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INTRODUCTION
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Petrography sensu stricto is the detailed and systematic description of rocks in handspecimen and in thin-section using high-power microscopy. These same principles can alsobe applied to the various man-made materials used within the construction industry.
Petrography is typically used to identify the mineralogy of natural materials and identify any
potentially deleterious components or features, whilst man-made materials are typicallyexamined to identify the constituents, the overall quality & condition and determine if there isany evidence of deterioration and its causes.
The aim of this brief guide is to illustrate the cornucopia of UKAS-accredited petrographicexamination services that RSK STATS Ltd can provide.
A wide range of complementary expertise within RSK STATS Ltd consultancy practice canaugment any petrographic examination investigation. This includes chemical analysis (mixproportions of mortar, sulfate content of concrete and chloride content of aggregate),physical testing (eg compressive strength of cementitious products and aggregate durabilitytests) and specialist mineralogical and elemental composition/analysis (eg scanning electron
microscopy, X-ray diffraction and X-ray fluorescence).
Before you commence any laboratory investigation programme involving petrography it isadvised that you contact one of our materials scientists.
Address
RSK STATS Ltd
18 Frogmore Road
Hemel Hempstead
HP3 9RTUnited Kingdom
Tel
+44 (0) 1442 437 500
Fax
+44 (0) 1442 437 550
www.stats.co.uk
RSK STATS Ltd
Registered office
Spring Lodge 172 Chester Road Helsby Cheshire WA6 0AR UK
Registered in England No. 2833839
www.rsk.co.uk
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AGGREGATE EXAMINATION
There are four main standard methods that are used to examine aggregates; theymainly vary in level of examination detail and reporting format. They are:-
BS EN 932-3 SimplifiedPetrographic Description of
Aggregate
This method specifies a basic procedure for thebrief petrographic examination of aggregates forthe purposes of general classification. Theprocedure is not suitable for the detailedpetrographical study of aggregates for specific enduses.
For each sample received we produce a factualcertificate estimating the proportions ofconstituents, divided into major, minor and traceconstituents.
Typical turnaround time 10 working days.
BS 812-104: 1994 Petrographic
Examination of Aggregates
This method describes a general method for thedetailed examination of samples of coarse or fineaggregates to determine petrographic compositionand to assist in the assessment of thoseaggregates for potential suitability for the intendeduse (including concrete). There is no ENequivalent to this test.
The major application of the method described is inthe examination and assessment of processedaggregates.
For each sample we produce a detailed certificate,including photomicrographs (photographs takenthrough the microscope), which is supplemented bya factual report that summarises the findings androutinely assesses the alkali-reactivity potential(according to BS 7943 for UK aggregates).
Typical turnaround time 10-15 working days
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AGGREGATE EXAMINATION
Each examination requires a different test portion mass depending on the nominalgrading of the material. Please contact STATS before sending samples to ensure wehave sufficient materials to conduct the examination.
TP83 Petrographic Examination ofAggregates
This method is STATSs in-house procedure that isbased upon BS 812-104. The BS method requiresduplicate test portions to be analysed, whereas our in-house procedure only uses one portion of aggregate.This reduction from two test portions to one means that
we can reduce the turnaround time for the whole high-power microscopical examination whilst still retaining thesame high level of detail.
For each sample we produce a detailed certificate,including photomicrographs (photographs taken throughthe microscope), which is supplemented by a factualcertificate that summarises the findings and routinelyassesses the alkali-reactivity potential (according to BS7943 for UK aggregates).
Typical turnaround time 10-15 working days.
ASTM C295 Petrographic Examinationof Aggregates
This American Standard guide outlines procedures forthe petrographic examination of samples representativeof materials proposed for use as aggregates incementitious mixtures or as raw materials for use inproduction of such aggregates.
This examination goes into similar detail as BS 812-104,but separately analyses different sieve gradings andcalculates the relative proportions of the constituents asa weighted proportion of the overall sample.
For each sample received we produce a factualcertificate detailing and quantifying the individualconstituents.
Typical turnaround time 10-15 working days.
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ROCK EXAMINATION
BS 5930 Petrographic Examinationof Rock
A petrographic description of rock is important notonly for the purposes of geological classificationbut also in order to highlight constituents, texturesand features influencing its chemical, physicaland mechanical behaviour.
It is therefore essential to characterise the rocknot only from the point of view of their mineralcomponents and of their fabric and structure butalso in terms of any features such as: colour,presence of veins, of fossils, of discontinuities,etc.
Typically an examination will include details aboutthe following;
Mineral composition
Structure
Colour/Discoloration
Texture
Grain size
Weathering classification
State of alteration Discontinuities
Fracture state
Geological classification
For each sample we produce a factual certificate,including photographs and photomicrographs(photographs taken using a microscope).
Typical turnaround time 10-15 working days.
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STONE & SLATE EXAMINATION
BS EN 12407 Petrographic Examination of Stone
A petrographic description of natural stone is important not only for the purposes ofpetrographic classification but also in order to highlight constituents, textures and
features influencing its chemical, physical and mechanical behaviour.
