is able to reveal spatial distribution of mineral constituents, structure, texture and fabric, hereunder also porosity. By contrast, bulk methods (eg. MIP) provide only bulk data, but no information on whether the porosity volume is homogeneously distributed, or not.

The second edition of the book Concrete Petrography referred to above is scheduled for publication this coming June. The section that is likely to interest you most (Chapter 6: Examination of deteriorated and damaged concrete) has been vastly expanded and extended (more than tripled) compared to the first edition. While the book is not cheap, the investment is worthwhile.

The petrographic atlas referred to directly above is restricted to European rocks only. A brand new atlas comprising rocks from all continents (though I believe off the top of my head, not from India), will be published soon with Springer Verlag. The atlas was prepared for RILEM TC-219 ACS (continued as TC-AAA) as RILEM Guideline AAR-1.2, as a complement to the Petrographic Method (for assessment of concrete aggregate to prevent deleterious AAR) in AAR-1.1. The latter will be published in a separate volume, together with 5 or 6 additional AAR guidelines.

Kind regards,

Maarten Broekmans

Dear Kunal,

One more thing: petrography is principally NOT restricted to size scale, and can be committed macroscopically on hand specimen, as well as microscopically on thin sections (or another type of prepared specimen) using transmitted or reflected light, or using an electron microscope (SEM, TEM, or SEM-EDS/EPMA with analytical capabilities).

Kind regards,

Maarten

Dear Kunal,

The petrograpyic examinations are very wide range of measurements from e.g. grain strength and shape analysis up to AAR providing many useful parameters. In the topic of AAR we have to mention beside the alkali-silica reaction the alkali-carbonate type reaction, too. For instant in Hungary we have good quality quartz gravel but the limestones could be dolomitic and/or containing clay. Directly after the red-mud flood four years ago here in Hungary many samples were collected and examined from the basement of the houses. In that region people commonly used the dolomite or dolomitic limestone in the basement placed together with the 'normal' concrete. These blocks of stone were saturated that time with sodium-hydroxide solution which could be deleterious. In the study the MgO:CaO ratio was studied as function of insoluble residue of dolomitic limestone.

Other purpose of petrographic analysis could be e.g. the role of the stone materials (e.g. crushed aggregate) in the resistivity of concrete to fire or to elevated temperature; or the role of the grain size distribution of gravel in the concrete composition.

In case of your interest in AAR may I suggest you some standard methods, where the importance and the methodology of the petrographic examination is also written and very useful in laboratory examinations: e.g. Standard guide for petrographic examination of aggregate in concrete (ASTM C295), Standard test method for potential reactivity of aggregates (ASTM C289), Richtlinie Alkalireaktion im Beton. In our laboratory the chemical methods usually supported by  thermoanalytical (TG/DTG/DTA) and powder diffraction (XRD) tests. Another important literature: Lamond - Pielert (2006), Significance of test and properties of concrete and concrete-making materials (Ch. 33).

Regarding

Katalin Kopecskó