A petrographic description will include detail on mineralogy, structure, texture, grain size,state of alteration, discontinuities, fracture state and geological classification.
For each sample we produce a factual certificate, including photographs andphotomicrographs (photographs taken using a microscope).
Typical turnaround time 10-15 working days.
BS EN 12326-2 PetrographicExamination of Slate
The full hand-specimen and low & highmicroscopical examination of slate not onlyhighlights the composition but also determines ifthere are any features that may influence itschemical, physical and mechanical behaviour.
Particular attention is paid to the presence of anyiron sulfide minerals (eg pyrite) that may oxidise inservice and cause deterioration of the slate fabric;any calcite and any residual unaltered clayminerals and geological features that might act asdefects.
The examination can also determine whether theproduct is a true slate (in the geological sense) oranother rock type that may be used a roofing slate(in accordance with BS EN 12326-2).
For each sample we produce a factual certificate,including photographs and photomicrographs(photographs taken using a microscope).
Typical turnaround time 10-15 working days.
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CONCRETE EXAMINATION
ASTM C856 PetrographicExamination of Concrete
Petrographic examination is an essential part of
any laboratory investigation of concrete or anyother cementitious material.
There is no BS or BS EN equivalent of thisstandard. However, ASTM C856 is widelyaccepted as the industry method for theexamination of concrete.
Concrete petrography can be used to investigate abroad scope of features, including constituents,quality and condition:-
Constituents
Aggregate type
Aggregateconstituents
Aggregatecontaminants
Matrix characteristics
Mineral additives
Cement type
Quality & Condition
Air void content
Water/cement ratio
Compaction
Microporosity
Carbonation (degree& depth)
Portlandite
Investigations into possible distress and/ordeterioration, including:
Fire-damage
Delayed ettringite formation (DEF)
Sulfate attack
Internal sulfate attack
Thaumasite form of sulfate attack (TSA)
Secondary deposits & leaching
Alkali-aggregate reaction (AAR)
Chemical attack
Aggregate shrinkage
Freezing and freeze-thaw cycling
For each sample we produce a factual certificate,including core log, photographs andphotomicrographs (photographs taken using amicroscope).
Typical turnaround time 10-15 working days.
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MATERIALS EXAMINATION
Petrographic Examination of Materials
Photomicrographs (photographs taken through an optical microscope) are shownbelow illustrating some of the other materials that are examined using the sametechniques:-
Sand/cementmortar
Screed
Lime mortar Paint
Render Plaster
Adhesivecompounds
Levellingcompounds
Bricks & tiles Fibre-cementproducts
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A c o u s t i c sS a m p l i n g
EcologyA i r q u al i t y Te l em et r y
Des k s t u d i es Mo n i t o r i n g
Si t e ap p r a i s a l In v es t i g a t i o n
Ri s k as s es s m en t In s i t u t es t i n g
Th em at i c m ap p i n g In s t r u m en t a t i o n
Co m p u t er m o d el l i n g Co r i n g an d d r i l l i n g
En v i r o n m en t a l au d i t i n g F l o o d r i s k as s es s m en t
Geo p h y s i c al Su r v ey i n g Co n f i n ed s p ac e an d r o p ed ac c es s
En v i r o n m en t al i m p ac t as s es s m en t En g i n eer i n g & en v i r o n m en t al d es i g n
Pr o d u c t an d c o m p o n en t t es t i n g On -s i t e l ab o r a t o r y t es t i n g
Dat ab as e & i n t er n et s er v i c es En v i r o n m en t a l s i m u l at i o n
En v i r o n m en t al m an ag em en t Pet r o g r ap h i c ex am i n a t i o nD a m p n e s s s u r v e y i n g N o n - d e s t r u c t i v e t e s t i n g
Co n t r ac t ad m i n i s t r a t i o n Co n s u l t an c y & ad v i c e
En g i n eer i n g an a l y s i s QA /QC In s p ec t i o n
Pr o j ec t m an ag em en t Laboratory testing
Val u e en g i n eer i n g Ch em i c a l an a l y s i s
P r o b l em s o l v i n gT r a i n i n g
E x p e r t w i t n e s s k
RSK STATS Ltd
18 Frogmore Road, Hemel Hempstead
Hertfordshire HP3 9RT
Tel: 01442 437500, Fax: 01442 437 550
Email: [email protected]: www.stats.co.uk
RSK STATS Geoconsult Ltd - Coventry Office
The Enterprise Centre,
Puma Way, CoventryCV1 2TX
Tel: 02476 236816, Fax: 02476 236014
Ground & Environment
Asbestos & WaterManagement
Materials & Structures
0278 251
RSK STATS Ltd 2009
RSK STATS Ltd (formerly STATS Limited, founded 1974) is a specialist firm of engineering and materials
consultants. The group encompasses a wide range of professional engineers, scientists and technologists, with
extensive experience in litigation, arbitration and other forms of dispute resolution on a wide range of civil,
structural, and geotechnical engineering topics, building technology, building and construction materials and
environmental issues.
